ARTICLE | doi:10.20944/preprints202309.1317.v2
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Ostwald; chains; cyanopolyynes; carbon nitride; half dome
Online: 25 September 2023 (04:55:57 CEST)
We report on a new form of nanoscale carbon nitride in the shape of single layer half dome structures grown on the step edges of boron nitride sheets. The half dome structure grown on the step edges of boron nitride sheets. The half dome structures are formed spontaneously at high temperature using Iron oxide nanoparticles capped with tetremethylammonium hydroxide supported on BN sheets. During the combustion process the support, firstly, acted as a reducing agent, secondly, as a source of nitrogen that permitted the transformation of the organic capping agent in sp1 CN chains linked with sp2 CN domains. During the Ostwald ripening process smaller nanoparticles migrates towards bigger nanoparticles, when the nanoparticles come across the step edges of few layer boron nitride sheets the half dome structure is formed. This new method of synthesis has demonstrated for the first time the formation of half dome structures containing cyanopolyynes sp1 chains and sp2 carbon nitride domains.
ARTICLE | doi:10.20944/preprints202309.0350.v3
Subject: Chemistry And Materials Science, Nanotechnology Keywords: zirconium dioxide; stability; yttrium-stablized ZrO2 (YSZ); oxygen vacancy; enthalpy and entropy; doped-induced phase transition; fermi level shift
Online: 21 September 2023 (09:56:20 CEST)
In this study, we considered the structural stability, electronic properties, and phonon dispersion of the cubic (c-ZrO2), tetragonal (t-ZrO2), and monoclinic (m-ZrO2) phases of ZrO2. We found that the monoclinic phase of zirconium dioxide is the most stable among the three phases in terms of total energy, lowest enthalpy, highest entropy, and other thermodynamic properties. The smallest negative modes were found for m-ZrO2. Our analysis of the electronic properties showed that during the m–t phase transformation of ZrO2, the Fermi level first shifts by 0.125 eV toward higher energies and then decreases by 0.08 eV in the t–c cross-section. The band gaps for c-ZrO2, t-ZrO2, and m-ZrO2 are 5.140 eV, 5.898 eV, and 5.288 eV, respectively. Calculations based on the analysis of the influence of doping 3.23, 6.67, 10.35, and 16.15 mol. %Y2O3 onto the m-ZrO2 structure showed that the enthalpy of m-YSZ decreases linearly, which accompanies further stabilization of monoclinic ZrO2 and an increase in its defectiveness. A doping-induced and concentration-dependent phase transition in ZrO2 under the influence of Y2O3 was discovered, due to which the position of the Fermi level changes and the energy gap decreases. It has been established that, not only for pure systems but including those doped with Y2O3, the main contribution to the formation of the conduction band is made by the p-states of electrons. The t-ZrO2 (101) and t-YSZ (101) surface models were selected as optimal surfaces for water adsorption based on a comparison of their surface energies. An analysis of the mechanism of water adsorption on the surface of t-ZrO2 (101) and t-YSZ (101) showed that H2O on unstabilized t-ZrO2 (101) is adsorbed dissociatively with an energy of -1.22 eV, as well as by the method of molecular chemisorption with an energy of - 0.69 eV and the formation of a hydrogen bond with a bond length of 1.01 Å. In the case of t-YSZ (101), water is molecularly adsorbed onto the surface with an energy of -1.84 eV. Dissociative adsorption of water occurs at an energy of -1.23 eV, near the yttrium atom. The results show that ab initio approaches are able to describe the mechanism of doping-induced phase transitions in (ZrO2+Y2O3)-like systems, based on which it can be assumed that DFT calculations can also flawlessly evaluate other physical and chemical properties of YSZ, which have not yet been studied quantum chemical research. The obtained results complement the database of research works carried out in the field of the application of biocompatible zirconium dioxide crystals and ceramics in green energy generation and can be used in designing humidity-to-electricity converters and creating solid oxide fuel cells based on ZrO2.
ARTICLE | doi:10.20944/preprints202309.1429.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: optical properties; degree of imidization; polyimide nanocomposite films; polyaniline copolymer/clay nanocomposites; Atomic Force Microscopy; dynamic mechanical analysis
Online: 21 September 2023 (08:27:06 CEST)
Neat polyimide films are known to be dense and rigid. They are therefore not suitable for use in membranes, sensors and sustainable energy storage applications. In this study a novel technique has been used to simulta-neously improve the rigidity, damping ability and impact resistance of polyimide membranes. It is demonstrated that dispersion of a small amount of polyaniline copolymer-modified clay of about 0.25-0.5 wt.% into the pol-yimide matrix, resulted in enhanced storage modulus while maintaining high damping ability and glass transition temperature, Tg. Novel polyimide/substituted polyaniline-copolymer-clay nanocomposite membranes containing poly(N-ethyl-aniline-co-aniline-2-sulfonic-acid-modified-clay (SPNEAC) was successfully prepared and in-corporated into polyimide matrix to form modified clay/polyimide nanocomposites. UV-Vis analysis of the nanocomposite films show that the optical transparency of the SPNEAC-PI nanocomposite membranes de-creased with increasing SPNEAC concentration due to the high UV-Vis absorption of SPNEAC. Transmittance of about 3 % was observed in the nanocomposite membrane containing 5wt.% modified clay at 500 nm wave-length, which is significantly lower than that for the neat PI membrane of about 36 %. The dispersion of SPNEAC containing high concentration of clay (≥ 40 wt.% clay), SPNEAC2 in polyimide matrix, resulted in attainment of a higher degree of imidization than was possible for the neat organoclay/polyimide nanocomposite. This behavior is believed to be due to the synergistic interaction between PI and polyaniline copolymer modified clay. The viscoelastic property of polyimide and the nanocomposite membranes was measured by using the dynamic mechanical spectroscopy, DMS. It was shown that the glass transition temperature, Tg of the nano-composites decreased, while the damping ability and impact energy increased with increasing weight fraction of fillers.
ARTICLE | doi:10.20944/preprints202309.0810.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: bicontinuous composites; carbonized leather waste; conducting polymer; globular polypyrrole; polypyrrole nanotubes; conductivity; resistivity; dye adsorption; Raman spectra
Online: 13 September 2023 (16:17:08 CEST)
Leather waste was carbonized at 800 °C in inert atmosphere. The resulting biochar was coated in situ with polypyrrole nanotubes produced by the oxidation of pyrrole in the presence of methyl orange. The composites of carbonized leather with deposited polypyrrole nanotubes of various composition were compared with similar composites based on globular polypyrrole. Their molecular structure was characterized by infrared and Raman spectra. Both conducting components formed a bicontinuous structure. The resistivity determined by four-point van der Pauw method was monitored as a function of pressure applied up to 10 MPa. The typical conductivity of composites was of the order of tenths to units S cm−1 and it was always higher for polypyrrole nanotubes than for globular polypyrrole. The conductivity decreased by 1–2 orders of magnitude after treatment with ammonia but still maintained a level acceptable for applications operating under non-acidic conditions. The composites were tested for dye adsorption, viz. cationic methylene blue and anionic methyl orange, using UV-spectroscopy. The composites are designed for the future use as functional adsorbents controlled by the electrical potential.
ARTICLE | doi:10.20944/preprints202308.0586.v3
Subject: Chemistry And Materials Science, Nanotechnology Keywords: zirconium dioxide; stability; yttrium-stabilized ZrO2 (YSZ); oxygen vacancy; enthalpy and entropy; doped-induced phase transition; fermi level shift
Online: 12 September 2023 (16:58:32 CEST)
In this study, we considered the structural stability, electronic properties, and phonon dispersion of the cubic (c-ZrO2), tetragonal (t-ZrO2), and monoclinic (m-ZrO2) phases of ZrO2. We found that the monoclinic phase of zirconium dioxide is the most stable among the three phases in terms of total energy, lowest enthalpy, highest entropy, and other thermodynamic properties. The smallest negative modes were found for m-ZrO2. Our analysis of the electronic properties showed that during the m–t phase transformation of ZrO2, the Fermi level first shifts by 0.125 eV toward higher energies and then decreases by 0.08 eV in the t–c cross-section. The band gaps for c-ZrO2, t-ZrO2, and m-ZrO2 are 5.140 eV, 5.898 eV, and 5.288 eV, respectively. Calculations based on the analysis of the influence of doping 3.23, 6.67, 10.35, and 16.15 mol. %Y2O3 onto the m-ZrO2 structure showed that the enthalpy of m-YSZ decreases linearly, which accompanies further stabilization of monoclinic ZrO2 and an increase in its defectiveness. In this case, the position of the Fermi level changes abruptly, and the energy gap decreases. It has been established that, not only for pure systems but including those doped with Y2O3, the main contribution to the formation of the conduction band is made by the p-states of electrons. The t-ZrO2 (101) and t-YSZ (101) surface models were selected as optimal surfaces for water adsorption based on a comparison of their surface energies. An analysis of the mechanism of water adsorption on the surface of t-ZrO2 (101) and t-YSZ (101) showed that H2O on unstabilized t-ZrO2 (101) is adsorbed dissociatively with an energy of -1.22 eV, as well as by the method of molecular chemisorption with an energy of - 0.69 eV and the formation of a hydrogen bond with a bond length of 1.01 Å. In the case of t-YSZ (101), water is molecularly adsorbed onto the surface with an energy of -1.84 eV. Dissociative adsorption of water occurs at an energy of -1.23 eV, near the yttrium atom. The obtained results complement the database of research works carried out in the field of the application of biocompatible zirconium dioxide crystals and ceramics in green energy generation and can be used in designing humidity-to-electricity converters and creating solid oxide fuel cells based on ZrO2.
ARTICLE | doi:10.20944/preprints202309.0623.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: nanophosphors; Zn2GeO4; hydrothermal synthesis; luminescence
Online: 11 September 2023 (07:55:08 CEST)
Zn2GeO4 is considered a very promising alternative to current luminescent semiconductors. Previous results suggest that its emitted wavelength may depend on different variables, such as particle size and morphology, among others. In this work, we have prepared pure and highly homogeneous Zn2GeO4 nanorods under hydrothermal synthesis conditions with a willemite-like structure. Their luminescent properties have been explored and their band gap estimated, which are distinct to previously reported Zn2GeO4 bulk particles. Therefore, our results identify particle morphology as a crucial factor for maximizing and fine-tuning the luminesce of Zn2GeO4 nano-phosphors.
ARTICLE | doi:10.20944/preprints202309.0423.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Mineral filled composites; Nano composite; Organo clay; Melamine formaldehyde, Thermal insulation, Mechanical strength, Hybrid composites
Online: 7 September 2023 (03:25:39 CEST)
Generally, mineral fillers are added to thermoplastic polymers to reduce cost and improve performance. However, properly selected mineral fillers can also improve thermal conductivity and deformation behavior, shrinkage, impact strength, dimensional stability, and molding cycle time in thermoset polymers. This study focused on the preparation and microscopic and spectroscopic characterization of various hybrid composites using pumice as primary filler and gypsum, kaolin and hollow glass sphere as secondary fillers, as well as examining some of their mechanical properties and thermal conductivities. For this, first of all, surface modification of the clay was carried out by intercalation method from solution using raw Montmorillonite, cationic surfactant and long chain hydrocarbon material, and then organo-clay melamine formaldehyde nanocomposite was prepared by in situ synthesis using organo clay and melamine formaldehyde pre-polymer. Finally, non-ionic surfactant, foaming agent and glycerin were added to the prepared nano-composite at approximately 90°C, mixed mechanically and then pumice was added. The processes at this stage were repeated while preparing hybrid composites with pumice and other mineral additives. For curing and molding, the composite was first subjected to microwave irradiation for 5 minutes followed by thermal treatment at 140°C for 60 min. Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD) spectra and Scanning electron microscope (SEM) and High resolution transmission electron microscope (HRTEM) images were taken for morphological and textural characterization for raw clay (MMT), organo clay (OMMT) and pure polymer with prepared hybrid composites. In addition, some mechanical properties such as bending strength, elasticity modulus and screw holding resistance, as well as thermal conductivity coefficients of the hybrid composites were determined according to the relevant standards and the obtained results were evaluated. Spectroscopic and microscopic analyzes have shown that effective adhesion interactions occur between polymer-clay nanocomposite particles and filler grains, thus resulting in textural arrangements with different properties. Mechanical and thermal conductivity test results showed that melamine formaldehyde-organo-clay nano composite foam and hybrid composite containing hollow glass sphere are highly qualified materials in terms of thermal insulation and mechanical strength.
ARTICLE | doi:10.20944/preprints202308.2130.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Magnetic nanoparticles; chitosan; XRD; FESEM; FTIR; DLS; VSM; Applications
Online: 31 August 2023 (09:45:41 CEST)
The suspension cross-linking technique has been utilized to create the magnetic chitosan nanoparticles, which were then applied to the magnetic carrier method at 80°C. First the FeCl2 and FeCl3 solution co-precipitated and synthesized Fe3O4 for utilization in the formation of magnetic chitosan nanoparticles, it has been characterized by utilizing DLS (Dynamic light scattering), XRD (X-ray diffraction spectrometer), FTIR (Fourier transform infrared spectroscopy), which identified structure, size, FE-SEM (Field Emission Scanning Electron Microscope) and HR-TEM (High-resolution transmission electron microscopy) which identified structure and particle size whereas magnetic behavior of chitosan nanoparticles was determined by VSM (Vibrating sample magnetometer). According to the results collected, the magnetic chitosan nanoparticles have been spherical in form and size ranging from around 250 to 400 nm.
ARTICLE | doi:10.20944/preprints202308.2061.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: hydrogenation; palladium-silver catalysts; polysaccharide; 2-hexyn-1-ol
Online: 30 August 2023 (08:43:32 CEST)
A new one-pot technique for preparation of polysaccharide-based Pd- and Pd-Ag nanocatalysts by sequential supporting natural polymer (2-hydroxyethyl cellulose (HEC), chitosan (Chit), pectin (Pec)) and metals on zinc oxide was developed. The nanocatalysts based on polysaccharide were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller (BET), infrared spectroscopy (IRS), X-ray powder diffraction (XRD), X-ray photoelectron spectra (XPS) and elemental analysis methods. The catalyst characterization results indicated complete adsorption of polysaccharide and metal ions on zinc oxide, forming polymer-stabilized Pd nanoparticles of ~2 nm in size, evenly distributed on the support surface. The catalysts were studied in the hydrogenation of 2-hexyn-1-ol under mild conditions (0.1 MPa, 40 °C). The catalysts demonstrated nearly the same conversion of 2-hexyn-1-ol. The selectivity to cis-hexen-1-ol of the catalysts decreases in the following order: 0.5%Pd-Ag(3:1)HEC/ZnO>0.5%Pd-Ag(3:1)Pec/ZnO>0.5%Pd-Ag(3:1)Chit/ZnO. The optimum reaction temperature and catalyst loading for the Pd-Ag catalysts modified with HEC and Chit have been determined (40 °C, 0.05 g).
REVIEW | doi:10.20944/preprints202308.1927.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: nanoparticles; graphene; graphene oxide; cytotoxicity
Online: 29 August 2023 (09:15:58 CEST)
Graphene-based nanoparticles possess remarkable physiochemical properties, making them promising for diverse applications in biomedicine, agriculture, food, and industrial applications. These nanoparticles have also been used in the fight against COVID-19. Human and environmental exposure to graphene-based nanomaterials is increasing at an unprecedented rate. However, there is still a huge knowledge gap regarding its safety in clinical applications. The topic remains controversial; although several routes of degradation exist, the cytotoxicity of graphene-based nanoparticles has been demonstrated. Various factors that can influence the cytotoxicity of graphene-based materials are discussed. This review summarizes the physiochemical properties of graphene-based materials and critically examines the possible effects of graphene-based nanoparticles on the molecular level and adverse health outcomes. While oxidative stress-mediated cell damage has been proposed as a primary cytotoxicity mechanism for graphene-based materials, various in vivo biodistribution and cytotoxicity mechanisms are also highlighted. Therefore, this review of the literature provides an overview of the cytotoxicity of GBMs and raises concerns about their widespread application with potential hazardous consequences on the environment and human health.
