ARTICLE Download: 73| View: 317| Comments: 0 | doi:10.20944/preprints201904.0299.v1
Subject: Materials Science, Biomaterials Keywords: X-ray diffraction; bioactivities; cytotoxicity test; Anti-cancer activities
Online: 26 April 2019 (11:00:21 CEST)
Owing to fascinating applications of ZnO in modern devices, it is interesting to explore its more features for future devices. Hence, herein, we have synthesized the high quality ZnO spherical nanoparticles (SNPs) through a facile green synthesis route and robust structural and biomedical studies are carried out. Hexagonal phase with 93.2% crystallinity was confirmed through XRD analysis. ZnO nanoparticles were tested for their bioactivities both in vivo (acute cytotoxicity test) and in vitro (Anti-cancer activities on liver (HepG2) and cervical (Hela) cancer cell lines, stimulatory/inhibitory effects on normal rat splenic cells and hemolytic effects on red blood cells). Results showed that ZnO SNPs has no cytotoxic effects on vital organ like liver and has no hemolytic action on red blood cells. ZnO SNPs showed inhibitory consequence on normal rat splenic cells growth at all tested concentrations. ZnO nanoparticles showed an inhibitory effect on HepG2 cell line. While showed stimulatory effect on Hela cell line. Current study presents the synthesized ZnO SNPs as highly applicable in bio-optoelectronics.
Sat, 13 April 2019
COMMUNICATION Download: 51| View: 107| Comments: 0 | doi:10.20944/preprints201904.0151.v1
Subject: Materials Science, Biomaterials Keywords: ISFETs; ISE; polyurethane; salivary nitrate; stress; drift; ion-selective membrane
Online: 13 April 2019 (05:06:44 CEST)
We have studied on the stress measurement by making use of salivary nitrate, which can be a candidate of stress markers, with ion-selective field-effect transistors (ISFETs). ISFETs are suitable for on-site single-drop analysis of salivary nitrate within 10 seconds. However, when ISFETs are used for salivary nitrate, ISFETs have a problem which is called the initial drift. The initial drift makes it difficult for determination of an accurate nitrate monitoring. Thus, the purpose of this study is to suppress an initial drift and to search for new easy polymer to possess more performance of sensor responses than conventional matrix membrane such as PVC. In this research, we investigated ISFETs using specific matrix membrane for example, KP-13, Pellethane® and P7281-PU. The initial drift was evaluated from the fluctuation of the response values generated by ISFETs which are immersed in saliva or aqueous solution. As a result, P7281-PU showed its suppression effect for the initial drift in the whole saliva and various solutions. Furthermore, the cause of drift may be H+ diffusion, and drift suppression effect of P7281-PU may be affected by urethane bond capturing H+ in ion-selective membrane. This result suggests a continuous nitrate monitoring and development of wearable sensors.
Mon, 18 February 2019
ARTICLE Download: 74| View: 233| Comments: 0 | doi:10.20944/preprints201902.0157.v1
Subject: Materials Science, Biomaterials Keywords: chitosan hydrogels, silver nanowires, controlled release, antimicrobial activity, bone regeneration
Online: 18 February 2019 (10:38:46 CET)
One-dimensional nanostructures such as silver nanowires (AgNWs) have attracted considerable attention owing to their outstanding electrical, thermal and antimicrobial properties; however, their application in the prevention of infections linked to bone tissue regeneration interventions has not yet been explored. Here we report on the development of an innovative scaffold prepared from chitosan, composite hydroxyapatite and AgNWs (CS-HACS-AgNWs) having both bioactive and antibacterial properties. In vitro results highlighted the antibacterial potential of AgNWs against both gram-positive and gram-negative bacteria. The CS-HACS-AgNWs composite scaffold demonstrated suitable Ca/P deposition, improved gel strength, reduced gelation time, and sustained Ag+ release within therapeutic concentrations. Antibacterial studies showed that the composite formulation was capable of inhibiting bacterial growth in suspension and of completely preventing biofilm formation on the scaffold in the presence of resistant strains. The hydrogels were also shown to be biocompatible, allowing cell proliferation. In summary, the developed CS-HACS-AgNWs composite hydrogels demonstrated significant potential as a scaffold material to be employed in bone regenerative medicine, as it presents enhanced mechanical strength combined with the ability to allow calcium salts deposition, while efficiently decreasing the risk of infections. The results presented justify further investigations into potential clinical applications of these materials.
Mon, 4 February 2019
ARTICLE Download: 102| View: 432| Comments: 0 | doi:10.20944/preprints201902.0034.v1
Subject: Materials Science, Biomaterials Keywords: nasal permeability; nose-to-brain; simvastatin; nanocapsules; mucoadhesion; CNS disorders; chitosan
Online: 4 February 2019 (13:27:10 CET)
Drug delivery to the brain represents a challenge especially in the therapy of central nervous system malignancies. Simvastatin (SVT), as other statins, has shown potential anticancer properties that are difficult to exploit in the CNS. In the present work the physico-chemical, mucoadhesive and permeability enhancing properties of simvastatin-loaded poly-ε-caprolactone nanocapsules coated with chitosan for nose-to-brain administration were investigated. Lipid-core nanocapsules coated with different molecular weight (MW) chitosans (LNCchit) prepared by a novel one-pot technique were characterized for particle size, surface charge, particle number density, morphology, drug encapsulation efficiency, interaction between surface nanocapsules with mucin, drug release and permeability across two nasal mucosa models. Results show that all formulations present adequate particle size (below 220 nm), positive surface charge, narrow droplet size distribution (PDI<0.2) and high encapsulation efficiency. Nanocapsules presented controlled drug release and mucoadhesive properties dependent on the MW of the coating chitosan. The results of permeation across RPMI 2650 human nasal cell line evidenced that LNCchit increased the permeation of SVT. In particular, the amount of SVT permeated after 4h for nanocapsules coated with low MW chitosan, high MW chitosan and control SVT was 13.91 ± 0.78 µg, 9.15 ± 1.23 µg and 1.42 ± 0.21 µg respectively. These results were confirmed by the SVT ex vivo permeation across rabbit nasal mucosa. This study highlighted the suitability of LNCchit as promising strategy for the administration of simvastatin for a nose-to-brain approach for the therapy of brain tumors.
Fri, 25 January 2019
ARTICLE Download: 78| View: 469| Comments: 0 | doi:10.20944/preprints201901.0257.v1
Subject: Materials Science, Biomaterials Keywords: Hyper-spectral imaging system; Spectral characteristics; Image processing; Threshold method; Bloodstains recognition
Online: 25 January 2019 (14:54:14 CET)
The identification of bloodstain is one of the most important approaches in obtaining evidence in criminalistics. A threshold method based on spectral co-efficient and interclass variance is proposed in this paper, it is a non-contact, non-destructive method for quickly identifying bloodstains. The spectra of bloodstains and other suspected substances were all extracted from their hyper-spectral image. Then calculate the correlation coefficients of these spectral and interclass variances, analyze the differences between substances. The best blood recognition threshold was determined as 0.9. After preprocessing for eliminating systematic errors, experiments with the threshold 0.9 are carried out to identify bloodstains on the calico and red T-shirt. The method can remarkably identify the bloodstain from other non-blood substances both quickly and efficiently. The blood extraction rate can reach to 93.35% and 89.19%, respectively. It is an important step toward the implementation of bloodstain non-contact and non-destructive identification in forensic casework.