ARTICLE | doi:10.20944/preprints202308.1635.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Biofilm; silver; bone; nanotechnology; impregnation; bacteria; NDM; scaffold
Online: 23 August 2023 (07:19:07 CEST)
Background: Antibiofilm activity of silver nanoparticles has been extensively investigated in common bacteria. Metallo-β-lactamase producing Gram-negative bacteria are hard-to-treat microorganisms with few therapeutic options, and silver nanoparticles were not evaluated on the biofilm of these bacteria. Objectives: The aim of this study was to evaluate the antibiofilm activity of a bone scaffold impregnated with silver nanoparticles in NDM-producing Gram-negative bacilli. Methods: Bone scaffolds from bovine femur were used for the tests and impregnated with silver nanoparticles (50 nm) by physical adsorption. Silver nitrate minimal inhibitory and bactericidal concentrations (MIC and MBC) were performed on NDM-producing Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa. Disc diffusion tests for silver nanoparticles susceptibility and quantification of biofilm production on plate and bone with sessile cell count were performed. Results: The MIC results demonstrated that silver nitrate had an antimicrobial effect on all microorganisms, inactivating the growth of isolates from a concentration of 8 µg/mL. MBC results showed that E. coli 16.211 was the only isolate to present MIC different from MBC, with a value of 16 µg/mL. Conclusion: Bone scaffolds impregnated with silver nanoparticles can significantly reduce biofilm, and it can be a strategic material to be used as an implant for different approaches.
ARTICLE | doi:10.20944/preprints202308.1488.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: gold nanoparticles; lens; coating; characterisation
Online: 22 August 2023 (10:54:21 CEST)
The surface plasmon resonance of gold nanoparticles causes visible light absorption and scattering effects that may be used in optical coatings for eliminating blue light emission from display monitors, blocking UV light and for decorative applications. This study examines the achievement of functional properties provided by gold nanoparticles in a commercially established C60 fullerene-coated eyewear product. The gold nanoparticles used were sourced from recycling rapid lateral flow tests (LFIA), which use gold nanoparticles as test markers. After the gold`s recovery Ultrasonic Spray Pyrolysis (USP) with freeze-drying was used for the synthesis of new gold nanoparticles, to be used in optical coatings. The gold nanoparticles were examined with SEM, TEM, DLS, zeta potential, BET, and Vis-NIR for characterising their shapes and sizes, required for determination of the surface plasmon resonance effect. After applying the newly produced gold nanoparticles with fullerene C60 in a combined coating for eyewear lenses, the absorption and transmission of the lenses was determined for establishing changes in the coating functionality. The results show that enhancing the fullerene C60 coating with gold nanoparticles improves light absorption and reflectance for blue and UV light further, which may be evaluated as beneficial for the eyewear user, as the reduction of eye strain is improved due to the coating.
ARTICLE | doi:10.20944/preprints202308.1387.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: bio-graphen; metal-free; doped; antibiotic
Online: 22 August 2023 (07:35:03 CEST)
Wastewater contaminated with antibiotics is a major environmental challenge. We developed here the green synthesis of bio-graphenes by using natural precursors (Xanthan, Chitosan, Boswellia, Tragacanth). The use of these precursors can act as templates to create 3D doped graphene structures with special morphology. Also, this method is a simple method for in-situ synthesis of doped graphenes. The elements present in the natural polymers (N) and other elements in the natural composition (P, S) are easily placed in the graphene structure and improve the catalytic activity due to the structural defects, surface charges, increased electron transfers, and the high absorption. In this mechanism, O2 dissolved in water absorbs onto the positive charged C in doped graphenes to create oxygenated radicals, which enables the degradation of antibiotic molecules. Light irradiation increases the amounts of radicals and rate of antibiotic removal. The results have shown that the hollow cubic Chitosan-derived graphene has shown the best performance due to the doping of N, S, and P. The Boswellia-derived grapheme shows the highest surface area, but lower catalytic performance, which indicates the more effective role of doping in the catalytic activity. The effect of oxygen and light were also studied to accelerate the degradation process.
ARTICLE | doi:10.20944/preprints202308.1430.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: goethite nanoparticles; impedance spectroscopy; Fourier Transform Infrared Spectros-copy (FT-IR); visible-light activated photocatalyst; cathode active material; sodium-ion batteries; lithium-ion batteries
Online: 21 August 2023 (07:21:12 CEST)
The present study investigates the relationship between the local structure, photocatalytic ability, and cathode performances in sodium-ion batteries (SIBs) and lithium-ion batteries (LIBs) using Ni-substituted goethite nanoparticles (NixFe1-xOOH NPs) with a range of 'x' values from 0 to 0.5. The structural characterization was performed applying various techniques, including X-ray diffractometry (XRD), Thermogravimetry differential thermal analysis (TG-DTA), Fourier Transform Infrared Spectroscopy (FT-IR), X-ray absorption spectroscopy (XANES/EXAFS), both measured at room temperature (RT), and 57Fe Mössbauer spectroscopy recorded at RT and at low temperatures (LT) from 20 K to 300 K, Brunauer-Emmett-Teller surface area measurement (BET), and diffuse reflectance spectroscopy (DRS). In addition, the electrical properties of NixFe1-xOOH NPs were evaluated by impedance spectroscopy. XRD showed the presence of goethite as the only crystalline phase in prepared samples with x ≤ 0.20, and goethite and α-Ni(OH)2 in the samples with x > 0.20. Sample with x = 0.10 (Ni10) showed the highest photo-Fenton ability with a first-order rate constant value (k) of 15.8×10-3 min-1. The 57Fe Mössbauer spectrum of Ni0, measured at RT, displayed a sextet corresponding to goethite, with an isomer shift (δ) of 0.36 mm s-1 and a hyperfine magnetic distribution (Bhf) of 32.95 T. Moreover, the DC conductivity decreased from 5.52×10-10 to 5.30×10-12 (Ω.cm)–1 with 'x' increasing from 0.10 to 0.50. Ni20 showed the highest initial discharge capacity of 223 mAh g-1, attributed to its largest specific surface area of 174.0 m2 g-1. In conclusion, NixFe1-xOOH NPs can be effectively utilized as visible-light-activated catalysts and active cathode materials in secondary batteries.
ARTICLE | doi:10.20944/preprints202308.1256.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Titania; nanoparticles; aggregates; morphologies; Li-ion batteries
Online: 17 August 2023 (13:11:45 CEST)
Anode materials based on TiO2 nanoparticles of different morphologies were prepared using the hydrothermal method and characterized by various techniques, such as X-ray diffraction (DRX), scanning electron microscopy (FE-SEM), and N2 absorption. The TiO2 nanoparticles prepared were used as anode materials for lithium-ion batteries (LIBs), and their electrochemical properties were tested using discharging/charging measurements. The results showed that the initial morphology of the nanoparticles plays a minor role in battery performance after the first few cycles and that better capacity was achieved for TiO2 nanobelt morphology. The sharp drop in the specific capacity of LIB during their first cycles is examined considering changes in the morphology of TiO2 particles and their porosity properties in terms of shape and connectivity.
REVIEW | doi:10.20944/preprints202308.1090.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Nanomedicine; implantable; wearable devices
Online: 15 August 2023 (05:19:50 CEST)
In this communication the concept of functional materials is understood such as real modified substrates for nanomedicine applications. Functional and modified substrates focused on microcapsules and devices for new nanomedicine diagnosis and treatments. Cases of different materials are shown to support the functionality strategy, as in particular chemicals, pharmacophores, and controlled nano-chemistry for the design of nanoplatforms. Recent studies have reported hybrid inorganic/organic compositions for biocompatible, biodegradable, and support materials added to particular physical properties such as conductive, semiconductive, and high electromagnetic fields from the near field within the nanoscale to far-field applications and new nano-pharmacophores and nanomedicine therapeutics. New approaches are shown from the nano-scale to the micro- and higher sizes of substrates for improved therapeutic strategies. Micro-capsules for biosensing and drug delivery applications were developed. In addition, we report recent and novel research centered on implantable, portable, and wearable devices applied to future treatments.
ARTICLE | doi:10.20944/preprints202308.0977.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Heterojunction; photocatalytic H2 production; carbon nitride; nanosheets; ZnCdS
Online: 14 August 2023 (04:32:05 CEST)
Herein, we have fabricated graphitic carbon nitride (g-C3N4) nanosheets with embedded ZnCdS nanoparticles to form a type II heterojunction using a facile synthesis approach and used for photocatalytic H2 production. The morphologies, chemical structure and optical properties of the obtained g-C3N4‒ZnCdS samples were characterized by a battery of techniques such as, TEM, XRD, XPS and UV-Vis DRS. The as-synthesized g-C3N4‒ZnCdS, photocatalyst exhibits the highest hydrogen production rate of 108.9 μmol·g-1·h-1 compared to individual components (g-C3N4: 13.5 μmol·g-1·h-1, ZnCdS: 45.3 μmol·g-1·h-1). The improvement of its photocatalytic activity is mainly attributed to the heterojunction formation and resulting synergistic effect, which provide more channels for charge carrier migration and reduce the recombination of photogenerated electrons and holes. Meanwhile, the g-C3N4‒ZnCdS heterojunction catalyst also showed higher stability over a number of repeated cycles. Our work sheds insight of using g-C3N4 and metal sulfide combination to develop low-cost, efficient, visible-light active hydrogen production photocatalysts.
ARTICLE | doi:10.20944/preprints202308.0694.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: quantum cascade laser; molecular beam epitaxy; InAlAs/InGaAs
Online: 8 August 2023 (17:07:25 CEST)
In this paper we present methodology for precise calibration of Molecular Beam Epitaxy (MBE) growth process and achieving run to run stability of growth parameters. We present the analysis of the influence of fluxes stability during the growth of long wavelength quantum cascade laser structures designed for the range λ ~ 12–16 µm on wavelength accuracy with respect to desired emission wavelength. The active region of the lasers has a complex structure of nanometer thickness InxGa1-xAs/InyAl1-yAs superlattice. As a consequence, the compositional and thickness control of the structure via bulk growth parameters is rather difficult. To deal with this problem we employ methodology based on double-superlattice test structures, that precede the growth of the actual structures. The test structures are analyzed by high-resolution X-ray diffraction which allows to calibrate the growth of the complex active region of quantum cascade laser structures. We also study theoretically the effect of individual flux changes on emission wavelength and gain parameters of the laser. The results of simulations allow for determination of flux stability tolerance, preserving acceptable parameters of the laser and provide means of emission wavelength control. The proposed methodology was verified by the growth of laser structures for emission at around 13.5 μm.
ARTICLE | doi:10.20944/preprints202308.0133.v2
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Silver nanoparticles; Green synthesis; full factorial design synthesis
Online: 8 August 2023 (12:53:36 CEST)
Silver nanoparticles from Origanum vulgare (Oregano) have been synthesized in the past. However, no investigation has been performed on the combined effects of independent factors that affect the synthesis. Silver nitrate and Oregano concentrations, incubation temperature and time, as well as pH can play crucial roles in synthesis. In this regard Full Factorial Design was applied. A Voigt function was fitted on the measured UV – Vis spectra. The fitting parameters of the Voigt function (peak wavelength, area, and Full Width at Half Maximum) were used as the responses. A quadratic model was fitted for the peak wavelength and area, and the pH proved the dominant factor on nanoparticle synthesis.
ARTICLE | doi:10.20944/preprints202308.0508.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Carbon Nanotube Paper; bucky paper; diode; microwave; filter
Online: 7 August 2023 (10:16:17 CEST)
This study aims to exploit the distinctive properties of carbon nanotube materials, which are particularly pronounced at the microscopic scale, by deploying fabrication techniques that allow their features to be observed macroscopically. Specifically, we aim to create a semiconductor device that exhibits flexibility and the ability to modulate its electromagnetic wave absorption frequency by means of biasing. Initially, we fabricate a sheet of carbon nanotubes through a vacuum filtration process. Subsequently, phosphorus and boron elements are separately doped into the nanotube sheet, enabling it to embody the characteristics of a PN diode. Measurements indicate that, in addition to the fundamental diode's current-voltage relationship, the device also demonstrates intriguing transmission properties under the TEM mode of electromagnetic waves. It exhibits a frequency shift of approximately 2.3125 GHz for each volt of bias change. The final result is a lightweight and flexible carbon-based semiconductor microwave filter, which can conform to curved surfaces. This feat underscores the potential of such materials for innovative and effective electromagnetic wave manipulation.
REVIEW | doi:10.20944/preprints202307.2029.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Nanobiosensing; Surface plasmon resonance; Electrochemiluminescence; Smartphone
Online: 31 July 2023 (03:45:32 CEST)
At the nanoscale, metals exhibit special electrochemical and optical properties, which play an important role in nanobiosensing. In particular, the surface plasmon resonance based on precious metal nanoparticles, as a kind of tag free biosensor technology, has brought high sensitivity, high reliability and convenient operation to the sensor detection. By applying an electrochemical excitation signal on the nano plasma device, modulating its surface electron density and realizing electrochemical coupling surface plasmon resonance, it can effectively complete the joint transmission of electrical signals and optical signals, increase the resonance shift of the spectrum, and further improve the sensitivity of the designed biosensor. In addition, smartphone is playing an increasingly important role in portable mobile sensor detection systems. These systems typically connect sensing devices to smartphone to perceive different types of information, from optical signals to electrochemical signals, providing ideas for the portability and low-cost design of these sensing systems. Among them, electrochemiluminescence, as a special electrochemical coupled optical technology, has good application prospects in mobile sensing detection due to its strong anti-interference ability, which is not affected by background light. In this review, the surface plasmon resonance is introduced from nanoparticles, and its response process is analyzed theoretically. Then, the mechanism and sensing application of electrochemistry coupled surface plasmon resonance and electrochemiluminescence are emphatically introduced. Finally, it extends to the related research of electrochemical coupled optical sensing on mobile detection platforms.
REVIEW | doi:10.20944/preprints202307.1941.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Stimuli-triggered nano-systems; hybrid nano-systems; biomimetics; bacterial infections
Online: 27 July 2023 (13:06:30 CEST)
In recent years, antimicrobial resistance in many human pathogens has become a serious health concern. Since infections with resistant pathogens cannot be treated with traditional antimicro-bial drugs, new strategies are necessary to fight bacterial infections. Hybrid nano-systems may provide a solution to this problem, by combining multiple mechanisms for killing bacteria to synergistically increase the effectiveness of the antimicrobial treatment. In this review, we high-light recent advances in the development of hybrid nano-systems for the treatment of bacterial infections. We discuss the use of hybrid nano-systems for combinational therapy, focusing on various triggering mechanisms for drug release and the development of biomimetic nanomateri-als. We also examine inherently antimicrobial nano-systems and their uses in preventing infec-tions due to wounds and medical implants. This review summarizes recent advances and pro-vides insight into the future development of antimicrobial treatments using hybrid nanomateri-als.
ARTICLE | doi:10.20944/preprints202307.1746.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Silicon nanoparticles; Li-ion battery; anode; TiO2; capacity
Online: 26 July 2023 (09:15:21 CEST)
Silicon has been proved to be one of the most promising anode materials for the next generation of lithium-ion battery. For the application in batteries, Si anode should have high capacity and must be industrially scalable. In this study, we have designed and synthesised a hollow structure to meet these requirements. All the processes are carried out without special equipment. The Si nanoparticles that are commercially available are used as the core sealed inside TiO2 shell, with rationally designed void space between the particles and shell. The Si@TiO2 are characterised using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and scanning electron microscope (SEM). The optimised hollow structured silicon nanoparticles, when used as anode in lithium-ion battery, exhibit a high reversible specific capacity over 600 mAhg-1. This excellent electrochemical property of the nanoparticles can be attributed to their optimised phase and unique hollow nanostructure.
REVIEW | doi:10.20944/preprints202307.1431.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: TMDCs; nanosheet; nanoscroll; preparation; photodetection; hydrogen evolution reaction; gas sensing
Online: 21 July 2023 (05:53:01 CEST)
Two-dimensional (2D) transition metal dichalcogenides (TMDCs) nanosheets have shown extensive applications due to their excellent physical and chemical properties. However, the low light absorption efficiency limits their application in optoelectronics. By rolling up 2D TMDCs nanosheets, the one-dimensional (1D) TMDCs nanoscrolls are formed with spiral tubular structure, tunable interlayer spacing and opening ends. Due to their increased thickness of scroll structure, the light absorption is enhanced. Meanwhile, the rapid electron transportation is confined along the 1D structure. Therefore, the TMDCs nanoscrolls show improved optoelectronic performance compared to 2D nanosheets. In addition, the high specific surface area and active edge site from bending strain of basal plane make them promising materials for catalytic reaction. Thus, the TMDCs nanoscrolls have attracted intensive attention in recent years. In this review, the structure of TMDCs nanoscrolls is firstly demonstrated and followed by various preparation methods of the TMDCs nanoscrolls. Afterwards, the applications of TMDCs nanoscrolls in the fields of photodetection, hydrogen evolution reaction, and gas sensing are discussed.
REVIEW | doi:10.20944/preprints202307.1264.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: biosynthesis; enzymatic activity; green synthesis; gold nanoparticles; silver nanoparticles
Online: 19 July 2023 (03:21:48 CEST)
Nanoparticles (NPs) have uniform chemical composition, size, and morphology. Microorganisms are of great interest in Nanoparticle synthesis. The green production of nanomaterials occurs either intracellularly or extracellularly. Gold and silver nanoparticles are mostly synthesised by the enzymatic degradation of metal ions. The produced NPs are characterized by different instruments such as ultraviolet visible, dynamic light scattering, x-ray diffraction, scanning electron microscope, transmission electron microscope, etc. Our review discusses the various biomedical applications of gold and silver nanoparticles synthesized by microbes via intracellular and extracellular mechanisms.
COMMUNICATION | doi:10.20944/preprints202307.0973.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Graphene bottom-up; non-thermal plasma synthesis; hydrocarbon to graphene
Online: 14 July 2023 (05:30:51 CEST)
Graphene is a two-dimensional nanostructured material with intrinsic properties that show promising performance in various applications, including electronics, renewable energy, medicine, mechanical enforcement and others. This study reports a bottom-up approach for the conversion of cyclohexane into graphene nanoflakes, which were then deposited onto fiberglass using a non-thermal generator. The composite was characterized using transmission electron microscopy, which revealed the formation of stacked few-layer graphene with a partially disordered structure and a d-spacing of 0.358 nm between the layers. X-ray diffraction confirmed the observations from the TEM images. SEM images showed the agglomeration of carbonaceous material onto the fiberglass, which experienced some delamination due to the synthesis method. Raman spectroscopy indicated that the obtained graphene exhibited a predominance of defects in its structure. Additionally, Atomic Force Microscopy (AFM) analyses revealed the formation of graphene layers with varying levels of porosity.
ARTICLE | doi:10.20944/preprints202307.0734.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: green method; copper oxide nanoparticles; antibacterial; ultrastructure
Online: 11 July 2023 (12:37:34 CEST)
Copper oxide nanoparticles (CuONPs) were synthesized using an eco-friendly method and their antimicrobial and biocompatibility properties were determined. The supernatant and extract of the fungus Ganoderma sessile yielded small, quasi-spherical NPs with an average size of 4.5 ± 1.9 nm and 5.2 ± 2.1 nm, respectively. CuONPs showed antimicrobial activity against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Minimum inhibitory concentration (MIC) for E. coli and S. aureus was 15.9 µg/mL for nanoparticles (NPs) using the supernatant (CuONPs-S) and 16.5 µg/ml for NPs using the extract (CuONPs-E). Lower concentrations were required for P. aeruginosa inhibition. Ultrastructural analysis revealed the presence of the small CuONPs all through the bacterial cells. Finally, the toxicity of CuONPs was analyzed in three mammalian cell lines: hepatocytes (AML-12), macrophages (RAW 264.7) and kidney (MDCK). Low concentrations (<15 µg/ml) of CuONPs-E were non-toxic to kidney cells and macrophages, and the hepatocytes were the most susceptible to CuONPs-S. The results obtained suggest that the CuONPs synthesized using the extract of the fungus G. sessile, could be further evaluated for the treatment of superficial infectious diseases.
ARTICLE | doi:10.20944/preprints202307.0314.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Artemisia absinthium; green ZnO NPs; band gap energy; plant extract; phytochemicals
Online: 5 July 2023 (12:32:59 CEST)
Artemisia absinthium (A. absinthium) leaf extract was successfully used to create zinc oxide nanoparticles (ZnO NPs), and their properties were investigated via several techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), Fourier transform infrared (FTIR), and UV–Vis spectroscopy. SEM analysis confirmed the spherical and elliptical shapes of the particles. Three different zinc peaks were observed via EDX at energies of 1, 8.7, and 9.8 keV, together with a single oxygen peak at 0.5 keV. XRD analysis identified ZnO NPs as having a hexagonal wurtzite structure with a particle size that decreased from 24.39 to 18.77 nm, and with an increasing surface area (BET) from 4.003 to 6.032 m2/g for the ZnO (without extract) and green ZnO NPs, respectively. FTIR analysis confirmed the groups of molecules that were accountable for stabilizing and minimizing the ZnO NPs, which was apparent at 3400 cm. Using UV–Vis spectroscopy, the band gap energies (Egs) for the green ZnO and ZnO (without extract) NPs were estimated, and the values were 2.65 and 2.79 eV, respectively.
ARTICLE | doi:10.20944/preprints202307.0022.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Silver/zinc oxide nanoparticles; Semiconductor; Microbial biosynthesis; Photodegradation; Cytotoxicity; Antibacterial
Online: 3 July 2023 (08:37:44 CEST)
The biological synthesis of nanoparticles has been emerging as an environmentally benign and eco-friendly method owing to its cost-effectiveness and high efficiency. Recently, the biological synthesis of semiconductor and metal-doped semiconductor nanoparticles with enhanced photocatalytic degradation efficiency and anticancer and antibacterial properties have gained tremendous attention. In pursuit of this purpose, for the first time, we biosynthesized zinc oxide (ZnO) and silver/ZnO nanocomposites (NCs) as semiconductor and metal-doped semiconductor nanoparticles, respectively, using the cell-free filtrate (CFF) of Lysinibacillus sphaericus bacterium. The biosynthesized ZnO and Ag/ZnO were characterized by various techniques such as ultraviolet-visible spectroscopy, X-ray diffraction, Fourier-transform Infrared spectroscopy, Field-emission scanning electron microscopy, transmission electron microscopy, and photoluminescence spectroscopy. The photocatalytic degradation potential of these semiconductor/metal-semiconductor nanoparticles was evaluated against the degradation of azo dye methylene blue (MB) under simulated solar irradiation. Ag/ZnO showed 90.7 ± 0.91% photocatalytic degradation of MB, compared to 50.7 ± 0.53% by ZnO in 120 min. The cytotoxicity of ZnO and Ag/ZnO on human cervical HeLa cancer cells was determined using an MTT assay. Both nanomaterials exhibited cytotoxicity in a concentration-dependent and time-dependent manner on HeLa cells. The antibacterial activity was also determined against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus). Compared to ZnO, Ag/ZnO NPs showed higher antibacterial activity. Hence, the biosynthesis of semiconductor nanoparticles could be a promising strategy for developing hybrid metal/semiconductor nanomaterials for different biomedical and environmental applications.
REVIEW | doi:10.20944/preprints202306.2208.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: APE1; DNA nanotechnology; fluorescence imaging
Online: 30 June 2023 (10:09:07 CEST)
Apurinic/apyrimidinic endonuclease 1 (APE1), also known as redox factor-1 (Ref-1), is a multifunctional protein which is widely existing in living organisms. It can specifically recognize and cleave the DNA in apurinic/apyrimidinic (AP) site in the base excision repair (BER) pathway, as well as regulate the expression of genes to activate some transcription factors. The abnormal ex-pression and disruptions in the biological functions of APE1 are linked to a number of diseases, including inflammation, immunodeficiency, and cancer. Hence, it is extremely desired to monitor the activity of APE1, acquiring a thorough understanding of the healing process of damaged DNA and making clinical diagnoses. Thanks to the advent of DNA nanotechnology, some nanodevices are used to image the activity of APE1 with great sensitivity and simplicity. In this review, we will summarize DNA nanotechnology-empowered fluorescence imaging in the past years for APE1 activity according to the types of DNA probe, which are classified into linear DNA probes, composite DNA nanomaterials and three-dimensional (3D) DNA nanostructures. We also highlight the future research directions in the field of APE1 activity imaging.
ARTICLE | doi:10.20944/preprints202306.1747.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: waste management; pest control; biopesticides
Online: 26 June 2023 (05:24:11 CEST)
Nano-emulsions of essential oils (EO) and their chemical constituents are promising raw materials for the ecological control of Tribolium castaneum. Curcuma longa Linn is a plant known for the properties of its rhizome which is used in food, health and hygiene products. Its leaves are by-products with no commercial value, but with unexplored bioactive volatile constituents. This study aims to evaluate the repellency of nano-emulsions containing the EO from leaves of C. longa or its three main chemical constituents against T. castaneum. The representative mixture of EO extracted in four different months showed p-cymene (26.0%), 1,8-cineole (15.1%) and terpinolene (15.5%) as major compounds. Nano-emulsions of EO (HLB 16.7), terpinolene (HLB 15.0), 1,8-cineole (HLB15.0) and p-cymene (HLB 15.0) were repellent at concentrations of 11 μg/cm2 (EO, terpinolene and p-cymene) and 1.1 μg/cm2 (1,8-cineole). The EO nano-emulsion droplet size increased linearly over time, remaining below 300 nm for 35 days and below 600 nm for 80 days. The EO nano-emulsion proved to be a green alternative to synthetic pesticides, as it was safe against the bioindicator Chlorella vulgaris. Terpinolene, 1,8-cineol and p-cymene were able to inhibit the enzyme telomerase from T. castaneum in an in silico assay, which may explain the repellency of these samples. This study provides ideas for the utilization of EO from leaves of C. longa as raw material of new environmentally friendly plant-derived nanobiopesticides.
ARTICLE | doi:10.20944/preprints202306.1740.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: atomic layer deposition; Hf1-xZrxO2; yttrium; crystalline phase; ferroelectric; dielectric
Online: 26 June 2023 (05:08:16 CEST)
Hf1-xZrxO2 (HZO) thin films are versatile materials suitable for advanced ferroelectric semiconductor devices. Previous studies have shown that the ferroelectricity of HZO thin films, can be stabilized by doping them with group III elements at low concentrations. While doping with Y improves the ferroelectric properties, there has been limited research on Y-HZO thin films fabricated using atomic layer deposition (ALD). In this study, we investigated the effects of Y doping cycles on the ferroelectric and electrical properties of as-deposited Y-HZO thin films with vaying compositions fabricated through ALD. The Y-HZO thin films were stably crystallized without the need for post-thermal treatment and exhibited transition behavior depending on the Y-doping cycle and initial composition ratio of the HZO thin films. These Y-HZO thin films offer several advantages, including enhanced dielectric constant, leakage current density, and improved endurance. Moreover, the optimized Y-doping cycle induced a phase transformation that resulted in Y-HZO thin films with improved ferroelectric properties, exhibiting stable behavior without fatigue for up to 1010 cycles. These as-deposited Y-HZO thin films show promise for applications in semiconductor devices that require high ferroelectric properties, excellent electrical properties, and reliable performance with a low thermal budget.
ARTICLE | doi:10.20944/preprints202306.1629.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: FRET; chitosan; nanoparticles; gelation; fluorescent probe; ovalbumin
Online: 22 June 2023 (12:49:22 CEST)
Chitosan and its derivatives as a biocompatible, biodegradable polymer that has been well-established in biotechnology and medicine as the nanogels and nanofilms forming material, has a number of practical applications in the field of the supply of medicines, food colloids, agrotechnology, as well. In this paper, the focus of attention is directed to the study of the physico-chemical principles of the formation of gels and nano-particles using fluorescence spectroscopy methods. We have obtained chitosan (Chit5) and pegylated chitosan (Chit5-PEG) particles with an average size of 170 or 400 nm, respectively by counterflow extrusion method. The paper presents three based fluorescent probes sensitive to the formation of chitosan particles: congo red, malachite green as well as covalently attached pyrene-label. Dyes fluoresce about an order of magnitude brighter in the composition of chitosan nanogel particles or in mscrogels. With these fluorescence probes, the pH- and temperature-dependent behavior of polymers was studied, and the influence of the genipin -based crosslinking agent on the gel formation parameters, such as kinetics and concentration dependence of the nanoparticles formation accompanied by sharply increases in the fluorescence intensity of dyes was evaluated. A sensitive approach for tracking gelation and including of small drug molecules and protein by FRET using a pyrene-tryptophan donor-acceptor pair is proposed using tryptophan or ovalbumin as fluorophores-donors. Upon nanogel formation FRET effect is observed manifested in sharp increase if the fluorescence intensity of the pyrene (acceptor). Thus, the application of the fluorescent probes with FRET function for monitoring the gelation and nanoparticles formation as well as drug encapsulation in chitosan-based parts, which have broad prospects in biomedical practice and food industry.
ARTICLE | doi:10.20944/preprints202306.1584.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Indium zinc sulfide; Bismuth ferrate nanofibers; S-type heterojunctions; Sulfur vacancies; Photogenerated carrier efficiency; Photocatalytic degradation
Online: 21 June 2023 (16:52:42 CEST)
Photocatalytic degradation plays a crucial role in wastewater treatment, and the key to achieving high efficiency is to develop photocatalytic systems that possess excellent light absorption, carrier separation efficiency, and surface-active sites. Among various photocatalytic systems, S-type heterojunctions have shown remarkable potential for efficient degradation. This work delves into construction of S-type heterojunctions of ternary indium metal sulfide and bismuth ferrite nanofibers with introduction of sulfur vacancy defects and morphology modifications to enhance the photocatalytic degradation performance. Through the impregnation method, BiFeO3/Zn2S4 heterojunction materials were synthesized and optimized30% BiFeO3/Zn2S4 heterojunction exhibited superior photocatalytic performance with higher sulfur vacancy concentration than Zn2S4. The in-situ XPS results demonstrate that the electrons between Zn2S4 and BFO are transferred via S-Scheme, and after modification, Zn2S4 has a more favorable surface morphology for electron transport, and its flower-like structure interacts with the nanofibers of BFO, which has a further enhancement of the reaction efficiency for degrading pollutants. This exceptional material demonstrated a remarkable 99% degradation of Evans blue within 45 min and a significant 68% degradation of ciprofloxacin within 90 min. This work provides a feasible idea for developing photocatalysts to deal with the problem of polluted water resources under practical conditions.
ARTICLE | doi:10.20944/preprints202306.1501.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Copper nanoparticles; Asparagus racemosus; Antioxidant; Anti-diabetic; Antifouling; Antibac-terial activity; Algae boom water
Online: 21 June 2023 (08:18:17 CEST)
The key objective of the experiment was to show the environmental based of copper nanoparticles which counters the growth of bacterial pathogens such as Pseudomonas aeruginosa, and Staphylococcus aureus. To begin with the experiments, root extract of Asparagus racemosus was used to synthesise Copper nanoparticles. To confirm the formation of Cu-NPs, it was subjected to characterization such as Ultra Violet analysis, X-ray Diffraction method, Fourier Transform Infrared Spectroscopy and Scanning electron microscope images. Later the antibacterial activity of Cu-NPs was studied by incorporating it into two bacterial pathogens (Pseudomonas aeruginosa and Staphylococcus aureus). The outcome displayed a satisfactory antibacterial activity against the bacterial pathogens by the biosynthesized copper nanoparticles. To boost up the enzyme inhibition property of the Cu NPs, Antioxidant and Antidiabetic assay were also performed. The biosynthesised Cu NPs displayed a satisfied result in Antifouling function. The result was used assessed with green algae bloom water.
REVIEW | doi:10.20944/preprints202306.1218.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Hybrid photovoltaic; thermal systems; carbon-based fluids; hexagonal honeycomb; PV cells
Online: 16 June 2023 (10:30:57 CEST)
All solar thermal systems, due to their thermal nature, can be hybridised or operated with both fossil fuel and solar energy. By enhancing availability and dispatch ability, hybridization has the potential to boost the value of concentrating solar thermal technology. Hybrid photovoltaic thermal systems (PV/T) offer a solution to improve on the limited capacity growth seen with standard solar panels. The analysis focuses on the creation of alternative structural and design so-lutions that may be used to boost lacking efficiency that was previously hampered by limited spectrum absorption of sun light. As a result, the spectrum is separated into two spectrum ranges, one that directly matches the bandgap of PV materials and the other that is absorbed for thermal absorption outputs. Most two channel systems are used to capture or reflect sunlight, with the layer specifically located right above the PV cell. Another layer of nanofluid is employed to evacuate heat from the PV cell, acting as the second channel, to specifically eliminate overheating difficulties. To address concerns that have arisen as a result of years of observation, the most recent study involves nano-particle-based fluids employed in PV/T, which uses a cooling medium to provide an alternate heat transfer option. Aside from nanofluids, there are phase change materials, channel alterations that result in a higher flow rate and hence improve overall performance.