Fri, 4 January 2019
ARTICLE Download: 47| View: 194| Comments: 0 | doi:10.20944/preprints201901.0044.v1
Subject: Materials Science, Biomaterials Keywords: microstructure of liquids; water-salt units; salt microcrystals; hydrated shells; coacervates, self – assembly; air pollution.
Online: 4 January 2019 (14:23:37 CET)
It is shown that structuring at the microlevel is the intrinsic property of water and aqueous solutions. At room conditions water (including "ultrapure" one) and aqueous solutions are dispersed systems in which microcrystals of NaCl, surrounded by a layer of hydrated water (average diameter - 10-15 microns), are "elementary microparticles", which form the basis of the dispersed phase. Possible ways of formation of these microparticles and their evolution in the process of evaporation of unstructured part of water - dispersion medium - are considered. It is shown, in particular, that they are present in the air as aerosol contaminants. When the ionic strength of the solution increases, the water-salt particles coagulate, forming a new phase - coacervates, remaining on the substrate after evaporation of the liquid part of the water. The aggregates of coacervate structures, formed in a liquid medium, are disordered during heating, which can cause a change in a number of physicochemical properties of water at the temperatures of 50°-60°C range that have not been correctly explained in the framework of atomic-molecular concepts.
Fri, 28 December 2018
ARTICLE Download: 138| View: 377| Comments: 0 | doi:10.20944/preprints201812.0329.v1
Subject: Materials Science, Biomaterials Keywords: biomaterials; biofabrication; compartmentalization; materials research; microsystems; nanotechnology; self-assembly; self-organization
Online: 28 December 2018 (04:46:37 CET)
The recommendations of the panel of experts on the further development of the ‘High-Tech Strategy’ of the Government of the Federal Republic of Germany designate the biologization of economic processes along with digitization as the central driver of societal change. Various fields such as the 'biologization of materials research' were then defined in the 'Bio-Agenda' in order to walk the path from biology to innovation. In view of this perspective, we describe how the use of biological materials and mechanisms can lead to resource conservation, the production of intelligent materials and new technological and medical applications. Our strategy, based on research on ‘Biointerfaces in Technology and Medicine’, aims at the development of modular biohybrid systems that could be used as 'biofactories of the future' for sustainable production processes. To achieve this goal, in a first phase already known technologies have to be further refined and integrated in order to obtain and apply compartmentalized reaction systems on different length and time scales. In a second phase, the resulting functional units will be employed to develop dissipative systems useful for biomedical applications and advanced production processes. From a technical point of view, future success in creating 'something entirely new' will depend crucially on robust and complementary research capabilities. Since the close connection of engineering and life sciences at KIT provides an excellent basis for this endeavor, we consider the above perspectives to be feasible.
Mon, 26 November 2018
ARTICLE Download: 65| View: 155| Comments: 0 | doi:10.20944/preprints201811.0585.v1
Subject: Materials Science, Biomaterials Keywords: shape memory nanofiber; shape memory polymer; poly(ε-caprolactone); melting temperature; cell orientation; polyurethane
Online: 26 November 2018 (11:13:07 CET)
This paper reports a rational design of temperature-responsive nanofiber meshes with shape-memory effect. The meshes were fabricated by electrospinning a poly(ε-caprolactone) (PCL)-based polyurethane with different contents of soft and hard segments. The effects of PCL diol/hexamethylene diisocyanate (HDI)/1,4-butanediol (BD) molar ratio in terms of the contents of soft and hard segments on the shape-memory properties were investigated. Although the mechanical property improved with increasing hard segment ratio, optimal shape-memory properties were obtained with a PCL/HDI/BD molar ratio of 1:4:3. At a microscopic level, the original nanofibrous structure was easily deformed into a temporary shape, and recovered its original structure when the sample was reheated. A higher recovery rate (>89%) was achieved even when the mesh was deformed up to 400%. Finally, the nanofiber meshes were used to control the alignment of human mesenchymal stem cells (hMSCs). The hMSCs aligned well along the fiber orientation. The proposed nanofibrous meshes with the shape-memory effect have the potential to serve as in vitro platforms for the investigation of cell functions as well as implantable scaffolds for wound-healing applications.
Tue, 20 November 2018
ARTICLE Download: 52| View: 66| Comments: 0 | doi:10.20944/preprints201811.0482.v1
Subject: Materials Science, Biomaterials Keywords: polycaprolactone; oxygen plasma; Wharton’s Jelly mesenchymal stem cells
Online: 20 November 2018 (05:26:00 CET)
Cell-based therapies and tissue engineering applications require biocompatible substrates that support and regulate the growth, survival, and differentiation of specific cell types. Extensive research efforts in regenerative medicine are devoted to the development of tunable biomaterials which support various cell types including stem cells. In this research, the non-cytotoxic biopolymer polycaprolactone (PCL) was fabricated into 2D and 3D scaffolds with or without the low-pressure oxygen plasma treatment to enhance hydrophilicity. Cellular responses and biocompatibility were evaluated using a human Wharton’s jelly mesenchymal stem cell line (BCP-K1). The 2D PCL scaffolds enhanced initial cell attachment compared to the 3Ds indicated by a higher expression of focal adhesion kinase (FAK). Whilst, the 3D scaffolds promoted cell proliferation and migration as evidenced by higher cyclin A expression and filopodial protrusion, respectively. The 3D scaffolds potentially protected the cell entering to apoptosis/necrosis program and induced cell differentiation, evaluated by gene expression. Both 2D and 3D PCL appeared to have stronger effects on cell behavior than a control substrate (polystyrene). In summarize, the different configuration and surface properties of PCL scaffolds provide various options for modulation of stem cell behaviors, including attachment, proliferation, survival, and differentiation, when combined with specific growth factors and culture conditions.
Mon, 19 November 2018
ARTICLE Download: 60| View: 84| Comments: 0 | doi:10.20944/preprints201811.0450.v1
Subject: Materials Science, Biomaterials Keywords: titanium alloy; silver nanoparticles; surface morphology; mechanical properties; surface free energy; silver ions release
Online: 19 November 2018 (11:00:17 CET)
Dispersed silver nanoparticles (AgNPs) on the surface of titanium alloy (Ti6Al4V) and titanium alloy modified by titania nanotube layer (Ti6Al4V/TNT) substrates were produced by chemical vapor deposition method (CVD) using novel precursor of the formula [Ag5(O2CC2F5)5(H2O)3]. The structure and volatile properties of this compound were determined using single crystal X-ray diffractometry, variable temperature IR spectrophotometry (VT IR), and electron inducted mass spectrometry (EI MS). The morphology and the structure of the produced Ti6Al4V/AgNPs, and Ti6Al4V/TNT/AgNPs composites were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Moreover, measurements of hardness, Young’s modulus, adhesion, and surface free energy have been carried out. The ability to release silver ions from the surface of produced nanocomposite materials immersed in PBS solution has been estimated using inductively coupled plasma mass spectrometry (ICP MS). The wettability and the surface free energy of samples were estimated on the base of contact angle studies with the use of water and diiodomethane. Among the studied surface-modified titanium alloy implants, the best nano-mechanical properties were noticed for the Ti6Al4V/TNT15/AgNPs composite. The location of silver nanoparticles inside of titania nanotubes caused their lowest release rate, which may indicate on suitable properties above mentioned type of the composite for the construction of implants with a long term of antimicrobial activity.