ARTICLE | doi:10.20944/preprints202306.1185.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Apoptotic; Cytotoxicity; Green synthesis; Nanostructures; Scutellaria multicaulis; Silver
Online: 16 June 2023 (07:38:46 CEST)
Scutellaria multicaulis, a member of the Lamiaceae, is a medicinal plant indigenous to Iran, Afghanistan, and Pakistan. It has been widely used as a prominent herb in traditional medicine for thousands of years. This plant is reported with baicalein, wogonin, and chrysin flavonoids as a significant group of chemical ingredients, which can cure different diseases such as breast cancer. S. multicaulis leave extract was used for the bioreduction of silver nanoparticles (SmL-Ag-NPs), and their phytochemical contents and antioxidant, antibacterial, anti-proliferative, and apoptotic activity were evaluated. Optimal physicochemical properties of SmL-Ag-NPs were obtained by mixing 5% of leave extract and 2 mM of aqueous AgNO3 solution and confirmed by characterization studies including UV–visible spectrophotometry, FE-SEM, EDX, DLS, zeta potential, TGA, SERS, XRD and FTIR Spectroscopy. SmL-Ag-NPs exhibited higher content of TPC (Total Phenolic Content) and TFC (Total Flavonoid Content) and potential antioxidant activity. SmL-Ag-NPs also demonstrated dose-dependent cytotoxicity against MDA-MB231 cells multiplication with an IC50 value of 37.62 μg/mL at 48h through inducing cell apoptosis. This is the first report on the biosynthesis of silver nanoparticles using S. multicaulis leave extract, which can provide treatment for cancer diseases and reduce some negative effects of chemotherapy.
ARTICLE | doi:10.20944/preprints202306.1024.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: nanocrystalline cellulose; corn starch; nanocomposite film; virgin coconut oil
Online: 14 June 2023 (09:35:30 CEST)
Corn starch-based nanocomposite films usually have low moisture barrier properties. The addition of virgin coconut oil (VCO) as a hydrophobic component can improve the nanocomposite film's characteristics, especially the film's permeability and elongation properties. This study aimed to determine the role of VCO with various concentrations (0,3,5 wt%) on the physical, mechanical, and water vapor transmission characteristics of corn starch/NCC-based nanocomposite films. The results showed that the concentration of 3 wt% VCO was most effective in reducing the WVTR value of nanocomposite films with a value of 4.721 g/m2.h. While the value of tensile strength was 4.243 MPa, elongation 68.58%, modulus of elasticity 0.062 MPa, thickness 0.219 mm, lightness 98.77, and water solubility 40.51%. However, the addition of 5 wt% VCO was more effective in increasing the elongation properties of the film. The addition of VCO gave the appearance of a porous film surface and a finer structure was formed. The FTIR test on corn starch nanocomposite films with the addition of VCO did not show any new absorption peaks. The results of this study may provide opportunities for the development of nanocomposite films as biodegradable packaging in the future.
REVIEW | doi:10.20944/preprints202306.1004.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: semiconductor quantum dots; polymers; ligands; siloxanes; thiol-ene; quantum dots stability; quantum dots dispersion; patterning; cross linkers
Online: 14 June 2023 (07:41:26 CEST)
Patterning, stability, and dispersion of the semiconductor quantum dots (scQDs) are the three issues strictly interconnected for successful device manufacturing. Recently several authors adopted direct optical patterning (DOP) as a step forward in photolithography to position the scQDs in a selected area. However, the chemistry behind the stability, dispersion, and patterning has to be carefully integrated to obtain a functional and therefore, commercial device. In this review are described different chemical strategies suitable to stabilize the scQDs both at a single level and as an ensemble with a special focus on the ones compatible with direct optical patterning (DOP). With the same purpose, the scQDs dispersion in a matrix was described in terms of the scQDs surface ligands interactions with the matrix itself. The chemical processes behind the DOP are illustrated and discussed for five different approaches that consider together stability, dispersion, and the patterning itself of the scQDs.
ARTICLE | doi:10.20944/preprints202306.0503.v2
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Curcumin; MOF; Sodium Alginate Hydrogel; Drug Release; Antibacterial Activity
Online: 12 June 2023 (05:29:21 CEST)
Management of chronic inflammation and wounds has always been a key issue in the pharmaceutical and healthcare sector. Curcumin (CCM) is an active ingredient extracted from turmeric rhizomes that has antioxidant, anti-inflammatory, and antibacterial activities, thus showing significant effectiveness toward wound healing. However, its shortcomings such as poor water solubility, poor chemical stability and fast metabolic rate limit its bioavailability and long-term use. In this context, hydrogels appear to be a versatile matrix for carrying and stabilizing drugs due to the biomimetic structure, soft porous microarchitecture, and pleasant biomechanical properties. The drug loading/releasing efficiencies can also be controlled by use of highly crystalline and porous metal organic frameworks (MOFs). Here, a flexible hydrogel composed of sodium alginate (SA) matrix and CCM-loaded MOFs was constructed for long-term drug release and antibacterial activity. The morphology and physicochemical properties of composite hydrogels were analyzed by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), ultraviolet visible spectroscopy (UV-Vis), Raman spectroscopy and mechanical property tests. The results showed that the composite hydrogel was highly twistable and bendable to mechanically comply with human skin. The as-prepared hydrogel could capture efficient CCM for slow drug release as well as effective killing of bacteria. Therefore, such composite hydrogel is expected to provide a new management system for chronic wound dressings.
REVIEW | doi:10.20944/preprints202306.0647.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Covid-19; Coronaviruses; Personal protective equipment; Nanomaterials; PPE; SARS-CoV-2
Online: 8 June 2023 (13:19:25 CEST)
Following the well-known pandemic, declared on 30 January 2020 by the World Health Organi-zation, the request for new global strategies for the prevention and mitigation of the spread of the infection has come to the attention of the scientific community. Nanotechnology has often managed to provide solutions, effective responses, and valid strategies to support the fight against SARS-CoV-2. This work reports a collection of information on nanomaterials that have been used to counter the spread of the SARS-CoV-2 virus. In particular, the objective of this work is to illustrate the strategies that have made it possible to use the particular properties of nanomaterials, for the production of personal protective equipment (DIP) for the defense against the SARS-CoV-2 virus.
REVIEW | doi:10.20944/preprints202306.0497.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: CO2 Capture Technologies; CO2 Adsorption; Porous Silica; Amine Functionalized Porous Silica; Decarbonization.
Online: 7 June 2023 (07:19:33 CEST)
As the major greenhouse gas, CO2 gas emission has been noticeably increased over the past decades resulting in global warming and climate change. As a result, it is imperative to reduce the excess CO2 in the atmosphere to hold “the increase in the global average temperature to well below 2°C (ideally 1.5°C) above pre-industrial levels set by the Paris Agreement on climate change. Among many ways, CO2 capture technology is considered as the most promising technology among the available technologies. Porous materials such as carbons, silica, zeolites, hollow fibers, and alumina are widely used as CO2 sorbents. However, among the available porous sloid sorbents, porous silica-based materials grabbed a significant attention due to their unique properties including high surface area, pore volume, good thermal and mechanical stability, and low cost. Therefore, development of porous silica materials as a promising CO2 absorbent is a continuously expanding research area in the current moment. Herein, we aim to visualize a full picture of the porous silica-based materials for CO2 capture. This review presents a comprehensive study of existing CO2 capture techniques and highlights the recent progress of different porous silica materials and synthesis processes. CO2 adsorption capacities of unmodified porous silica materials are less effective as compared with functionalized silica materials. Various research activities have been reported about functionalization of pours silica using amine groups. Therefore, in this review, different synthesis routes of amine-functionalized porous silica materials, CO2 adsorption capacities, gas selectivity and reusability were discussed. Moreover, the research challenges associated with the porous silica materials and future research directions are summarized.
ARTICLE | doi:10.20944/preprints202306.0500.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: activated carbon; thymol; low-density polyethylene; active packaging; control release; kinetics; pork fillets; heme iron; shelf life
Online: 7 June 2023 (07:09:07 CEST)
Nowadays, bioeconomy and nanotechnology trends push food packaging sector in the re-placement of food additives by biobased antioxidant/antibacterial compounds and their inclusion in nanocarriers to control their release. Herein by following this trend, a rich in thymol-(TO) activated carbon (AC) nanostructure (TO@AC) was prepared and physiochemically characterized with various technics. This TO@AC nanostructure as well as pure AC were extruded with low density polyethylene (LDPE) to develop novel active packaging LDPE/TO@AC and LDPE/AC films. X-ray diffractometry, Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy measuraments shown high dispersity and capability of both AC and TO@AC in LDPE matrix which was resulted in enhanced tensile and water/oxygen barrier properties of obtained LDPE/AC and LDPE/TO@AC films. LDPE/TO@AC films shown higher elongation at break values and water/oxygen barrier than LDPE/AC films and significant antioxidant activity. TO release kinetics studies shown that by increasing TO@AC content the total TO amount released increased and the constant release rate decreased. Pork fillets wrapped with the optimum active film containing 15 wt.% TO@AC and succeed to prevent lipid oxidation and heme iron loss during storage. Estimation of microbial population of pork fillets shown that this active film could ex-tend the microbiological shelf-life of pork fillets by 2 days
ARTICLE | doi:10.20944/preprints202306.0442.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: perovskite; core-shell; heterostructure; stability; photocatalyst
Online: 6 June 2023 (10:13:35 CEST)
Practical applications of CsPbX3 nanocrystals (NCs) are limited by their poor stability. The formation of heterojunction between CsPbX3 NCs and oxides is an effective means to protect perovskite from polar solvents and other external factors. Significantly improving the stability and photocatalytic properties of the core/shell perovskite is very important for its application in photoelectric and photocatalytic technology. Here, we report the synthesis of asymmetrical CsPbBr3/TiO2 core-shell heterostructure NCs at single particle level by hot injection liquid phase synthesis and sol-gel method, where each CsPbBr3 NCs is partially covered by titanium dioxide. It is shown that the type II arrangement is generated at the heterogeneous interface, which greatly facilitates the separation of electron-hole pairs and increases the carrier transport efficiency. More crucial, due to the protection of titanium dioxide shell, the product has higher long-term stability in humid air compared with bare CsPbBr3 NCs. The asymmetrical core-shell heterostructure prepared in this study not only improves the stability of CsPbX3 NCs, but also provides some ideas for optoelectronic device applications and TiO2-based photocatalysts.
ARTICLE | doi:10.20944/preprints202306.0354.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: synthesis; CsPbX3; perovskite nanocrystals
Online: 5 June 2023 (16:35:12 CEST)
Compared with conventional semiconductors, halide perovskite nanocrystals (NCs) have a unique crystal structure and outstanding optoelectronic properties, which offer a wide potential for applications in optoelectronic devices such as solar cells, photodetectors, light emitting diodes, lasers and displays. Rational technological design is providing vital support for the development of perovskite optoelectronics. Herein, high-quality and monodisperse all-inorganic halide perovskite nanocrystals with consistent morphology, concentrated size distribution and cubic crystal phase were synthesized employing a modified one-pot hot injection method to independently modulate the stoichiometric ratios of three precursors involving cesium salt, lead source and halide. Mixing two kinds of perovskite NCs with different halogens, in combination with an anion exchange reaction, enables a transition from violet emission to green and finally to red emission over the entire visible region. Our work will be applied to enhance optoelectronic properties and stability of all-inorganic perovskite NCs for serving as light-emitting components in optoelectronic devices, as well as expanding the application areas of perovskite semiconductors for photocatalytic hydrogen generation, CO2 reduction and dye degradation.
ARTICLE | doi:10.20944/preprints202306.0324.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: porous gold nanoparticles; plasmons, optical absorption,; dewetting, dealloying; support-free nanoparticles
Online: 5 June 2023 (13:20:35 CEST)
3D metal nanostructures are often the basis of several applications such as in catalysis, plasmonics, medical diagnosis, therapy, drug screening, ophthalmologic, and biomedical applications. Porous gold nanoparticles (PGNs) are intensively investigated due to their outstanding morphological as well as advantageous optical properties. Unfortunately, the thermal stability of these open-porous structures is poor, i.e. even as a result of low-temperature annealing (150$^\circ$C in air), their porosity disappears and they lose their favorable optical properties. In order to preserve their beneficial properties, a thin metal oxide coating can be applied. Changing the coating's thickness and/or composition, the optical response of the PGNs can also be tuned in a wide wavelength region. Moreover, these nanoparticles can be synthesized also in support-free form, which makes them more attractive from an application point of view. This review article summarizes some of the preparation modes of these complex nanostructures (fixed and support-free), as well as their thermal stability and optical responses.
ARTICLE | doi:10.20944/preprints202306.0268.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Magnetic nanoparticles; cobalt ferrite; barium ferrite; additive manufacturing; VAT Photopolymerization
Online: 5 June 2023 (08:25:47 CEST)
Additive Manufacturing and nanotechnology have been used as basic tools for the manufacture of nanostructured parts with magnetic properties to expand the variety of applications in additive processes by tank photopolymerization. Magnetic cobalt ferrite (CoFe2O4) and barium ferrite (BaFe12O19) nanoparticles with the size distribution of average value DTEM of 12 ± 2.95 nm and 37 ± 12.78 nm, respectively were generat-ed by hydroxide precipitation method. The dispersion of the nanoparticles on commercial resins (Anycubic Green and IRIX White resin) was obtained by mechanochemical reactions carried out in an agate mortar for 20 minutes, at room temperature and with limited exposure to light. The product of each reaction was placed in amber vials, also being kept in a box, to avoid contact with light. The photopolymerization process was carried out only at low concentrations (w/w % nanoparticles/resin) since, at high concentrations, there is no for-mation of pieces due to the high refractive index of ferrites. Raman shift spectroscopy of the final pieces showed that they contain the magnetic nanoparticles, with no apparent chemical changes. The EPR results of the pieces maintain the magnetic properties and apparently, they are not modified during the photopolymer-ization. Although significant differences were found in the dispersion process of the nanoparticles in each piece, we determined that the photopolymerization did not influence the structure and superparamagnetic behavior of ferrite nanoparticles during processing, and the magnetic properties were successfully transferred to the final 3D-printed magnetic obtained piece.
REVIEW | doi:10.20944/preprints202305.2196.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Nanocellulose; Cellulose Nanofibrils; Cellulose Nanocrystals; Bacterial Nanocellulose; Energy Storage
Online: 31 May 2023 (08:14:34 CEST)
Primary materials supply is the heart for engineering and sciences; depletion of natural resources and an increase in the human population by a billion in 13 to 15 years pose a critical concern on the sustainability of the materials. Therefore, functionalizing renewable materials, such as nanocellulose, possibly exploiting its properties for various practical applications, has been undertaken worldwide. Nanocellulose has emerged as a dominant green natural material with attractive and tailorable physicochemical properties, renewable, sustainable, biocompatibility, and tunable surface properties. Nanocellulose is derived from cellulose, the most abundant polymer in nature with remarkable properties of nanomaterials. This article provides a comprehensive overview of the methods used for nanocellulose preparation, structure-property and processing-property correlations, and the application of nanocellulose and its nanocomposite materials. This article differentiates the classification of nanocellulose, provides a brief account of the production methods that have been developed for isolating nanocellulose, highlights a range of unique properties of nanocellulose that have been extracted from different kinds of experiments and studies; and elaborates on nanocellulose potential applications in various areas. The present review is anticipated to provide the readers regarding the progress and knowledge related to nanocellulose. Pushing the boundaries of nanocellulose further into cutting edge applications will be of particular interest for the future, especially as cost-effective commercial sources of nanocellulose continue to emerge.