Wed, 7 November 2018
ARTICLE Download: 97| View: 66| Comments: 0 | doi:10.20944/preprints201811.0155.v1
Subject: Materials Science, Biomaterials Keywords: discrete dipole approximation (DDA); up-conversion nanoparticles (UCNP); lanthanide-gold
Online: 7 November 2018 (09:34:20 CET)
Up-conversion nanoparticles (UCNP) under near-infrared (NIR) light irradiation have been well investigated in the field of bio-imaging. However, the low up-conversion luminescence (UCL) intensity limits applications. Plasmatic modulation has been proposed as an effective tool to adjust the luminescence intensity and lifetime. In this study discrete dipole approximation (DDA) was explored concerning guiding the design of [email protected] structures with enhanced UCL intensity. The extinction effects of gold shells could be changed by adjusting the distance between the UCNPs and the Au NPs by synthesized tunable mesoporous silica (mSiO2) spacers. Enhanced UCL was obtained under 808 nm irradiation. Theoretical predictions could not be demonstrated to full extend by experimental data, indicating that better models for simulation need to better take into account inhomogeneities in particle morphologies.
Mon, 29 October 2018
ARTICLE Download: 50| View: 92| Comments: 0 | doi:10.20944/preprints201810.0680.v1
Subject: Materials Science, Biomaterials Keywords: desensitizing paste; dentin; retention; cements; cobalt-chromium
Online: 29 October 2018 (11:50:02 CET)
The effect of dentin pretreatment with desensitizing paste containing 8% arginine and calcium carbonate on the retention of laser-sintered cobalt-chromium (Co-Cr)-based crowns was examined. Forty molars were prepared using a standardized protocol. The Co-Cr crowns were produced using selective laser melting. The teeth were either pretreated with the desensitizing paste or not pretreated. After one week, each group was cemented with glass ionomer cement (GIC) or zinc phosphate cement (ZPC). Surface areas of the teeth were measured before cementation. After aging, the cemented crown-tooth assemblies were tested for retentive strength using a universal testing machine. The debonded surfaces of the teeth and crowns were examined at 2.7× magnification. Pretreating the dentin surfaces with the desensitizing paste before cementation with GIC or ZPC did not affect the retention of the Co-Cr crowns. The retention of the GIC group (6.04±1.10 MPa) was significantly higher than that of the ZPC group (2.75±1.25 MPa). The predominant failure mode for the ZPC and for the nontreated group of the GIC was adhesive cement-dentin; for the GIC-treated group, it was adhesive cement-crown. The desensitizing paste can be safely used to reduce postcementation sensitivity without reducing the retentive strength of Co-Cr crowns cemented with GIC or ZPC.
Thu, 25 October 2018
ARTICLE Download: 76| View: 146| Comments: 0 | doi:10.20944/preprints201810.0598.v1
Subject: Materials Science, Biomaterials Keywords: nano-structures; polymer-matrix composites (PMCs); mechanical properties; thermal properties
Online: 25 October 2018 (06:20:41 CEST)
Poly(vinylidene fluoride) nanocomposites processed with different morphologies, such as porous and non-porous films and fibres, have been prepared with silica nanoparticles (SiNPs) of varying diameter (17, 100, 160 and 300 nm) which in turn have encapsulated perylenediimide (PDI), a fluorescent molecule. Structural, morphological, optical, thermal, and mechanical properties of the nanocomposites, with SiNP filler concentration up to 16 wt% were evaluated. Further, cytotoxicity and cell proliferation studies were performed. All SiNPs are negatively charged independently of the pH and more stable from pH 5 upwards. The SiNPs introduction within the polymer matrix increases the contact angle independently of the nanoparticle diameters and the smallest ones (17 nm) improve the PVDF Young modulus from 0.94 ± 0.04 GPa for the pristine polymer film to 1.05 ± 0.06 GPa. Varying filler diameter, physico-chemical, thermal and mechanical properties of the polymer matrix were not significantly affected. Finally, the SiNPs inclusion does not induce cytotoxicity in murine myoblasts (C2C12) after 72 h of contact and proliferation studies reveal that the prepared composites represent a suitable platform for tissue engineering applications, as they allow to combine the biocompatibility and piezoelectricity of the polymer with the possible functionalization and drug encapsulation and release of the SiNP.
Tue, 9 October 2018
ARTICLE Download: 78| View: 167| Comments: 0 | doi:10.20944/preprints201810.0170.v1
Subject: Materials Science, Biomaterials Keywords: antibacterial; biofilm; caries; dental composite; quaternary ammonium monomers; human in situ study
Online: 9 October 2018 (04:43:45 CEST)
Cariogenic oral biofilms cause a considerable amount of recurrent dental caries around composite restorations every year, resulting in unprosperous oral health status and expensive restorative treatment for many patients. Quaternary ammonium monomers that can be copolymerized with the current dental resin systems have been increasingly explored for modulation of dental plaque biofilm growth over dental composite surfaces. Here, we investigated the effect of bis(2-methacryloyloxyethyl) dimethylammonium bromide (QADM), against human overlying mature oral biofilms grown intra-orally in human participants for 7 and 14 days, for the first time. Seventeen volunteers wore palatal devices containing composite specimens containing 10% by mass of QADM or a control composite without QADM. After 7 and 14 days, the adherent biofilms were collected for determination of bacterial counts via colony-forming unit (CFU) counts. The biofilm viability, chronological changes, and percentage coverage were also determined by live/dead staining. QADM composites caused a significant inhibition of S. mutans biofilm formation for up to seven days. No difference in the CFU values were found for the 14-day period. Our findings suggest that (1) QADM composite was successful in inhibiting 1-3 day biofilms in the oral environment in vivo; (2) QADM significantly reduced the portion of S.mutans group in a time course where patients at high risk of caries would develop initial enamel carious lesions; and (3) stronger antibiofilm activity is required for the control of mature long-term cariogenic biofilms. These results provide a perspective on the value of integrating bioactive restorative materials with traditional caries management approaches into clinical practice. Contact-killing strategies via dental materials aiming to prevent or at least reduce high numbers of cariogenic bacteria seem to be a promising approach in patients at high risk of recurrence of dental caries around composites.
Thu, 4 October 2018
ARTICLE Download: 75| View: 219| Comments: 0 | doi:10.20944/preprints201810.0088.v1
Subject: Materials Science, Biomaterials Keywords: There are many molecules used as drug carrier. TUD-1 is a newly synthesized mesoporous silica (SM) molecule possess two important features; consists of mesoporous so it is very suitable to be drug carrier in addition to that it has the ability to induce apoptosis in cancer cells. However, the effect of TUD-1 appears to act as cell death inducer, regardless of whether it is necrosis or apoptosis. Unfortunately, recent studies indicate that a proportion of cells undergo necrosis rather than apoptosis, which limits the use of TUD-1 as a secure treatment. On the other hand, lithium considered as necrosis inhibitor element. Hence, current study based on the idea of production a new Li/TUD-1 by incorporated mesoporous silica (TUD-1 type) with lithium in order to produce a new compound that has the ability to activate apoptosis by mesoporous silica (TUD-1 type) and at the same time can inhibit the activity of necrosis by lithium. Herein, lithium was incorporated in TUD-1 mesoporous silica by
Online: 4 October 2018 (15:54:02 CEST)
There are many molecules used as drug carrier. TUD-1 is a newly synthesized mesoporous silica (SM) molecule possess two important features; consists of mesoporous so it is very suitable to be drug carrier in addition to that it has the ability to induce apoptosis in cancer cells. However, the effect of TUD-1 appears to act as cell death inducer, regardless of whether it is necrosis or apoptosis. Unfortunately, recent studies indicate that a proportion of cells undergo necrosis rather than apoptosis, which limits the use of TUD-1 as a secure treatment. On the other hand, lithium considered as necrosis inhibitor element. Hence, current study based on the idea of production a new Li/TUD-1 by incorporated mesoporous silica (TUD-1 type) with lithium in order to produce a new compound that has the ability to activate apoptosis by mesoporous silica (TUD-1 type) and at the same time can inhibit the activity of necrosis by lithium. Herein, lithium was incorporated in TUD-1 mesoporous silica by using sol-gel technique in one step synthesis procedure. Moreover, lithium was incorporated in TUD-1 with different loading in order to form different active sites such as isolated lithium ions, nanoparticles of Li2O, and bulky crystals of Li2O. The ability of the new compounds to induce apoptosis and prevent necrosis was evaluated on three different types of cancer cell lines which are; liver HepG-2, Breast MCF-7 and colon HCT116. The obtained results show that Li/TUD-1has the ability to control necrosis and thus reduce the side effects of treatments containing silica in the case of lithium has been added to them, especially in chronic cases. This has been demonstrated by the significant increase in the IC50 value and cell viability comparing to control groups. Consequently, the idea is new, so it definitely needs more develop and test with materials that have more apoptotic impact than silica in order to induce apoptosis without induction of necrosis.