REVIEW | doi:10.20944/preprints202305.2057.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Nanoparticles; catalysis; metal chalcogenide; ternary metal chalcogenide; quaternary metal chalcogenide
Online: 30 May 2023 (05:43:18 CEST)
Inorganic chemistry has contributed to the progress of human civilization in several different ways. Its activities at the interface with other scientific disciplines has led to emergence of several new fields like organometallic chemistry, bio-inorganic chemistry, solid-state chemistry, environmental chemistry, etc. In the past few decades, it has made inroads in yet another dimension of immense relevance, i.e. nano-science and –technology. In this assay an attempt has been made to present an overview of utility of inorganic and organometallic compounds as precursors for the synthesis of nano-materials with reference to catalysis and materials science. Applications of metal nanoparticles (NPs) and metal chalcogenide NPs, generated through molecular precursor route, in catalysis have been discussed. Synthesis of ternary and quaternary metal chalcogenide nano-materials by molecular precursor route has been reviewed.
ARTICLE | doi:10.20944/preprints202305.1768.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: corrole; phthalocyanine; gas sensor; organic heterojunction; conductometric transducer; molecular material
Online: 25 May 2023 (08:31:03 CEST)
The versatility of metal complexes of corroles raised the interest in the use of these molecules as element of chemical sensors. The tuning of the macrocycle properties by synthetic modification of the different components of the corrole ring, such as functional groups, molecular skeleton, and coordinated metal, allows the creation of a vast library of corrole-based sensors. However, the scarce conductivity of most of aggregates of corroles limits the development of simple conductometric sensors and requires the use of optical or mass transducers that are rather more cumbersome and less prone to be integrated in microelectronics systems. To compensate the scarce conductivity, corroles are often used to functionalize the surface of conductive materials such as graphene oxide, carbon nanotubes, or conductive polymers. Alternatively, they can be incorporated in heterojunction devices where they are interfaced with a conductive material such as a phthalocyanine. Herewith, we introduce two heterojunction sensors made of junctions of lutetium bisphthalocyanine (LuPc2) with either 5,10,15-tris(pentafluorophenyl) corrolato Cu (1) or 5,10,15-tris(4-methoxyphenyl)corrolato Cu (2). Optical spectra show that after forming the heterojunction, corroles maintain their original structure. The conductivity of the devices reveals an energy barrier for interfacial charge transport, which is larger in the 1/LuPc2 device. The different interfacial barriers is also manifested by the opposite response respect to ammonia: with a 1/LuPc2 behaving as a n-type conductor and 2/LuPC2 as a p-type conductor. Furthermore, the sensors show a high sensitivity respect to relative humidity with a reversible and fast response in the range 30-60%.
ARTICLE | doi:10.20944/preprints202305.1706.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Ion current rectification; Multi-layer; Bipolar ionic diode; Nanochannel network membrane; Nanoparticle
Online: 25 May 2023 (08:07:26 CEST)
Ion current rectification (ICR) is the ratio of ion current by forward bias to by backward bias and is a critical indicator of diode performance. In previous studies, many attempts have been continued to improve the performance of this ICR, but there is the intrinsic problem for geometric changes that induce ionic rectification due to their fabrication problem. Additionally, the high ICR could be achieved in the narrow salt concentration range only. Here, we propose a multi-layered bipolar ionic diode based on an asymmetric nanochannel network membrane (NCNM), which is realized by soft lithography and self-assembly of homogenous-sized nanoparticles. Owing to the freely changeable geometry based on soft lithography, the ICR performance can be explored according to the variation of microchannel shape. Interestingly, very stable ICR performance can be achieved using the multi-layered 3D configuration for the bipolar diode in a broad range of salt concentrations (0.1mM ~ 100 mM). This demonstrates the promising potential of multi-layered NCNM for applications in highly concentrated electrolytes, such as biosensors, desalination, or energy harvesting.
ARTICLE | doi:10.20944/preprints202305.1385.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: smart drug delivery system; nanomaterials; poly(methacrylic acid); photoluminescence
Online: 19 May 2023 (05:39:42 CEST)
Nanomaterials such as pH-responsive polymers are promising for targeted drug delivery systems, due to the difference in pH between tumor and healthy regions. However, there is a significant concern about the application of these materials in this field due to their low mechanical resistance, which can be mitigated by combining these polymers with mechanically resistant inorganic materials such as mesoporous silica nanoparticles (MSN) and hydroxyapatite (HA). Mesoporous silica has interesting properties such as high surface area and hydroxyapatite has been widely studied to aid in bone regeneration, providing special properties adding multifunctionality to the system. Furthermore, fields of medicine involving luminescent elements such as rare earth are an interesting option in cancer treatment. The present work aims to obtain a pH-sensitive hybrid system based on silica and hydroxyapatite with photoluminescent and magnetic properties. The nanocomposites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nitrogen adsorption methods, CHN elemental analysis, Zeta Potential, scanning electron microscopy (SEM), and transmission electron microscopy (TEM), vibrational sample magnetometry (VSM), and photoluminescence analysis. Incorporation and release studies of the antitumor drug doxorubicin were performed to evaluate the potential use of these systems in targeted drug delivery. The results showed the luminescent and magnetic properties of the materials and showed suitable characteristics for application in the release of pH-sensitive drugs.
REVIEW | doi:10.20944/preprints202305.1287.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: bifunctional; catalysis; nanoparticle; zeolite; biomass
Online: 18 May 2023 (07:26:49 CEST)
Bifunctional catalysts consisting of mono- or bimetallic nanoparticles (NPs) and zeolite supports received considerable attention due to excellent catalytic properties in numerous reactions including direct and indirect biomass processing. Here, we discuss major approaches to the preparation of NPs in zeolites, concentrating on methods allowing the best interplay (synergy) between metal and acid sites which is normally achieved for small NPs well-distributed through zeolite. We focus on modification of zeolites to provide structural integrity and controlled acidity which can be accomplished by incorporation of certain metal ions or elements. The other modification avenue is the adjustment of the zeolite morphology including creation of numerous defects for the NP entrapment and designed porosity. In this review we also provide examples of synergy between metal and acid sites and emphasize that without density functional theory calculations many assumptions about interactions between active sites stay unvalidated. Finally, we describe the most interesting examples of direct and indirect biomass (waste) processing for the last five years.
ARTICLE | doi:10.20944/preprints202305.1220.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: ZnO; nanoparticle size; in vitro; cytotoxicity; hemolysis; protein corona
Online: 17 May 2023 (10:06:00 CEST)
This study describes a comparative in vitro study of the toxicity behavior of zinc oxide (ZnO) nanoparticles and micro-sized particles. The study aimed to understand the impact of particle size on ZnO toxicity by characterizing the particles in different media, including cell culture media, human plasma, and protein solutions (bovine serum albumin and fibrinogen). The study used various techniques such as atomic force microscopy (AFM), transmission electron microscopy (TEM), and dynamic light scattering (DLS) to characterize the particles and their interactions with proteins. Hemolytic activity, coagulation time, and cell viability assays were used to assess ZnO toxicity. The results highlight the complex interactions between ZnO NPs and biological systems, including their aggregation behavior, hemolytic activity, protein corona formation, coagulation effects, and cytotoxicity. Moreover, the study indicates that ZnO nanoparticles are not more toxic than micro-sized particles, and the 50 nm particles resulted in general the least toxic. Furthermore, the study found that at low concentrations, no acute toxicity was observed. Overall, this study provides important insights into the toxicity behavior of ZnO particles and highlights that no direct relationship between nanometer size and toxicity can be directly attributed.
REVIEW | doi:10.20944/preprints202305.0658.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Nanotechnology application; nano-suspension techniques; nano-emulsion techniques; bioactive constituents of plant; phytochemicals (PHYs); poor water solubility; drug delivery systems (DDSs); toxicological risks of NPs; clinical application of NPs
Online: 9 May 2023 (12:50:27 CEST)
The awareness of the existence in plants of bioactive compounds namely phytochemicals (PHYs), having health properties is progressively expanding. Therefore, their massive introduction in the normal diet, in food supplements, and their use as natural therapeutics to treat several diseases are increasingly emphasized by several sectors. Particularly, most PHYs possessing antifungal, antiviral, anti-inflammatory, antibacterial, antiulcer, anti-cholesterol, hypoglycemic, immunomodulatory, and antioxidant properties have been isolated from plants. Additionally, their secondary modification with new functionalities, to further improve their intrinsic beneficial effects, is extensively investigated. Unfortunately, although the idea of exploiting PHYs as therapeutics is amazing, its realization is far from simple, and the possibility of exploiting them as effective orally administrable drugs is almost utopic. Most PHYs are insoluble in water and, when introduced orally, they scarcely reach the site of action in therapeutic concentrations. Degradation by enzymatic and microbial digestion, occurring in the mouth, stomach, and intestine, as well as fast metabolism and rapid excretion via the kidney, biliary, or lung, strongly limit their in vivo activity. To overcome these drawbacks, several nanotechnological approaches have been used and many PHYs-loaded delivery systems with dimensions of nanometers have been developed. This paper, also by reporting various recent case studies, reviews the foremost nano-suspension and nano-emulsion-based techniques developed for formulating the most relevant PHYs in more bioavailable nanoparticles (NPs), suitable or promising for clinical application. Also, the acute and chronic toxic effects due to the exposure to NPs reported so far, the possible nanotoxicity which could derive by their massive employment, as well as the ongoing actions to improve the knowledge in the field were discussed. The state of the art concerning the actual clinical application of both PHYs and the nanotechnologically engineered PHYs was also reviewed.
ARTICLE | doi:10.20944/preprints202305.0617.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: dry reforming; methane; ceria-zirconia; supercritical synthesis; oxygen vacancies; stability
Online: 9 May 2023 (08:53:37 CEST)
This work is devoted to the study of active and stable nickel catalysts for methane dry reforming based on Pr-doped ceria-zirconia obtained by solvothermal continuous method. The studies of physicochemical and catalytic properties of the 5%Ni\Ce0.75Zr0.25-xPrxO2 series showed that Pr introduction leads to an increase in the amount of highly reactive oxygen of the oxide lattice. Praseodymium-based catalysts showed significantly higher reactant conversions. In addition to the nature of support, the method of nickel introduction was also studied - Ni was added both by impregnation and one-pot with mixed oxide preparation. The method of Ni addition was shown to have significant effect on the morphology of the supported active component and, respectively, on the catalytic activity. The 5%Ni/Ce0.75Zr0.15Pr0.1O2 catalyst prepared by one-pot method showed stable operation in the MDR reaction for 30 hours at CO2 and CH4 conversions of ~40% and an H2 yield of ~18% (Т=700°С, τ=10ms).
ARTICLE | doi:10.20944/preprints202305.0454.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Cs2CuCl4 nanocrystals; Ag passivation; photoluminescence quantum yield; stability
Online: 8 May 2023 (05:22:15 CEST)
Lead-free copper halide perovskite nanocrystals (NCs) are emerging materials with excellent photoelectric properties. Herein, we present a colloidal synthesis route of orthorhombic Cs2CuCl4 NCs with well-defined cubic shape and an average diameter of 24 ± 2.1 nm. The Cs2CuCl4 NCs exhibit bright deep blue photoluminescence, which is attributed to the Cu(II) defects. In addition, passivating the Cs2CuCl4 NCs by Ag+ can effectively improve the photoluminescence quantum yield (PLQY) and environmental stability.
REVIEW | doi:10.20944/preprints202305.0289.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: cancer therapy; nanomedicine; drug delivery; pH-responsiveness; EPR; intratumoral delivery; intracellular delivery; nanoparticles; metal-organic frameworks
Online: 5 May 2023 (03:45:54 CEST)
The paradigm of drug delivery via nano- and microcarriers is one of the leading ideas that enable overcoming the limitations of traditional chemotherapy. The trend toward more complex drug carriers capable of multifunctionality is observed in the literature. To date, prospects of stimuli-responsive systems to control the cargo release in the lesion nidus are widely accepted. Both endogenous and exogenous stimuli are employed for this purpose, however, endogenous pH is one of the most common triggers. Unfortunately, scientists face difficulties in the implementation of this idea since a range of biological barriers, drug bioavailability issues, and challenges in the synthesis of carriers with required properties have arisen. Here, we discuss fundamental strategies of pH-responsive drug delivery as well as limits in its application and reveal the main problems, weak sides, and reasons for poor clinical results. Also, we have made an attempt to formulate the profiles of "ideal" drug carrier in the frame of different strategies and considered recently published studies through the lens of these profiles. This approach enables the identification of current trends and promising vectors in the development of pH-responsive drug delivery systems, as well as challenges to be resolved in the next generation of carriers.
ARTICLE | doi:10.20944/preprints202305.0233.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: hafnium oxide; graphene nanowalls; plasma-enhanced chemical vapor deposition; photodetectors
Online: 4 May 2023 (08:26:12 CEST)
Graphene/silicon (Si) heterojunction photodetectors are widely studied in detecting of optical signals from near-infrared to visible light. However, performance of the graphene/Si photodetectors is limited by defects created in the growth process and surface recombination at the interface. Herein, a remote plasma-enhanced chemical vapor deposition is introduced to directly grow graphene nanowalls (GNWs) at a low power, which can effectively improve the growth rate and reduce defects. Moreover, hafnium oxide (HfO2) grown by atomic layer deposition has been employed as an interfacial layer for the GNWs/Si heterojunction photodetector. It is shown that the high-k dielectric layer of HfO2 acts as an electron blocking and hole transport layer, which minimizes the recombination and reduces dark current. By optimizing the thickness of HfO2, an extremely low dark current of 3.85×10^(-10) A with a responsivity of 0.19 AW^(-1), as well as a specific detectivity of 1.38×10^12 Jones at zero bias can be obtained for the fabricated GNWs/HfO2/Si photodetector. This work demonstrates a universal strategy to fabricate high-performance graphene/Si photodetectors.
REVIEW | doi:10.20944/preprints202305.0180.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Green Chemistry; Vegetable oils; Bio-based nanoparticles; Oncology APIs
Online: 4 May 2023 (04:04:06 CEST)
Latterly, the development of green synthesized polymeric nanoparticles with anticancer studies has been an emerging field in academia, and in the pharmaceutical and chemical industry. Vegetable oils are potential substitutes for petroleum derivatives, as they present themselves as a clean and environmentally friendly alternative and are available in high quantities at relatively low prices. Biomass-derived chemicals can be converted into monomers with unique structures, generating materials with new properties for the synthesis of sustainable monomers and polymers. In this way, the production of bio-based polymeric nanoparticles appears as a great application of green chemistry for biomedical uses. There is an increasing demand for biocompatible and biodegradable materials for specific applications in biomedical as cancer therapy, encouraging scientists in working on research towards designing polymers, with enhanced properties and clean processes, containing oncology active pharmaceutical ingredients (APIs). The nanoencapsulation of these APIs in bio-based polymeric nanoparticles can control the release of the substances, increase bioavailability, reduce problems with volatility and degradation, reduce side effects, and increase treatment efficiency. Thus, this review aims to discuss the use of green chemistry for bio-based nanoparticle production and its application in anticancer medicine. The use of vegetable oils for the production of renewable monomers and polymers will be discussed, bringing castor oil as an ideal candidate for such application, as well as more suitable methods for the production of bio-based nanoparticles and some oncology APIs available for anticancer application.
REVIEW | doi:10.20944/preprints202305.0176.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: inorganic fluorescent hydrogel; fluorescent nanocrystal; biosensor
Online: 4 May 2023 (03:48:53 CEST)
Fluorescent hydrogels are promising candidate materials for portable biosensors to be used in point-of-care diagnosis because (1) they have a greater capacity for binding organic molecules than immunochromatographic test systems, determined by the immobilization of affinity labels within the three-dimensional hydrogel structure; (2) fluorescent detection is more sensitive than the colorimetric detection of gold nanoparticles or stained latex microparticles; (3) the properties of the gel matrix can be finely tuned for better compatibility and detection of different analytes; and (4) hydrogel biosensors can be made reusable and suitable for studying dynamic processes in real time. Water-soluble fluorescent nanocrystals are widely used for in vitro and in vivo biological imaging due to their unique optical properties, and hydrogels based on them allow preserving these properties in bulk composite macrostructures. Here we review the techniques for obtaining analyte-sensitive fluorescent hydrogels based on nanocrystals, the main methods used for detecting the fluorescent signal changes, and the approaches to the formation of inorganic fluorescent hydrogels via sol–gel phase transition using surface ligands of the nanocrystals.