Fri, 7 September 2018
ARTICLE Download: 251| View: 147| Comments: 0 | doi:10.20944/preprints201809.0138.v1
Subject: Materials Science, Biomaterials Keywords: Gadolinium oxide, mesoporous, silica, biocompatible, zeta potential, luminescence properties
Online: 7 September 2018 (13:22:19 CEST)
Highly colloidal Eu-doped Gd2O3 nanoparticles(core-NPs) were synthesized by thermal decomposition via weak base at low temperature (150oC), subsequently, silica layers were deposited to increased colloidal stability, solubility, biocompatibility and no-toxicity at the environmental condition. XRD results indicate the highly purified, crystalline, single phase cubic phase Gd2O3 nanocrystals. TEM image shows the mesoporous thick silica layer was effectively coated over the core nanocrystals, which have irregular size with nearly spherical shape and a mean grain size is about 10-30 nm. Absorption spectra and zeta potential results in aqueous media revealed that solubility, colloidal stability, and biocompatibility character was enhanced from core to core-shell structure because of silica layer surface encapsulation. The samples demonstrate excellent photoluminescence properties (dominant emission 5D0→7F2 transition in red region at 610 nm) indicated the advantage to use in optical bio-detection and bio-labeling etc. The photoluminescence intensity of the silica shell modified core/shell nanoparticles were suppressed relatively core-nanoparticles, it indicates the multi-photon relaxation pathways arising from the surface coated high vibrational energy molecules of the silanol groups. The core/nSiO2/mSiO2 nanocrystals display strong emission (5D0→7F2) transition along with excellent solubility and biocompatibility, which may find promising applications in photonic based biomedical applications.
Mon, 3 September 2018
REVIEW Download: 176| View: 265| Comments: 0 | doi:10.20944/preprints201809.0047.v1
Subject: Materials Science, Biomaterials Keywords: Graphene oxide; Stem cells; Growth; Cell differentiation; Biomaterials
Online: 3 September 2018 (15:44:08 CEST)
Stem cells are undifferentiated cells which can give rise to any types of cells in our body. Hence, they have been utilized for various applications such as drug testing and disease modeling. However, for the successful of those applications, the survival and differentiation of stem cells into specialized lineages should be well controlled. Growth factors and chemical agents are the most common signals to promote the proliferation and differentiation of stem cells. However, those approaches holds several drawbacks such as the negative side effects, degradation or denaturation, and expensive. To address such limitations, nanomaterials have been recently used as a better approach for controlling stem cells behaviors. Graphene oxide is the derivative of graphene, the first 2D materials in the world. Recently, due to its extraordinary properties and great biological effects on stem cells, many scientists around the world have utilized graphene oxide to enhance the differentiation potential of stem cells. In this mini review, we highlight the key advances about the effects of graphene oxide on controlling stem cell growth and various types of stem cell differentiation. We also discuss the possible molecular mechanisms of graphene oxide in controlling stem cell growth and differentiation.
Thu, 30 August 2018
ARTICLE Download: 100| View: 162| Comments: 0 | doi:10.20944/preprints201808.0527.v1
Subject: Materials Science, Biomaterials Keywords: emdogain; amelogenin; odontoblast; differentiation; mineralization
Online: 30 August 2018 (13:01:52 CEST)
Enamel matrix derivative (EMD) is used for periodontal tissue regeneration therapy. We designed a synthetic amelogenin peptide (SP) derived from EMD, and have previously investigated the biological function of SP. However, it is unknown whether SP affects odontoblastic differentiation. In the present study, we investigated the effects of SP in odontoblast-like cells, KN-3 cells. KN-3 cells were treated with SP (0, 1, 10, 100, or 1000 ng/mL) and then cultured for 3, 8, 24, or 48 hours, in order to determine the effects of SP on cell proliferation and detect its optimum concentration. To investigate the effect of SP on odontogenic differentiation, KN-3 cells were treated with SP in odontogenic differentiation medium cultured for 3 or 7 days. Odontogenic differentiation was performed by measuring alkaline phosphatase (ALP) activity, the mRNA expression of dentin sialophosphoprotein (DSPP), the formation of calcified nodules, and calcium deposition into the extracellular matrix. The addition of SP significantly promoted KN-3 cell proliferation; a concentration of 100 ng/ml generated the greatest change in cell proliferation. SP also showed increased expression of markers of odontogenic differentiation and mineralization. These results suggest that SP, derived from EMD, could be a potential for applicate to the dental pulp capping.
Tue, 21 August 2018
ARTICLE Download: 127| View: 143| Comments: 0 | doi:10.20944/preprints201808.0386.v1
Subject: Materials Science, Biomaterials Keywords: anti-demineralization; antibacterial effect; white spot lesion; graphene oxide; bioactive glass
Online: 21 August 2018 (16:24:58 CEST)
White spot lesions (WSLs), a side effect of orthodontic treatment, can result in reversible and unaesthetic results. Graphene oxide (GO) with a bioactive glass (BAG) mixture([email protected]) was added to Low Viscosity Transbond XT(LV) in a ratio of 1, 3, 5%. The composite’s characterization and its physical and biological properties were verified with scanning electron microscopy(SEM) and X-ray diffraction(XRD); its microhardness, shear bond stress (SBS), cell viability, and adhesive remnant index (ARI) were also assessed. Efficiency in reducing WSL was evaluated using antibacterial activity of S. mutans. Anti-demineralization was analyzed using a cycle of the acid-base solution. Adhesives with 3 or 5 wt.% of [email protected] showed significant increase in microhardness compared with LV. The sample and LV groups showed no significant differences in SBS or ARI. The cell viability test confirmed that none of the sample groups showed higher toxicity compared to the LV group. Antibacterial activity was higher in the 48-hour group than in the 24-hour group; the 48-hour test showed that [email protected] had a high antibacterial effect, which was more pronounced in 5 wt.% of [email protected] Anti-demineralization effect was higher in the [email protected] than in the LV-group; the higher the [email protected] concentration, the higher the anti-demineralization effect.
Wed, 15 August 2018
REVIEW Download: 433| View: 213| Comments: 0 | doi:10.20944/preprints201808.0280.v1
Subject: Materials Science, Biomaterials Keywords: conductive hydrogel; tissue engineering; biomaterials; physical and electrical properties
Online: 15 August 2018 (16:12:51 CEST)
In the field of tissue engineering, conductive hydrogels have been the most effective biomaterials to mimic the biological and electrical properties of tissues in the human body. The main advantages of conductive hydrogel include not only its physical properties, but also its adequate electrical properties, thus providing electrical signals to cells efficiently. However, when introducing a conductive material into a non-conductive hydrogel, a conflicting relationship between the electrical and mechanical properties may develop. This review examines the strengths and weaknesses of the generation of conductive hydrogels using various conductive materials and introduces the use of these conductive hydrogels in tissue engineering applications.
Tue, 14 August 2018
ARTICLE Download: 285| View: 261| Comments: 0 | doi:10.20944/preprints201808.0253.v1
Subject: Materials Science, Biomaterials Keywords: graphene; silver nanoparticles; PHA; electrospun biomaterial; antibacterial
Online: 14 August 2018 (14:16:21 CEST)
Many wounds are unresponsive to current available treatment techniques and therefore there is an immense need to explore suitable materials including biomaterials, which are being considered as the crucial factor to accelerate the healing cascade. In this study, we fabricated polyhydroxyalkanoate based antibacterial mats via electrospun technique. One-pot green synthesized graphene decorated silver nanoparticles (GAg) were incorporated into the fibres of poly-3 hydroxybutarate-co-12 mol% hydroxyhexanoate (P3HB-co-12mol% HHx), a co-polymer of polyhydroxyalkanoate (PHA) family which is highly biocompatible, biodegradable and flexible in nature. The synthesised PHA/GAg biomaterial was characterized by field emission scanning electron microscopy (FESEM), elemental mapping, thermogravimetric analysis (TGA), UV-visible spectroscopy (UV-vis) and Fourier transform infrared spectroscopy (FTIR). In-vitro antibacterial analysis were performed to investigate the efficacy of PHA/GAg against gram positive Staphylococcus aureus (S.aureus) strain 12600 ATCC and gram negative Escherichia coli (E.coli) strain 8739 ATCC. The results indicated that the PHA/GAg demonstrated significant reduction of Staphylococcus aureus (S.aureus strain 12600 ATCC) and Escherichia coli (E.coli strain 8739 ATCC) as compared to bare PHA or PHA-rGO in 2 hours of time. The P value (P< 0.05) was obtained by using 2 sample T-test distribution.
Mon, 13 August 2018
ARTICLE Download: 148| View: 117| Comments: 0 | doi:10.20944/preprints201808.0228.v1
Subject: Materials Science, Biomaterials Keywords: Cloth thermal comfort; Heat transfer between body, cloth and ambience; Changing sign of temperature gradient; Body sweating and phase change; Non-affinity between the behaviors of cloth and fibers
Online: 13 August 2018 (11:44:47 CEST)
Cloth wearing seems so natural that everyone is self-deemed knowledgeable and has some expert opinions about it. However to clearly explain the physics involved, and hence to make predictions for clothing design or selection, turns out as demonstrated below to be quite challenging even for experts. Cloth is a multiphased, porous and anisotropic material system and usually in multilayers. Unlike ordinary engineering heat transfer problems, the human body acts as an internal heat source in a clothing situation, thus forming a temperature gradient between body and ambient, and the sign of this gradient often changes as the ambient temperature varies. Our body also perspires and the sweat evaporates, an effective body cooling process via phase change. To bring all the variables into analysis quickly escalates into a formidable task. This work attempts to unravel the problem from a physics perspective, focusing on several rarely noticed yet critically important mechanisms involved so as to offer a clear and accurate depiction of the principles in clothing thermal comfort.
Tue, 7 August 2018
ARTICLE Download: 1631| View: 491| Comments: 0 | doi:10.20944/preprints201808.0145.v1
Subject: Materials Science, Biomaterials Keywords: secondary lithium ion battery; all-solid-state battery; solid polymer electrolyte; succinonitrile (SN); lithium(trifluoromethanesulfonyl)imide (LiTFSI)
Online: 7 August 2018 (13:18:20 CEST)
Considering the safety issues of Li ion batteries, all-solid-state polymer electrolyte has been one of the promising solutions. In this point, achieving a Li ion conductivity in the solid state electrolytes comparable to liquid electrolytes (>1 mS/cm) is particularly challenging. Employment of polyethylene oxide (PEO) solid electrolyte has not been not enough in this point due to high crystallinity. In this study, hybrid solid electrolyte (HSE) systems are designed with Li1.3Al0.3Ti0.7(PO4)3(LATP), PEO and Lithium hexafluorophosphate (LiPF6) or Lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). Hybrid solid cathode (HSC) is also designed using LATP, PEO and lithium cobalt oxide (LiCoO2, LCO)—lithium manganese oxide (LiMn2O4, LMO). The designed HSE system displays 3.0 × 10−4 S/cm (55 ℃) and 1.8 × 10−3 S/cm (23 ℃) with an electrochemical stability as of 6.0 V without any separation layer introduction. Li metal (anode)/HSE/HSC cell in this study displays initial charge capacity as of 123.4/102.7 mAh/g (55 ℃) and 73/57 mAh/g (25 °C). To these systems, Succinonitrile (SN) has been incorporated as a plasticizer for practical secondary Li ion battery system development to enhance ionic conductivity. The incorporated SN effectively increases the ionic conductivity without any leakage and short-circuits even under broken cell condition. The developed system also overcomes the typical disadvantages of internal resistance induced by Ti ion reduction. In this study, optimized ionic conductivity and low internal resistance inside the Li ion battery cell have been obtained, which suggests a new possibility in the secondary Li ion battery development.
Tue, 31 July 2018
ARTICLE Download: 163| View: 221| Comments: 0 | doi:10.20944/preprints201807.0611.v1
Subject: Materials Science, Biomaterials Keywords: hydrogels; cardiac patches; 3D bioprinting; furfuryl-gelatin; lattice
Online: 31 July 2018 (08:06:27 CEST)
3D bioprinting holds great promise in the field of regenerative medicine as it can create complex structures in a layer-by-layer manner using cell-laden bioinks, making it possible to imitate native tissues. Current bioinks lack both the high printability and the biocompatibility required in this respect. Hence, the development of bioinks that are capable of both properties is needed. In our previous study, a furfuryl-gelatin based bioink, crosslinkable by visible light, was used for creating mouse mesenchymal stem cell-laden structures with high fidelity. In this study, lattice mesh geometries were printed in a comparative study to test against the properties of a traditional rectangular-sheet. After 3D printing and crosslinking, both structures were analysed for swelling and rheological properties, and their porosity estimated using scanning electron microscopy. Results showed that the lattice structure was relatively more porous but sturdy and exhibited a lower degradation rate compared to the rectangular-sheet. Further, the lattice allowed encapsulation of a greater number of cells, allowing them to proliferate to a greater extent compared to the rectangular-sheet that retained a lesser number of cells initially. All of these results collectively affirmed that the lattice poses as a superior scaffold design for tissue engineering applications.