ARTICLE | doi:10.20944/preprints202305.0018.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Diclofenac; nanoformualtion; lipid-core nanocapsules; adjuvant arthritis; stereology; cartilage; synovial membrane
Online: 1 May 2023 (04:46:33 CEST)
Introduction: Diclofenac is the most prescribed non-steroidal anti-inflammatory drug worldwide and used to reliev pain and inflammation for inflammatory arthritis. Diclofenac do not slows disease progression and cartialge damage of Rheuamtoid Arthritis individuals. Moreover, it associated with seriuos adverse effects even using regular dose regimens. Drug delivery systems can overcome this issues reducing adverse effects and optmizing efficacy. Objectives: to evaluate the activity of a lipid-core nanocapsule loaded of Diclofenac (DIC-LNC) in an experimental model of adjuvant-induced arthritis and its anti-arthritic properties at the joint components. Methods: The diclofenac nanoformulation was obtained by self-assembling methodology. The stereology analysis aproach was applied for morphological quantification of the volume, density and cellular profile count of the metatarsophalangeal joints of rats induced to adjuvant arthritis. Proinflamatory cytokines and biochemical profile was also obtained. Results: DIC-LNC is able to reduce arthitis compared to control group (p<0.0001) and DIC group (p=0.009). The TNF and IL1 cytokine as well as C-reative protein and Xanthine-oxidade were efficiently reduced by DIC-LNC. Additionally, DIC-LNC reduces synovites and condrocytes lossing compared to DIC (p<0.05)and control group (p<0.05). The synovial space volume was higher for DIC-LNC compared to DIC (p<0.05) and Control (p<0.05). These data are suggesting that DIC-LNC is showing anti-arthritic actvity preserving deep joint components. Conclusion: DIC-LNC is a promissing nanoformulation for clinical use, since is able to reduce joint inflamation and synovits, avoiding damage of cartilage and synovial space at advjuvant athrits. Further studies and developments are necessary to achieve future clinical use.
ARTICLE | doi:10.20944/preprints202304.1211.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Uranyl Cations; Dendritic Polymers; Silica Xerogels; Composites; Nanoparticles; water purification; radioactive wastewater; Uranium removal; Dendrimers; Biomimetic
Online: 29 April 2023 (04:48:19 CEST)
Two different silica conformations (Xerogels and Nanoparticles) both formed by the mediation of dendritic poly (ethylene imine) were tested at low pHs on the problematic uranyl cation sorption. The effect of crucial factors i.e., temperature, electrostatic forces, adsorbent composition, accessibility of the pollutant to the dendritic cavities and MW of the organic matrix was investigated to conclude the optimum formulation for water purification under these conditions. This was attained with the aid of UV-Visible and FTIR spectroscopy, dynamic light scattering (DLS), ζ-potential; Brunauer–Emmett–Teller (BET) porosimetry, Thermo Gravimetric Analysis (TG) and Scanning Electron Microscopy (SEM) Results highlighted that both adsorbents have extraordinary sorp-tion capacity. Xerogels are cost-effective since they approximate the performance of na-noparticles with much lesser organic content. Furthermore, they are more practicable materials since they may penetrate the pores of a metal or ceramic solid substrate in the form of a precursor, gel-forming solution.
ARTICLE | doi:10.20944/preprints202304.1191.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Graphene; Pulsed Laser deposition; nanocrystallization
Online: 29 April 2023 (03:00:18 CEST)
The wide application of graphene in the industry requires the direct growth of graphene films on silicon substrates. In this study, we find a possible technique to meet the requirement above. Multilayer graphene thin films (MLG) are grown without a catalyst on Si/SiO2 by pulsed laser deposition (PLD). It was found that the minimum number of laser pulses that are required to produce fully covered (uninterrupted) samples is 500. This number of laser pulses resulted in samples that contain ~5 layers of graphene. The number of layers was not affected by the laser fluence and the sample cooling rate after the deposition. However, the increase of the laser flu-ence from 0.9 J/cm2 to 1.5 J/cm2, results in 2.5 fold reduction of the MLG resistance. The present study reveals that the PLD method is suitable to produce nanocrystalline multilayer graphene with electrical conductivity of the same magnitude as commercial CVD graphene samples.
ARTICLE | doi:10.20944/preprints202304.1079.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Sol-gel; surfactant; nanoparticles; calcium hydroxide; nano-solutions; alkali-activated materials
Online: 27 April 2023 (13:06:59 CEST)
This work presents the production and incorporation of calcium hydrolyzed nano-solutions at three concentrations (1, 2, and 3 wt.%) in alkali-activated gold mine tailings (MTs) from Arequipa, Perú. A first activator solution of sodium hydroxide (NaOH) at 10M was used. The calcium hy-drolyzed nano-solutions acted as a secondary activator and as additional calcium resource for the alkali-activated materials (AAMs) based on the low-calcium gold MTs. High-resolution trans-mission electron microscopy/energy-dispersive x-ray spectroscopy (HR-TEM/EDS) analyses were carried out to characterize the morphology, size, and structures of the calcium hydrolyzed na-noparticles. Fourier transform infrared (FTIR) analyses then were used to understand the chemical bonding interactions in the calcium hydrolyzed nanoparticles and in the AAMs. Scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS) and Quantitative X-ray diffraction (QXRD) were performed to study the structural, chemical, and phase compositions of the AAMs; uniaxial compressive tests evaluated the compressive strength of the reacted AAMs; and Nitrogen adsorption-desorption analyses measured the porosity changes at nanostructure level in the AAMs. The results indicate that each increase in the concentration of the calcium hydrolyzed nano-solution had a direct/proportional effect on the mechanical properties of the AAMs samples. The AAMs with 3 wt.% calcium-hydrolyzed nano-solution had the highest compressive strength value of 15.16 MPa, which represented an increase of 62% compared to the original system without nanoparticles and aged under the same conditions of 70°C for seven days. These results provide useful information about the positive effect of calcium-hydrolyzed nanoparticles on gold MTs and their conversion into sustainable building materials through alkali activation.
ARTICLE | doi:10.20944/preprints202304.1009.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Ag nanoparticles; Ag-TiO2 nanoparticles; cotton fabrics; photocatalytic activity; biocide activity; E. coli; S. aureus
Online: 27 April 2023 (03:05:20 CEST)
Composites of Ag and TiO2 nanoparticles on cotton fabrics were synthetized in-situ by sono-chemical and hydrothermal methods achieving the successive formation of Ag-NPs and Ti-NPs directly on the fabric. The impregnated fabrics were characterized by ATR-FTIR spectroscopy, high resolution microscopy (HREM), scanning electron microscopy coupled with Ener-gy-dispersive X-ray spectroscopy (SEM-EDS), Raman, photoluminescence, UV-vis and DRS spectroscopies and by tension tests. Results showed the successful formation and impregnation of NPs on the cotton fabric, with a negligible leaching of NPs after several washing cycles. The photocatalytic activity of supported NPs was assessed by the degradation of methyl blue dye (MB) under solar and UV irradiation revealing improved photocatalytic activity of the Ag-TiO2/cotton composites due to a synergy of both Ag and TiO2 nanoparticles. This behavior is attributed to a diminished electron-hole recombination effect in the Ag-TiO2 cotton samples. The biocide activity of these composites on the growth inhibition of Staphylococcus aureus (Gram+) and Escherichia coli (Gram-) was confirmed, revealing interesting possibilities for the utilization of the functionalized cotton fabric as protective cloth for medical applications.
REVIEW | doi:10.20944/preprints202304.0927.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Poly/perfluoroalkyl substances; advanced reductive processes; advanced oxidation processes; nanomaterials; water treatment
Online: 25 April 2023 (11:46:29 CEST)
This review focus on a critical analysis of nanocatalysts for Advanced Reductive Processes (ARP) and Oxidation Processes (AOP) designed for the degradation of poly/perfluoroalkyl substances (PFAS) in water. Ozone, ultraviolet and photocatalyzed ARP and/or AOP will be the basic treatment technologies. Besides the review of the nanomaterials with greater potential as catalyst for advanced processes of PFAS in water, the perspectives for its future development considering sustainability considerations will be discussed. Moreover, a brief analysis of the current state of the art of the ARP and AOP for the treatment of PFAS in water will be presented.
REVIEW | doi:10.20944/preprints202304.0334.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Cyclodextrin; , host-guest inclusion; drug delivery; interactions; application
Online: 14 April 2023 (02:52:22 CEST)
Drug delivery systems consist of cyclodextrins (CyDs) have kept constant attention for good compatibility, negligible toxicity, and improved pharmacokinetics of drugs. The unique hollow structure has endowed a lot of functions, such as inclusion of guest molecules, functional modification of active hydroxyl groups, and noncovalent interactions. Besides, the polyhydroxy structure has further extended the functions of CyDs by inter/intramolecular interactions and chemical modification. Furthermore, the versatile functions of the complex contribute to physicochemical characteristics alteration of the drugs, therapeutic talent, stimulus-responsive switch, self-assemble capability, and fiber formation. This review attempts to list the recent progress of CyDs and discuss their roles in the drug delivery system. Future perspectives of the construction of CyD-based drug delivery systems are also discussed at the end of this review, which may be the possible directions for the construction of more rational and cost-effective delivery vehicles.
ARTICLE | doi:10.20944/preprints202304.0244.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Propane dehydrogenation; metal oxide; alumina; spinel
Online: 12 April 2023 (05:41:38 CEST)
Co-based catalysts have gained significant attention in recent years due to their excellent ability to activate C-H bonds and high selectivity towards olefins, despite being a non-noble and environmentally unfriendly metal. However, further improvements are necessary for practical utilization, particularly in terms of activity and anti-carbon deposition capacity. In this study, we synthesized Al2O3 nanorods with abundant pentacoordinated Al3+ (Al3+penta) sites. The supported Co on the Al2O3 nanorod (Co/Al2O3-NR) exhibited higher selectivity (>96% propylene selectivity) and stability (deactivation rate 0.15 h-1), compared to Co supported on an Al2O3 nanosheet with fewer pentacoordinated Al3+ sites. Various characterizations confirmed that Co(II) mainly exists as CoAl2O4 rather than Co3O4 in the form of Co/Al2O3-NR, which inhibits the reduction of Co(II) to Co0 and improves catalyst stability accordingly.
REVIEW | doi:10.20944/preprints202304.0229.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: vitamins; nanoencapsulation; nanodispersions; phospholipid vesicles; liposomes; cosmetics; food application
Online: 12 April 2023 (02:54:13 CEST)
Liposomes have been used for several decades for the encapsulation of drugs and bioactives in cosmetics and cosmeceuticals. On the other hand, the use of these phospholipid vesicles in food applications is more recent and has been increasing significantly in the last ten years. Although in different stages of technological maturity - in the case of cosmetics, many products are on the market - processes to obtain liposomes suitable for the encapsulation and delivery of bioactives are highly expensive, especially aiming at scaling-up. Among the bioactives proposed for cosmetics and food applications, vitamins are the most frequently used. Despite the differences between the administration routes (oral for food and mainly dermal for cosmetics), some challenges are very similar (e.g., stability, bioactive load, average size, increase of drug bioaccessibility and bioavailability). In the present work, a systematic review of the technological advancements in the nanoencapsulation of vitamins using liposomes and related processes was performed; challenges and future perspectives were also discussed in order to underline the advantages of these drug loaded biocompatible nanocarriers for cosmetics and food applications.
ARTICLE | doi:10.20944/preprints202303.0528.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: nano-cellulose; nanocomposites; mechanical properties; biopolymers
Online: 30 March 2023 (12:31:40 CEST)
It is important to add second- or third-phase materials to improve the physical, mechanical, and biodegradable properties of polypropylene (PP) nanocomposites. A unique hybrid bio-nanocomposite was fabricated using microparticle cellulose powder from wastepaper with a polypropylene (PP) polymeric matrix using a low-shear chaotic mixing method. A small amount (2-5%) of layered micro clay was also added to investigate the hybrid effect of nanocomposite fabrication on the mechanical properties. A low-shear chaotic melt mixing method induces the formation of nano cellulose structures and layered clay nanoparticles by via exfoliation. The nanoparticles were characterized using Fourier transform infrared (FTIR) spectroscopy. Mechanical properties such as the flexural strength (FS) and tensile strength (TS) were investigated using an Izod impact tester (IZ), and a dynamic mechanical testing analyzer (DMTA). Further, scanning electron microscopy (SEM) was used to observe the microstructure of the nanocomposite. In addition, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were conducted to investigate the crystallinity and degradation of the samples, respectively. The addition of wastepaper cellulose powder below 2.5 wt. % did not improve the mechanical properties, however, improvements were observed when more than 5wt.% wastepaper cellulose powder was added. With the addition of a small amount of nano-clay, the mechanical properties were significantly improved, and a synergistic effect could be noticed. The observed results were then compared with PP-clay nanocomposites used in automotive industries to replace cellulose nanocomposites. The application areas can also cover lead production in paper cups and vacuum foaming.
ARTICLE | doi:10.20944/preprints202302.0459.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: copper ferrite; magnetic properties; anion-exchange resin precipitation; magnetic nanoparticles
Online: 27 February 2023 (08:38:56 CET)
Copper ferrite attracts a lot of interest from researchers as a material with unique magnetic, optical, catalytic and structural properties. In particular, the magnetic properties of this material are structurally sensitive and can be tuned by changing the distribution of Cu and Fe cations in octahedral and tetrahedral positions by controlling synthesis parameters. In this study, we propose a new simple and convenient method for the synthesis of copper ferrite nanoparticles using a strongly basic anion exchange resin in OH form. The effect and possible mechanism of polysaccharides addition on the elemental composition, yield and particle size of CuFe2O4 is investigated and discussed. It is shown that anion exchange resin precipitation leads to a mixture of unstable at standard temperature cubic (c-CuFe2O4) and stable tetragonal (t-CuFe2O4) phases. The effect of the reaction conditions on the c-CuFe2O4 stability is studied by temperature-dependent XRD measurements and discussed in terms of the cations distribution, Jahn−Teller distortion and Cu2+ and oxygen vacancies in the copper ferrite lattice. The obtained differences in the values of saturation magnetization and the coercive force of prepared samples are explained with a reference to variations in the particle sizes and the structural characteristics of copper ferrite.
REVIEW | doi:10.20944/preprints202302.0451.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: graphene oxide (GO); reduced graphene oxide (rGO); biosensors; pesticides; detection
Online: 27 February 2023 (07:03:26 CET)
Pesticides are often used in different applications including agriculture, forestry, aquaculture, food industry, etc in order to insect pests and weeds. The indiscriminate usage of pesticides poses a massive threat to food, environmental and human health safety. Hence, the fabrication of a sensitive, and reliable sensor for the detection of pesticide residues in agro products and environmental samples is a critical subject to be considered. Recently, the graphene family including graphene oxide (GO) and reduced graphene oxide (rGO) have been frequently employed in the construction of sensors owing to their biocompatibility, high surface area to volume ratio, and excellent physiochemical, optical, and electrical properties. The integration of bio-recognition molecules with GO/rGO nanomaterials offers a promising detection strategy with outstanding repeatability, signal intensity, and low background noise. This review focuses on the latest developments (2018 to 2022) in the different types of GO/rGO-based biosensors such as surface plasmon resonance (SPR), fluorescence resonance energy transfer (FRET) and electrochemical based techniques, etc for pesticide analysis. The critical discussions on the advantages, limitations, and sensing mechanisms of emerging GO/rGO-based biosensors have been highlighted as well. Additionally, we explore the existing hurdles in GO/rGO-based biosensors, such as handling of difficult biological samples, reducing the total cost, and so on. This review also provides research gaps and viewpoints for future innovations in GO/rGO-based biosensors for pesticide determination mainly in areas with insufficient resources.