Thu, 26 July 2018
ARTICLE Download: 154| View: 179| Comments: 0 | doi:10.20944/preprints201807.0521.v1
Subject: Materials Science, Biomaterials Keywords: photobioreactor; Rhodopseudomonas sp. S16-VOGS3; poly-3-hydroxybutyrate; thermal analysis; C/N ratio
Online: 26 July 2018 (15:56:26 CEST)
In the present study, the performance of a 70 L photobioreactor, operating outdoors, was investigated using a purple bacterial strain as Rhodopseudomonas sp. S16-VOGS3 for producing poly-3-hydroxybutyrate (PHB). The novel photobioreactor was equipped with 5L-shaped rows; the bottom of every row was placed in a stainless-steel tank containing water with controlled temperature. The photofermentation trials were carried out under fed-batch mode and under a semi-continuous regimen using lactic acid as carbon source. The effect of the irradiance and the C/N ratio on the PHB accumulation was investigated, in order to evaluate the optimal bacterial growth. The results showed the feasibility of the prototype photobioreactor for the production of PHB by Rhodopseudomonas sp. S16-VOGS3 under the natural light/dark cycle. During the fed-batch growth (144 h long), the cumulative PHB increased quickly reaching the maximum value of 377 mg/L and decreased to 255 mg/L during the semi-continuous regimen (336 h long).
Wed, 25 July 2018
ARTICLE Download: 162| View: 172| Comments: 0 | doi:10.20944/preprints201807.0464.v1
Subject: Materials Science, Biomaterials Keywords: corrosion; plastic deformation; titanium; titanium alloys; surface treatment
Online: 25 July 2018 (04:14:36 CEST)
1) Background: The objective was to evaluate the corrosion resistance of different commercially pure ultrafine-grained (UFG) titanium and its alloys with acid etched surface processed by equal-channel angular pressing (ECAP); 2) Methods: Coarse-grained and UFG titanium samples were investigated using polarization resistance technique. Surface characteristics of the native oxidized layer were evaluated by TEM and XRD. Electrochemical tests were under physiological electrolyte at a rate of 1 and 10 mV/s. Weight loss tests were performed after immersion into HCl solution for up to 3 years; 3) Results: UFG titanium was less susceptible to corrosion which was identified under lower rates and at higher polarization resistance than its coarse grain counterparts. Titanium Grade 2 and Grade 4 demonstrated similar corrosion susceptibility. Titanium Grade 5 revealed a thin and tightly adhered native oxide layer with adequate corrosion resistance; 4) Conclusions: ECAP process imposed a more compact and adhered oxidized layer. Surface etching techniques delivered a thicker native TiO2 layer, being both grain refinement and surface etching techniques responsible for the improved corrosion resistance of Titanium samples under physiological environment after 3 years of observation.
Tue, 24 July 2018
ARTICLE Download: 173| View: 184| Comments: 0 | doi:10.20944/preprints201807.0459.v1
Subject: Materials Science, Biomaterials Keywords: Superparamagnetic iron oxide; Magnetic resonance imaging; Solid lipid nanoparticles; Galactose; Liver-targeted
Online: 24 July 2018 (14:01:51 CEST)
The aim of this study was to develop a novel nanostructured lipid carriers (NLCs) with hepatocytes targeting as carriers for the magnetic resonance imaging (MRI) contrast agent (i.e., magnetic nanostructured lipid carriers, MNLCs), and to evaluate the targeting ability of the MNLCs with T2-weighted MRI both in vitro and in vivo. Here, the galactose-octadecylamine (Gal-ODA) conjugates were synthesized by chemical coupling reaction between lactose acid (LA) and octadecylamine (ODA). Then the superparamagnetic iron oxide (SPIO) loaded nanostructured lipid carrier (conjugated by Gal-ODA, Gal-NLC-SPIO) was prepared by emulsification-ultrasonic method using monoglyceride as lipid materials. The Gal-NLC-SPIO with a diameter of about 50 nm could specifically internalize into LO2 (human hepatic cell line) cells. In vitro MRI results also proved the specific targeting ability of Gal-NLC-SPIO to LO2 cells. The in vivo MR imaging experiments using an orthotopic intrahepatic xenograft tumor model further validated the hepatocytes targeted effect of Gal-NLC-SPIO. The results of this study suggested that Gal-NLC-SPIO can be used as a contrast agent to aid in the diagnosis of hepatic diseases.
Tue, 17 July 2018
ARTICLE Download: 297| View: 211| Comments: 0 | doi:10.20944/preprints201807.0314.v1
Subject: Materials Science, Biomaterials Keywords: empty fruit bunch, cellulose, palm oil industry, acetylation, silylation
Online: 17 July 2018 (16:05:28 CEST)
Increase demand for palm oil production has indirectly increased waste and pollution. Empty fruit bunch (EFB), which is the major solid waste from this industry, has the potential to be further treated into valuable product. In this study, cellulose will be extracted from EFB through alkali treatment and acid hydrolysis treatment with a different approach and further modified via acetylation and silylation technique. The modified samples are to be utilized to reduce pollution due to palm oil mill effluent (POME) and carbon dioxide (CO2) emission from the industry. The characterization of the extracted and modified cellulose was carried out using attenuated total reflectance-Fourier transform infrared (ATR-FTIR), thermogravimetric analysis (TGA) and scanning electron microscope (SEM). ATR-FTIR analysis revealed that the cellulose was successfully extracted from raw EFB and the cellulose-acetyl, nanocrystalline cellulose (NCC) and cellulose-2 has been successfully modified from the cellulose. TGA analysis shows that both modified cellulose have higher thermal stability compared to raw EFB and extracted cellulose. SEM morphology of the modified cellulose shows a higher surface area due to the wrinkled formation while the wax layer and cuticle pore has been diminished clearly. The modified sample gave a significant performance where cellulose-acetyl absorbed 98.5% of oil compared to unmodified cellulose-1 sample that only absorbed 5% of oil from POME. NCC-AEAPDMS adsorbed physically and chemically 3.5 cm3/g CO2 gas compared to NCC sample, which undergoes only physical adsorption with maximum capacity up to 2.4 cm3/g. Thus, modification can enhanced the performance of cellulose for industrial applications.
Mon, 16 July 2018
ARTICLE Download: 208| View: 171| Comments: 0 | doi:10.20944/preprints201807.0288.v1
Subject: Materials Science, Biomaterials Keywords: calcium phosphate cement; methylcellulose; 3D plotting; support; hydroxyapatite
Online: 16 July 2018 (12:55:42 CEST)
3D plotting is an additive manufacturing technology enabling biofabrication, thus the integration of cells or biologically sensitive proteins or growth factors into the manufacturing process. However, most (bio-)inks developed for 3D plotting were not shown to be processed into clinical relevant geometries comprising critical overhangs and cavities, which would collapse without a sufficient support material. Herein, we have developed a support hydrogel ink based on methylcellulose (mc), which is able to act as support as long as the co-plotted main structure is not stable. Therefore, 6 w/v %, 8 w/v % and 10 w/v % mc were allowed to swell in water, resulting in viscous inks, which were characterized for their rheological and extrusion properties. The successful usage of 10 w/v % mc as support ink was proven by multichannel plotting of the support together with a plottable calcium phosphate cement (CPC) acting as main structure. CPC scaffolds displaying critical overhangs or a large central cavity could be plotted accurately with the newly developed mc support ink. The dissolution properties of mc allowed complete removal of the gel without residuals, once CPC setting was finished. Finally, we fabricated a scaphoid bone model by computed tomography data acquisition and co-extrusion of CPC and the mc support hydrogel.
ARTICLE Download: 167| View: 192| Comments: 0 | doi:10.20944/preprints201807.0286.v1
Subject: Materials Science, Biomaterials Keywords: heat-induced; wood discoloration; Eucalyptus; lignin; chromophore system.
Online: 16 July 2018 (12:45:03 CEST)
The color changes corresponding to chromophore structures in lignin caused by exposure of Eucalyptus（Eucalyptus grandis and E. urophylla）to heat were investigated. Eucalyptus wood samples were heated in saturated steam atmospheres for 10 h at 110℃, 130℃, and 150℃. The lignin was isolated before and after heat treatment. The physicochemical properties of the lignin and changes in chromophore structures during heat treatment was evaluated through wet chemical analysis, FTIR, UV-Vis, GPC, XPSand 13C-NMR. The color of the wood became darker and redder with the increase in pressure and temperature. Depolymerization and dehydration reactions occurred via demethoxylation with heat treatment in saturated steam at 110℃ or 130℃. Lignin condensed to form insoluble compounds after heat treatment in saturated steam at 150℃. G units increased and S units decreased through demethylation during heat treatment, as revealed by FTIR and 13C-NMR analysis.
Fri, 13 July 2018
REVIEW Download: 413| View: 220| Comments: 0 | doi:10.20944/preprints201807.0241.v1
Subject: Materials Science, Biomaterials Keywords: biomaterial; bone regeneration; drug release; hydrogel; lignin; multivariate data processing; osteogenesis; scaffolds; stem cells; tissue engineering
Online: 13 July 2018 (15:07:37 CEST)
Renewable resources gain increasing interest as source for environmentally benign biomaterials, such as drug encapsulation/release compounds, and scaffolds for tissue engineering in regenerative medicine. Being the second largest naturally abundant polymer, the interest in lignin valorization for biomedical utilization is rapidly growing. Depending on resource and isolation procedure, lignin shows specific antioxidant and antimicrobial activity. Today, efforts in research and industry are directed toward lignin utilization as renewable macromolecular building block for the preparation of polymeric drug encapsulation and scaffold materials. Within the last five years, remarkable progress has been made in isolation, functionalization and modification of lignin and lignin-derived compounds. However, literature so far mainly focuses lignin-derived fuels, lubricants and resins. The purpose of this review is to summarize the current state of the art and to highlight the most important results in the field of lignin-based materials for potential use in biomedicine (reported in 2014–2018). Special focus is drawn on lignin-derived nanomaterials for drug encapsulation and release as well as lignin hybrid materials used as scaffolds for guided bone regeneration in stem cell-based therapies.
Fri, 6 July 2018
ARTICLE Download: 194| View: 233| Comments: 0 | doi:10.20944/preprints201807.0114.v1
Subject: Materials Science, Biomaterials Keywords: biomass; briquette; combustion; density; energy source
Online: 6 July 2018 (09:48:02 CEST)
This study investigated the physical and combustion properties of briquettes produced from agricultural wastes (groundnut shells and corn cobs), wood residues (Anogeissus leiocarpus) and admixtures of the particles at 15%, 20% and 25% starch levels (binder). A 6 x 3 factorial experiments in a Completely Randomized Design (CRD) was adopted for the study. The briquettes produced were analyzed for density, volatile matter, ash content, fixed carbon and specific heat of combustion. The result revealed that the density ranged from 0.44g/cm3 to 0.53g/cm3, while briquettes produced from groundnut shells had the highest (0.53g/cm3) significant mean density. Mean volatile matter and ash content of the briquettes ranged from 24.35% to 34.95% and 3.37% to 4.91%. A. leiocarpus and corn cobs particles had the lowest and highest ash content respectively. The briquette fixed carbon and specific heat of combustion ranged from 61.68% to 68.97% and 7362kca/kg to 8222kca/kg respectively. Briquette produced from A. leiocarpus particles had the highest specific heat of combustion. In general, briquettes produced from A. leiocarpus particles and admixture of groundnut shell and A. leiocarpus particles at 25% starch level had better quality in terms of density and combustion properties and thus suitable as environmentally friendly alternative energy source.
Wed, 4 July 2018
ARTICLE Download: 149| View: 234| Comments: 0 | doi:10.20944/preprints201807.0079.v1
Subject: Materials Science, Biomaterials Keywords: PLA fibers, organosulfur compounds, garlic extracts, mesenchymal stem cells, microstructure, thermal and mechanical properties, cytotoxicity, antibacterial properties.
Online: 4 July 2018 (16:19:17 CEST)
The design of biomaterial platforms able to release bioactive molecules is mandatory in tissue repair and regenerative medicine. In this context, electrospinning is a user-friendly, versatile and low-cost technique, able to process different kinds of materials in micro- and nano-fibers with a large surface area-to-volume ratio for an optimal release of gaseous signalling molecules. Recently, the antioxidant and anti-inflammatory properties of the endogenous gasotramsmitter hydrogen sulfide (H2S), as well as its ability to stimulate relevant biochemical processes on the growth of mesenchymal stem cells (MSC), have been investigated. Therefore, in this work, new poly(lactic) acid fibrous membranes (PFM), doped and functionalized with H2S slow-releasing donors extracted from garlic, were synthetized. These innovative H2S-releasing mats were characterized for their morphological, thermal, mechanical and biological properties. Their antimicrobial activity and effects on the in vitro human cardiac MSC growth, either in the presence or in the absence of oxidative stress, were here assessed. On the basis of the results here presented, these new H2S-releasing PFM could represent promising and low-cost scaffolds or patches for biomedical applications in tissue repair.
Tue, 3 July 2018
ARTICLE Download: 195| View: 194| Comments: 0 | doi:10.20944/preprints201807.0021.v1
Subject: Materials Science, Biomaterials Keywords: biomaterials; cobalt ferrites; poly(hydroxybutyrate-co-hydroxyvalerate); tissue engineering
Online: 3 July 2018 (05:12:53 CEST)
Polymer-based piezoelectric biomaterials have already proven their relevance for tissue engineering applications. Further, the morphology of the scaffolds plays also an important role in cell proliferation and differentiation. The present work reports on poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV), a biocompatible, biodegradable and piezoelectric biopolymer that has been processed in different morphologies, including films, fibres, microspheres and 3D scaffolds. Further, the corresponding magnetically active PHBV-based composites were also produced. The effect of the morphology on physico-chemical, thermal, magnetic and mechanical properties of pristine and composites samples was evaluated, as well as their cytotoxicity. It was observed that the morphology does not strongly affect the properties of the pristine samples but the introduction of cobalt ferrites induces changes in the degree of crystallinity that could affect the applicability of prepared biomaterials. Young modulus is dependent of the morphology and also increases with the addition of cobalt ferrites. Both, pristine and PHBV/cobalt ferrite composite samples are no cytotoxic, indicating their suitability for tissue engineering applications.
Mon, 2 July 2018
ARTICLE Download: 168| View: 232| Comments: 0 | doi:10.20944/preprints201807.0003.v1
Subject: Materials Science, Biomaterials Keywords: aerogel; biopolymer; pectin; alginate; chitosan; beads; jet cutting
Online: 2 July 2018 (08:06:51 CEST)
The aim of this work is to develop a method to produce spherical biopolymer-based aerogel particles, which is capable for scale up in the future. Therefore, jet cutting method is suggested. Amidated pectin and sodium alginate were used as precursor (1–3 wt. % solution) for particle production via jet cutting. Gelation was realized via two methods: internal setting method (using calcium carbonate particles as cross-linker and citric and acidic acid for pH adjustment) and diffusion method (in calcium chloride solutions). Gel particles were subjected to solvent exchange to ethanol and consequent supercritical drying with CO2. Spherical aerogel particles with narrow particle size distribution in the range of 400 to 1500 µm and with specific surface area of around 500 m2/g could be produced. Overall, it can be concluded that jet cutting method is suitable for aerogel particle production, although the shape of the particles is not perfectly spherical in all cases. However, parameter adjustment might lead to even better shaped particles in further work. Moreover, the biopolymer-based aerogel particles synthesized in this study were tested as humidity absorber in drying units for home appliances, particularly for dishwashers. It could be shown that for several cycles of absorption and desorption of humidity aerogel particles are stable with an absorption capacity of around 20 wt. %.