ARTICLE | doi:10.20944/preprints202302.0418.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: SPION; multimodal nanoparticles; PET diagnosis; MRI; 44/47Sc; PSMA-617; prostate cancer
Online: 24 February 2023 (04:36:10 CET)
This study was performed to synthesize multimodal radiopharmaceutical designed for the diagnosis and treatment of prostate cancer. To achieve this goal, Super Paramagnetic Iron Oxide (SPIO) nanoparticles were used as a platform for targeting molecule (PSMA-617) and for complexation of two scandium radionuclides, 44Sc for PET imaging and 47Sc for radionuclide therapy. TEM and XPS images showed that the Fe3O4 NPs have a uniform cubic shape and a diameter from 38 to 50 nm. The Fe3O4 core are surrounded by SiO2 and an organic layer. The saturation magnetization of the SPION core was 60 emu/g. However, coating the SPIONs with silica and polyglycerol reduces the magnetization significantly. The obtained bioconjugates were labeled with 44Sc and 47Sc, with a yield higher than 97%. The radiobioconjugate exhibited high affinity and cytotoxicity towards the human prostate cancer LNCaP (PSMA+) cell line, much higher than for PC-3 (PSMA-) cells. High cytotoxicity of the radiobioconjugate was confirmed by radiotoxicity studies on LNCaP 3D-spheroids. In addition, the magnetic properties of the radiobioconjugate should allow for its use in guide drug delivery driven by magnetic field gradient.
ARTICLE | doi:10.20944/preprints202302.0365.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: cyclic dipeptides; biopolymers; electrospinning; photoluminescence; nanofibers; energy harvesting
Online: 22 February 2023 (02:03:20 CET)
Nanostructured dipeptide self-assemblies exhibiting quantum confinement are of great interest due to their potential applications in the field of materials science as optoelectronic materials for energy harvesting devices. Among those, aromatic cyclo-dipeptides containing the amino acid tryptophan are wide-band gap semiconductors displaying high mechanical rigidity, photoluminescence and piezoelectric properties to be used in power generation. In this work, we report the fabrication of hybrid systems based on chiral cyclo-dipeptide L-Tryptophan- L-Tryptophan incorporated into biopolymer electrospun fibers. The micro/nanofibers contain self-assembled nanospheres embedded into the polymer matrix are wide-band gap semiconductors (gap energy 3.8 eV), display blue photoluminescence and relevant piezoelectric and pyroelectric properties with coefficients as high as 57 pCN-1 and 35×10-6 Cm-2k-1, respectively. They are therefore promise systems for thermal sensing and energy harvesting applications.
ARTICLE | doi:10.20944/preprints202302.0308.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: adsorption; photocatalysis; kinetics; ZnO; nanoparticle
Online: 17 February 2023 (09:19:50 CET)
In this work, the adsorption and photocatalytic properties of ZnO-ZnAl2O4 nanosized composites synthesized by the polymer-salt method have been studied. To evaluate the efficiency of adsorption, experiments were carried out on the decolorization of aqueous solutions of the Chicago Sky Blue diazo dye. The adsorption process is divided into two stages, at the first stage the dye is rapidly adsorbed on the outer surface of the composite particles, at the second stage the dye diffuses into the pores of the material. It was noted that the rate of photocatalytic decomposition of the dye is higher than the rate of the adsorption process, which indicates the occurrence of photocatalytic decomposition of dye molecules both on the surface of the composites and in the liquid phase. With an increase in the light intensity, the photocatalytic process is significantly accelerated, linearly at low intensities, and at high intensities the dependence becomes a power law.
COMMUNICATION | doi:10.20944/preprints202302.0168.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: carboxymethyl cellulose; cerium oxide; nanocomposite; cerium nanoparticles; stabilization; microscopy
Online: 9 February 2023 (11:35:13 CET)
Nanocomposites consisting of cerium based nanoparticles stabilized by carboxymethyl cellulose (CMC) macromolecules were obtained using one-pot reaction at room tempera-ture. The characterization of the nanocomposites was carried out with the use of combina-tion of microscopy, XRD and IT-spectroscopy analysis. The type of crystal structure of in-organic nanoparticles corresponding to CeO2 has been determined and the mechanism of the nanoparticles formation was suggested. It was demonstrated that the size and shape of nanoparticles in the resulting nanocomposites does not depend on the ratio of the ini-tial reagents. Spherical particles with mean diameter 3 nm were obtained in different reac-tion mixtures. The scheme of the dual stabilization of CeO2 nanoparticles with carboxylate and hydroxyl groups of CMC. These findings are promising for the development and ap-plication of Ce-based nanoparticles materials.
ARTICLE | doi:10.20944/preprints202301.0544.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: microplastics; nanoplastics; TiO2; crystallinity; film; photocatalysis; degradation; mitigation; microplastic pollution.
Online: 30 January 2023 (07:06:32 CET)
Microplastics (MPs) and nanoplastics (NPs) are distributed and transferred among the four major environmental compartments (air, water, soil, and biota) and have been already found in humans, making crucial to develop remediation technologies to tackle this kind pollution. Photocatalysis can be used to eliminate MPs present in contaminated wastewater effluents before their discharge into waterbodies. In this work, several green TiO2-based semiconductors were prepared using the extrapallial fluid (EPF) of Mytilus edulis sea water mussels as doping precursor. The semiconductors were then used as films or powders to photocatalytically degrade polystyrene (PS) NPs and MPs and polyethylene (PE) MPs. It was found that the obtention of green TiO2-based semiconductors with good characteristics for photocatalytic purposes (anatase crystalline phase, presence of porosity, activity in visible light and high surface area) seems not enough to achieve high degradation efficiency. The operational conditions of the reaction system should be also taken into account. For instance, the convenience of using semiconductors in the form of films can be overcome by their limited exposed surface area or the null adsorption of the semiconductor in the MPs particles. Additionally, crystallinity of the semiconductor can be a more determinant factor to take into account when performing photocatalysis of MPs.
ARTICLE | doi:10.20944/preprints202301.0453.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Arabic gum; nanocomposite; melanin; optical properties; silver nanoparticles
Online: 25 January 2023 (10:12:27 CET)
Abstract composite silver nanoparticles were synthesised using melanin broth and Arabic gum as a reducing and binding agent. The reactions are carried out with water because it is a non-hazardous solvent. The produced composites either had specified diameters (average diameter of 50 nm) with high silver loading or lower loading composites with tuneable morphologies and electrical properties. UV-IR, gamma, and conventional light are used to characterise the synthesised composite silver nanoparticles. Furthermore, measurements are carried out of the dielectric constant, refractive index, energy gap, optical and electrical conductivities, and refractive index coefficients. The silver nanoparticle formation was validated by UV-Vis measurement of the sample, which demonstrated a distinct peak at a wavelength of 420 nm. The characteristics of the composite silver nanoparticles are also quantified using several methods, including XRD, SEM, and particle size analysis.
REVIEW | doi:10.20944/preprints202301.0432.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Water splitting; LDH materials; Hydrogen evolution reaction; Oxygen evolution reaction; Electrocatalytic performance
Online: 24 January 2023 (13:18:37 CET)
Water splitting technology is an efficient approach to generate hydrogen (H2) energy, which can well address the problems of environmental deterioration and energy shortage, as well as establishment of a clean and sustainable hydrogen economy powered by renewable energy sources due to the green reaction of H2 with O2. While the efficiency of H2 production by water splitting technology is intimately related with the reactions on electrode. Nowadays, the efficient electrocatalysts in water splitting reactions are the precious metal-based materials, i.e., Pt/C, RuO2 and IrO2. Ni (Co, Fe)-based layered double hydroxides (LDH) 2D materials are the typical non-precious metal-based materials in water splitting with advantages of low cost, excellent electrocatalytic performance and simple preparation methods, which exhibits a great potential for the substitution for precious metal-based materials. This review summarizes the recent progress of Ni (Co, Fe)-based LDH 2D materials for water splitting, which mainly focuses on discussing and analyzing the different strategies to modify LDH materials towards high electrocatalytic performance. We also discuss the recent achievements including their electronic structure, electrocatalytic performance, catalytic center, preparation process and catalytic mechanism. Furthermore, the characterization progress in revealing electronic structure and catalytic mechanism of LDH is highlighted in this review. Finally, we put forward some future perspectives related to design and explore advanced LDH catalysts in water splitting.
ARTICLE | doi:10.20944/preprints202301.0351.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: X-ray luminescence; solvothermal synthesis; LaF3:Ce; Zeta-potential; PEG; PVP; PEI
Online: 19 January 2023 (09:13:37 CET)
A series of LaF3:Ce3+ phosphors for the application in photodynamic therapy is synthesized using a one-stage solvothermal synthesis. The conditions providing the maximum intensity of UV- and X-ray-excited luminescence, lowest size and highest colloidal stability of the phosphor nanoparticles are found to respectively include cerium content 5% mol., use of ethanol as the reaction medium for the solvothermal synthesis and addition of polyvinylpyrrolidone as a stabilizer in an optimized amount.
REVIEW | doi:10.20944/preprints202301.0330.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: applications; biogenic; environment; remediation; silver; soil
Online: 18 January 2023 (09:17:08 CET)
The invention of nanoscience not only brings a revolutionary change in the field of science but also changed the direction of research. Today the whole world is under the trigger of nano and nanoparticles have multidimensional applications in every aspect of life including environmental point of view. Till today a plethora of nanoparticles have been synthesized and have also been applied for multiple purposes and hence grabbed the attention of researchers all over the world. Among the bunch of NPs discovered to date, we have a particular interest in silver nanoparticles (AgNPs) because of their cost-effectiveness and huge abundance in the earth’s crust. With respect to every passing day, due to various kinds of anthropological activities, the quality of the environment such as air, water and soil is depleting which ultimately hampers the human civilization. To encompass the growing environmental issues, many techniques have been adopted. Among the many strategies, tackling the current issues regarding environment through nanoscience is highly worthy as because of its cost-effectiveness, less time consuming and easy handling process. This article reviews the potential of nanoparticles, particularly silver nanoparticles, for a wide range of environmental applications, such as soil, air, and water remediation.
ARTICLE | doi:10.20944/preprints202301.0172.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Solid-state supercapacitors, flexibility, transferability, energy storage, SECM
Online: 10 January 2023 (03:42:21 CET)
Transparent conductive electrodes (TCEs) are of enormous significance to the emergence of flexible and wearable electronics and continued growth of modern devices. Versatile and tunable TCEs, featuring with not only high optical transmittance but also intriguing features of electrochemical energy-storage capability, remain a significant challenge. Here we develop capacitive active films comprised of graphene-conjugated V2O5@poly (3,4-ethylene dioxythiophene) ternary composite (V2O5@PEDOT/rGO) on silver nanowire coated substrates as solid-state super/pseudocapacitors. The constructed electrodes exhibit improved electrolyte ions interaction with effective graphene layer, achieving high areal capacitance 0.6-1.2 mF.cm−2 with 0.5M LiCl electrolytes at optical transparency >60% with record durability. As demonstrated, the kinetic blocking of PEDOT layer and anchoring capability of graphene upon amphoteric soluble vanadium ions from layered V2O5 nanoribbons/nanobelts contribute synergistically to the unusual electrochemical stability, also shown using scanning electrochemical microscopy (SECM) providing electroactivity sites and ion transportation rates. As-fabricated symmetric solid-state supercapacitors delivered broad potential window >1.4 V under two different electrolyte environments (aqueous LiCl and LiCl/PVA gel) and demonstrated higher power and energy density (0.27 μWh.cm−2) outperforming previously reported devices at <0.1 μWh.cm−2. The electrochemical properties are also discussed in terms of solvation in polymer gel electrolyte ions.
REVIEW | doi:10.20944/preprints202301.0053.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: gastrin releasing peptide receptor; GRPR; bombesin receptor subtype 2; BB2; bombesin; targeted therapy; molecular imaging; theranostics; nanotechnology; nanoparticle; nanomedicine
Online: 4 January 2023 (03:19:26 CET)
Advances in nanomedicine bring the attention of researchers to the molecular targets which can play a major role in the development of novel therapeutic and diagnostic modalities for cancer management. The choice of a proper molecular target can decide on the efficacy of the treatment and endorse the personalized medicine approach. Gastrin-releasing peptide receptor (GRPR) is a G-protein-coupled membrane receptor, well known to be overexpressed in numerous malignancies including pancreatic, prostate, breast, lung, colon, cervical and gastrointestinal cancers. Therefore, many research groups express a deep interest in targeting GRPR with their nanoformulations. A broad spectrum of the GRPR ligands has been described in the literature, which allows tuning of the properties of the final formulation, particularly in the field of the ligand affinity to the receptor and internalization possibilities. Hereby the recent advances in the field of applications of various nanoplatforms which are able to reach the GRPR expressing cells are reviewed.
ARTICLE | doi:10.20944/preprints202212.0583.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: light trapping; Si solar cells; ablation; dry etch; Lambertian limit
Online: 30 December 2022 (10:14:28 CET)
Ultra-short 230 fs laser pulses of 515 nm wavelength were tightly focused into 700 nm focal spots and utilised in opening ~ 0.4 − 1 μm holes in alumina Al2O3 etch masks with 20-50 nm thickness. Such dielectric masks simplify fabrication of photonic crystal (PhC) light trapping patterns for the above-Lambertian performance of high efficiency solar cells. Conditions of laser ablation of transparent etch masks and effects sub-surface Si modifications were revealed by plasma etch- ing, numerical modeling, and minority carrier lifetime measurements. Mask-less patterning of Si is proposed using fs-laser direct writing for dry plasma etch of Si.
ARTICLE | doi:10.20944/preprints202212.0521.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: multi-modal sensing devices; PDAC; reduced graphene oxide; layer-by-layer deposition; temperature monitoring; relative humidity measurements; volatile organic compounds; electrochemical sensing
Online: 28 December 2022 (01:18:48 CET)
Precise monitoring of different environmental parameters and contaminations during food processing and storage is a key factor for maintaining its safety and nutritional value. Thus, developing reliable, efficient, cost-effective sensor devices for these purposes is of utmost importance. In this paper, we show that Poly-(diallyl-dimethylammonium chloride)/reduced Graphene oxide (PDAC/rGO) films produced by a simple Layer-by-Layer deposition can be effectively used to monitor temperature, relative humidity and the presence of volatile organic compounds as indicators for spoilage odors. At the same time, they show potential for electrochemical detection of organophosphate pesticide dimethoate. By monitoring the resistance/impedance changes during temperature and relative humidity variations or upon the exposure of PDAC/rGO films to methanol, good linear responses were obtained in the temperature range of 10-100 °C, 15-95 % relative humidity, and 35 ppm - 55 ppm of methanol. Moreover, linearity in the electrochemical detection of dimethoate is shown for the concentrations in the order of 102 µmol dm−3. The analytical response to different external stimuli and analytes depends on the number of layers deposited, affecting sensors’ sensitivity, response and recovery time, and long-term stability. The presented results could serve as a starting point for developing advanced multimodal sensor devices and sensor arrays with high potential for analytical applications in food safety and quality monitoring.
ARTICLE | doi:10.20944/preprints202212.0514.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: nano-alloy; Si-Cr; Si nano-needles; sub-100 nm; nanoscale
Online: 27 December 2022 (08:41:50 CET)
Ultra-short 230 fs laser pulses of 515 nm wavelength were tightly focused into 700 nm focal spots and utilised in opening ~ 400 nm nano-holes in a Cr etch mask that was tens-of-nm thick. Nano-holes ablated at slightly above the threshold of ablation irradiance became nano-disks and nano-rings at slightly lower pulse energies. Subtle sub-1 nJ pulse energy control was harnessed to pattern large surface areas with controlled nano-alloying of Si and Cr. This technique is extendable to vacuum-free large area patterning of nanolayers by alloying them at distinct locations with sub-diffraction resolution. Such metal masks with nano-hole opening can be used for formation of random patterns of nano-needles with sub-100 nm separation when applied to dry etching of Si.
ARTICLE | doi:10.20944/preprints202212.0505.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: coupled quantum dots; InAs/GaAs; tunneling effect; exciton; biexciton; Talbot effect; optical lattice
Online: 27 December 2022 (02:52:52 CET)
Talbot effect is a self-imaging or lensless imaging phenomenon of a periodic grating illuminated by a collimated light beam at regular distances from the grating. Research on the Talbot effect has recently made significant strides thanks to the quick development of optical superlattices. The emergence of various applications of this effect in fields such as optics, acoustics, X-ray, plasmonics, and information processing has led to the increasing importance of obtaining a Talbot carpet with the use of different structures. In this paper, we investigate the Talbot effect that originates from the tunneling effect between an ensemble of vertically coupled cylindrical quantum dots (QDs). The Talbot carpet can be manipulated by changing the parameters of the QD system. In the current paper, two modified Pöschl-Teller potentials were used to model the QDs ensemble. The exciton’s lifetime and tunneling time’s dependence on the first QD’s potential half-width is found for a fixed value of the external electric field. The nonlinear changes in the refractive index and absorption spectrum dependent on the tunneling effect are obtained. Afterward, the Talbot carpet formation is investigated, particularly the dependences of the formed periodic wavefront’s visibility on medium length, coupling field’s strength, and tunneling parameter. Finally, we have observed the intensity distribution of the diffraction field at Talbot half-distance.
ARTICLE | doi:10.20944/preprints202212.0436.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Green synthesis, antibacterial PPT, iron oxide nanoparticles, orange peel extract, cytotoxicity, superparamagnetic behavior.
Online: 23 December 2022 (02:15:06 CET)
Magnetic nanoparticles based on iron oxides (MNPs-Fe) with magnetite or maghemite phases have been widely employed in bio-applications. Thus, they have been used as contrast agents in magnetic resonance imaging (MRI) and oncological treatments through different therapies. Besides, due to the vast health problem of multidrug-resistant bacterial infections, several studies have proposed MNPs-Fe as photothermal agents (PTAs) within antibacterial photothermal therapy (PTT). This work presents a quick and easy green synthesis (GS) to obtain MNPs-Fe using orange peel extract from orange waste from local commerce, which presents an environmentally friendly approach compared to traditional methods such as coprecipitation. The GS can be irradiated with microwaves to reduce the synthesis time drastically. We evaluated the weight yield of the GS and the physical-chemical and magnetic features of the synthesized MNPs-Fe. Besides their cytotoxicity in animal cell line ATCC RAW 264.7, their antibacterial activity against Staphylococcus Aureus (S. Aureus) and Escherichia Coli (E. Coli) was assessed. We found that the MNPs-Fe synthesized using the GS, with 50% v/v of NH4OH and 50% v/v of orange peel extract (50GS-MNPs-Fe) had an excellent weight yield, negligible cytotoxicity for concentrations of MNPs-Fe below 250 µg·mL-1 in 24 hours, and 8 days. In the MNPs-Fe surface, we identified a coating of organic molecules (~ 25 nm) such as terpenes, aldehydes, etc. MNPs-Fe inhibited S. Aureus and 2.54 log10 (CFU) of E. Coli under red LED light irradiation (630 nm, 65.5 mW·cm-2, 30 min). Likewise, they exhibited a superparamagnetic (SPM) behavior for temperatures above 60 K, with a size of 49.3±9.6 nm and saturation magnetization (Ms) of 72.83 and 44.16 emu·g-1 at 60 and 300 K, respectively. Therefore, 50GS-MNPs-Fe are excellent candidates as broad-spectrum PTAs in antibacterial PTT, magnetic hyperthermia (MH), or MRI.
ARTICLE | doi:10.20944/preprints202212.0435.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: biopolymers; nanoparticles; garlic essential oil; packaging
Online: 23 December 2022 (02:01:47 CET)
Edible films were produced combining pectin (P) matrix with chitosan nanoparticle (CSNP), polysorbate 80 (T80), and garlic essential oil (GEO) as an antimicrobial agent. The CSNP were analyzed for their size and stability, and the films, throughout their contact angle, scanning electron microscopy (SEM), mechanical and thermal properties, WVP and antimicrobial activity. Four filming-forming suspension were investigated: PGEO (control); PGEO@T80; PGEO@CSNP; PGEO@T80@CSNP. The average particle size was 317nm with zeta potential reaching +21.4 mV, which indicated colloidal stability. The wettability of the films exhibited values of 65°, 43°, 78°, 64° respectively. In antimicrobial tests, the films containing GEO showed inhibition only by contact for S.aureus. For E. coli, the inhibition occurred only in films containing CSNP and by direct contact in the culture. The results indicate a promising alternative for designing stable antimicrobial nanoparticles for application in novel food active packaging.
ARTICLE | doi:10.20944/preprints202211.0394.v2
Subject: Chemistry And Materials Science, Nanotechnology Keywords: permanent magnets; hexaferrites; magnetic nanocomposites; nanomagnets; epitaxy; exchange coupling; shape anisotropy
Online: 15 December 2022 (07:03:38 CET)
Herein, we demonstrate the synthesis of sandwiched composite nanomagnets, which consist of hard magnetic Cr-substituted hexaferrite cores and magnetite outer layers. The hexaferrite plate-like nanoparticles with average dimensions of 36.3 nm × 5.2 nm were prepared by glass crystallization method and were covered by spinel-type iron oxide via thermal decomposition of iron acetylacetonate in hexadecane solution. The hexaferrite nanoplates act as seeds for the epitaxial growth of the magnetite, which results in uniform continuous outer layers on both sides. The thickness of the layers can be adjusted by controlling the concentration of metal ions. In this way, layers with average thickness of 3.7 and 4.9 nm were obtained. Due to an atomically smooth interface the magnetic composites demonstrate the exchange coupling effect, acting as single phases during remagnetization. The developed approach can be applied to any spinel-type material with matching lattice parameters and opens the way to expand the performance of hexaferrite nanomagnets due to a combination of various functional properties.
ARTICLE | doi:10.20944/preprints202212.0239.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: plasmonics; plasmonics photodetector; focused ion beam; silicon photodiode; near-infrared; LiDar.)
Online: 13 December 2022 (11:01:47 CET)
Recently, the interest in silicon-based detectors capable of detecting single photons in the near-infrared is growing mainly due to LiDAR applications, autonomous driving in particular. Silicon single-photon avalanche diodes are one of the most interesting single-photon NIR technology available on the market, nevertheless, their efficiency is hindered by the low absorption coefficient of Si in the NIR. The idea is the integration of CMOS-compatible nanostructures, specifically, silver grating array supporting Surface Plasmons Polaritons (SPPs), to confine superficially the incoming NIR photons and therefore increase photons probability to generate an electron-hole pair. The plasmonic silver array is geometrically fine-tuned using time domain simulation software to achieve maximum detector performance at 950 nm. Then, the plasmonic silver array is integrated by means of the focused ion beam technique on the detector. Finally, the integrated detector is electro-optically characterized, demonstrating a quantum efficiency of 13 at 950 nm, 2,2 times more than the reference detector. This result suggests the production of a device capable of detecting single NIR photons, at a very low cost and compatible with CMOS, thus integrable on existing technology platforms.
REVIEW | doi:10.20944/preprints202212.0112.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: Gastro retentive drug delivery systems; non-effervescent systems; floating drug delivery systems; microballoons; CRDDS
Online: 7 December 2022 (02:26:58 CET)
Gastro-retentive floating microspheres were developed as a result of the recent advancements in floating delivery systems for drugs (FDDS), which included the uniform dispersion of multiparticulate dosage forms along the GIT. This could lead to more consistent drug absorption and a lower risk of local irritation. Microballoons (MB), a multi-unit extended release with a sphere-shaped cavity encased in a tough polymer shell, have been developed as a dosage form with exceptional buoyancy in the stomach. This preparation for constrained intestinal absorption is made to float on top of gastric acid, that has a relative density lower than 1.By using enteric acrylic polymers and the emulsion solvent diffusion method, microballoons are prepared and filled to drug in one‘s outer polymer casings. Enteric acrylic plastics are used to generate microballoons that are drug-loaded in one‘s external polymer casings and dissipate in a solution of dichloromethane and ethanol. Cavity development in microparticles seems to be particularly correlated with dichloromethane evaporation. Microballoons with a drug distributed or dispersed all through the particle-matrix have the potential for a controlled drug release and float continuously for more than 12 hours in vitro out over the surface of an acidified dissolution medium with surfactant. The drug is released slowly and at the desired rate as the microballoons glide over the components of the stomach, increasing gastro-retention time and lowering fluctuations in plasma concentration.
ARTICLE | doi:10.20944/preprints202212.0085.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: diamond; synthesis; diphthalocyanine; pyrolyzate; lanthanide; X-ray; luminescence
Online: 6 December 2022 (01:35:19 CET)
Diamond powders with inclusions of europium atoms were synthesized at high pressure (7.7 GPa) and temperature (1800oC) from a mixture of pentaerythritol, C(CH2OH)4, and pyrolyzate of diphthalocyanine (C64H32N16Eu) served as a special precursor. In prepared diamonds by X-ray fluorescence spectroscopy, we have found the concentration of Eu atoms of 51±5 ppm that is by two orders of magnitude greater than that in known natural and synthetic diamonds. X-ray diffraction, SEM, X-ray exited optical luminescence, Raman and IR spectroscopy have confirmed the formation of diamond monocrystals of high quality with em-bedded Eu atoms and a nitrogen content of ~500 ppm. Numerical simulation has allowed us de-termine the energy cost of 5.8 eV needed for the incorporation of a single Eu atom with adjacent vacancy into growing diamond crystal (528 carbons).
ARTICLE | doi:10.20944/preprints202212.0076.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: mechanical alloying; titanium carbide; spark plasma sintering; cermets; corrosion
Online: 5 December 2022 (11:30:50 CET)
In order to produce nanostructured Ti0.9Cr0.1C powders, an elemental powder mixture of titanium, chromium, and graphite is milled in this work using a high-energy ball mill for various milling times. Microstructural characteristics such as crystallite size, microstrain, lattice parameter, and dislocation density are determined using X-ray diffraction (XRD). Mechanical alloying successfully produced nanocrystalline (Ti,Cr)C with an average crystallite size of 11 nm. This size of the crystallites is also directly verified using transmission electron microscopy (TEM). Scanning electron microscopy (SEM) was used to investigate the morphology of the samples. The novelty of this work is advancing the scientific understanding of the effect of milling time on the particle size distribution and crystalline structure, and also understanding the effect of the spark plasma sintering on the different properties of the bulks. Densified cermet samples were produced from the nanocrystalline powders, milled for 5, 10 and 20 hours by SPS process at 1800 degrees for 5 min under a pressure of 80 MPa. Phase changes of the produced cermets were examined according to XRD, SEM/EDX analyses. Significant amounts of Cr and Fe elements were detected, especially in the 20 h milled cermet. The bulk forms of the milled powders for 5 and 20 h had a relative density of 98.43 and 98.51 %, respectively. However, 5 h milled cermet had 93.3 HRA because of the more homogeneous distribution of the (Ti,Cr)C phase, the low iron content and high relative density. According to the 0.0011 mm/year corrosion rate, and 371.68 kΩ*cm2 charge transfer resistance obtained from the potentiodynamic polarization and EIS tests, the 20 h cermet was the specimen with the highest corrosion resistance.
COMMUNICATION | doi:10.20944/preprints202212.0060.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: exosomes; extrusion; proteolipid nanoparticles; drug delivery; nanomedicine; doxorubicin; ex-truded nanoparticles; hydroxychloroquine; endolysosomal escape; lysosomotropic
Online: 5 December 2022 (06:04:21 CET)
Because of their high biocompatibility, stability, ability to negotiate biological barrier passage, and functionalization properties, biological nanoparticles have been actively investigated for many medical applications. Biological nanoparticles, including natural extracellular vesicles (EVs) and synthetic extracellular vesicle-mimetic nanovesicles (EMNVs) represent novel drug delivery vehicles that can accommodate different payloads. In this study, we investigated EVs and EMNVs for their physical, biological and delivery properties and we showed that EMNVs have similar delivery properties compared to EVs. In addition, these nanotherapeutics were analyzed for their cytostatic properties in combination with the FDA-approved drug hydroxychloroquine (HCQ), which increased their cytostatic thanks to its lysosome-destabilizing properties. Altogether, these data demonstrated that, at least in vitro, the use of synthetic biomimetic particles is comparable to the natural counterparts, while their synthesis is significantly faster and more cost effective. In addition, we highlighted the benefits of combining biological nanoparticles with a lysosome destabilizing agent that increased the delivery properties of the particles.
ARTICLE | doi:10.20944/preprints202212.0013.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: poly(lactic-co-glycolic acid); silica; nanoparticles; enzymes; amino acid depletion; cancer; drug delivery; double emulsion; biocompatible
Online: 1 December 2022 (07:56:18 CET)
Some cancer cells rely heavily on non-essential biomolecules for survival, growth, and proliferation. Enzyme based therapeutics can eliminate these biomolecules, thus specifically targeting neoplastic cells; however, enzyme therapeutics are susceptible to immune clearance, exhibit short half-lives, and require frequent administration. Encapsulation of therapeutic cargo within biocompatible and biodegradable poly(lactic-co-glycolic acid) nanoparticles (PLGA NPs) is a strategy for controlled release. Unfortunately, PLGA NPs exhibit burst release of cargo shortly after delivery or upon introduction to aqueous environments where they decompose via hydrolysis. Here we show the generation of hybrid silica-coated PLGA (SiLGA) NPs as viable drug delivery vehicles exhibiting sub-200 nm diameters, a metastable Zeta potential, and high loading efficiency and content. Compared to uncoated PLGA NPs, SiLGA NPs offer greater retention of enzymatic activity and slow the burst release of cargo. Thus, SiLGA encapsulation of therapeutic enzymes, such as asparaginase, could reduce frequency of administration, increase half-life, and improve efficacy for patients with a range of diseases.
REVIEW | doi:10.20944/preprints202211.0494.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: SnO2 NPs and their nanocomposites; Photocatalysis; Supercapacitors; Antibacterial activities
Online: 28 November 2022 (04:43:28 CET)
Tin (IV) oxide nanoparticles (SnO2 NPs) have received a lot of interest because of their interesting features. SnO2 NPs have proven productive in a range of fields, including water purification, supercapacitors, batteries, antibacterial and antioxidant agents, and others. SnO2-based nanoparticles found a wide range of applications after incorporating materials with varying chemical compositions. SnO2 NPs and their nanocomposites have been used effectively as antibacterial agents against various pathogenic bacteria, photocatalysts for dye degradation, and electrode materials for supercapacitors (SCs). This article covers the characteristics of SnO2 NPs, SnO2 nanocomposite materials, applications of SnO2 NPs and their composite materials, including antibacterial, energy storage, and photocatalysis, as well as some significant recent studies.
ARTICLE | doi:10.20944/preprints202211.0475.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: single-atom catalysts; graphene; activity; reactivity; stability; Pourbaix plots
Online: 25 November 2022 (10:06:33 CET)
Understanding the catalytic performance of different materials is of crucial importance for further technological advancements. This especially relates to the behavior of different classes of catalysts under operating conditions. Here we analyze the effects of local coordination of metal centers (Mn, Fe, Co) in graphene-embedded Single-Atom Catalysts (SACs). We have started from well-known M@N4-graphene catalysts and systematically replaced nitrogen atoms with oxygen or sulfur atom to obtain M@OxNy-graphene and M@SxNy-graphene SACs (x+y=4). We show that local coordination strongly affects the electronic structure and the reactivity towards hydrogen and oxygen species. However, the stability is even more affected. Using the concept of Pourbaix plots, we show that the replacement of nitrogen atoms coordinating metal center with O or S destabilizes SACs towards the dissolution, while the metal centers get easily covered by O and OH acting as additional ligands at high anodic potentials and high pH values. Thus, not only should local coordination be considered in terms of the activity of SACs, but it is also necessary to consider its effects on the speciation of SACs' active centers under different potential and pH conditions.
ARTICLE | doi:10.20944/preprints202211.0411.v1
Subject: Chemistry And Materials Science, Nanotechnology Keywords: nanocomposites; degree of aggregation; analytical modelling; percolation threshold
Online: 22 November 2022 (07:57:34 CET)
Fiber aggregation in nanocomposites has an important effect on the macroscopic electrical performance. To quantitatively evaluate its effect, an index to characterize the degree of aggregation is imperative, and ideally it should have three features simultaneously, i.e., single-parametric, dimensionless and physically meaningful, applicable to different aggregation topologies, and one-to-one corresponding to material electrical properties. To this end, a new aggregation degree is proposed, which is defined as the average increased number of fibers that connect with each one when fibers aggregate from a uniformly distributed state. This index is applicable to different aggregation topologies from lump-like aggregating clusters to network-like aggregating clusters. This index is proven to only depend on the local features of aggregating clusters, and can be concisely expressed by the characteristic parameters of local structure, via geometric probability analysis and numerical validations. Further, a one-to-one linear relation between the aggregation degree and percolation threshold is established by Monte Carlo simulations, which is independent of the distribution law of the fibers. This work provides a guide to the property characterization, performance prediction and material design of nanocomposites, and also gives a physical insight into the understanding of systems with similar non-uniform distributions.