Fri, 29 June 2018
ARTICLE Download: 223| View: 243| Comments: 0 | doi:10.20944/preprints201806.0489.v1
Subject: Materials Science, Biomaterials Keywords: antibacterial agent; antibiofilm; ferulic acid grafted chitosan; human pathogenic bacteria
Online: 29 June 2018 (15:21:41 CEST)
Emergence of more virulent forms of human pathogenic bacteria with multi drug resistance is a serious global issue and requires alternative control strategies. The current study was focused to investigate the antibacterial and antibiofilm potential of ferulic acid grafted chitosan (CFA) against Listeria monocytogenes (LM), Pseudomonas aeruginosa (PA), and Staphylococcus aureus (SA). The present result showed that CFA at 64 µg/mL concentration exhibit bactericidal action against LM and SA (>4 log reduction) and bacteriostatic action against PA (<2 log CFU) within 24 h of incubation. Further studies based on propidium iodide uptake assay, measurement of material released from the cell, and electron microscopic analysis revealed that the bactericidal action of CFA was due to the altered membrane integrity and permeability. CFA dose-dependently inhibited biofilm formation (52-89% range), its metabolic activity (30.8-75.1% range) and eradicated mature biofilms, and reduced viability (71-82% range) of the test bacteria. Also, the swarming motility of LM was differentially affected at sub-MIC concentration of CFA. In the present study, the ability of CFA to kill and alter the virulence production in human pathogenic bacteria will insight a new scope for the application of these biomaterials in healthcare to effectively treat bacterial infections.
Tue, 26 June 2018
REVIEW Download: 238| View: 234| Comments: 2 | doi:10.20944/preprints201806.0432.v1
Subject: Materials Science, Biomaterials Keywords: Bone tissue engineering; biomaterials; bone scaffolds; additive manufacturing techniques/robocasting; marine-derived biomaterials
Online: 26 June 2018 (16:05:49 CEST)
Bone is a dynamic tissue with the capacity of repair and regeneration in specific conditions. Nevertheless, due to the increased incidence of bone disorders, the need of bone grafts has been growing over the past decades and the development of an ideal bone graft with optimal properties remains a clinical challenge. This review addresses the bone properties (morphology, composition and their repair and regeneration capacity) and puts the main focus on the potential strategies for developing bone repair and regeneration materials. It describes the requirements for designing a suitable scaffold material, types of materials (polymers, ceramics and composites) and techniques to obtain the porous structures (additive manufacturing techniques/robocasting or derived from marine skeletons) for bone tissue engineering applications. The main objective of this review is to gather the knowledge on the materials and methods for the production of scaffolds for bone tissue engineering and highlighting the potential of natural porous structures such as marine skeletons as promising alternative bone graft substitute materials without any further mineralogical changes, or after partial or total transformation into calcium phosphate. The suitability of the marine-derived porous bone graft substitutes for the intended applications will be also discussed.
Fri, 22 June 2018
COMMUNICATION Download: 149| View: 183| Comments: 0 | doi:10.20944/preprints201806.0353.v1
Subject: Materials Science, Biomaterials Keywords: macromolecular crystallography; X-ray diffraction; radiation damage; absorption; electronic excitations; quantum chemistry
Online: 22 June 2018 (08:15:27 CEST)
Macromolecular crystallography at cryogenic temperatures has so far provided the majority of the experimental evidence that underpins the determination of the atomic structures of proteins and other biomolecular assemblies by means of single crystal X-ray diffraction experiments. One of the core limitations of the current methods is that crystal samples degrade as they are subject to X-rays, and two broad groups of effects are observed: global and specific damage. While the currently successful approach is to operate outside the range where global damage is observed, specific damage is not well understood and may lead to poor interpretation of the chemistry and biology of the system under study. In this work, we present a phenomenological model in which specific damage is understood as the result of a single process, the steady excitation of crystal electrons caused by X-ray absorption, which acts as a trigger for the bulk effects that manifest themselves in the form of global damage and obscure the interpretation of chemical information from XFEL and synchrotron structural research.
Tue, 19 June 2018
ARTICLE Download: 478| View: 183| Comments: 0 | doi:10.20944/preprints201806.0293.v1
Subject: Materials Science, Biomaterials Keywords: fabric classification; fabric wrinkle recovery; PhabrOmeter; directional and side effects
Online: 19 June 2018 (10:47:43 CEST)
It is demonstrated in this study that PhabrOmeter creates genuine wrinkle on fabrics comparable to that in AATCC specifications, and measures fabric wrinkle recovery values fast with repeatable and reliable results with high resolution, over wide range of fabric types. It thus provides an appealing alternative to the existing test methods that are known to be slow, insensitive and unreliable. In addition, with enormous varieties of fabrics, we used a new criterion termed fabric linear density λ so that fabrics can in general be divided into relatively homogeneous groups for further study. The calculation and application of this parameter are showed in this report.
Mon, 18 June 2018
ARTICLE Download: 148| View: 199| Comments: 0 | doi:10.20944/preprints201806.0264.v1
Subject: Materials Science, Biomaterials Keywords: mesoporous silica; surface area; rice husk ash; hydrolysis-ageing time, hydrophobicity
Online: 18 June 2018 (13:38:56 CEST)
This work describes the preparation of mesoporous silica by the green reaction of rice husk ash (RHA) with glycerol, followed by the modification and the potential use as a drug carrier. The reaction was carried out at 215 °C for 2 h. The solution was further hydrolyzed with deionized water and aged for various times (24, 48, 120, 360, 528 and 672 h) before calcinations at 500 oC for 24 h. Further treatment of prepared mesoporous silica was performed using trimethylmethoxysilane (TMMS) to obtain hydrophobic Mesoporous silica. For all synthesized silica, silica contents were as high as 95%wt, whereas organic residues were less than 3%wt. RHA-glycerol showed the highest specific surface area with smallest pore diameter (205.70 m2/g, 7.46 nm) when aged for 48 h. The optimal hydrolysis-ageing period of 120 h resulted in 500.7 m2/g BET surface area, 0.655 cm3/g pore volume and 5.23 nm pore diameter. The surface modification of RHA-glycerol was succeeded through the reaction with TMMS as confirmed by FTIR. Ibuprofen was selected as a model drug for the adsorption experiments. The adsorption under supercritical CO2 was carried out at isothermal temperature of 40 ˚C and 100 bar, % ibuprofen loading of TMMS modified mesoporous silica (TMMS-g-MS) was 6 times less than mesoporous silica aged for 24 h (MS-24h) due to the hydrophobic nature of modified mesoporous silica, not surface and pore characteristics. The release kinetics of ibuprofen-loaded mesoporous silicas were also investigated in vitro. The release rate of ibuprofen-loaded MS-24h was much faster than that of ibuprofen-loaded TMMS-g-MS, but comparable to the crystalline ibuprofen. The slower release rate was attributed to the diffusion control and the stability of hydrophobic nature of modified silica. This would allow the design for the controlled release drug delivery system.
Wed, 13 June 2018
COMMUNICATION Download: 237| View: 221| Comments: 0 | doi:10.20944/preprints201806.0203.v1
Subject: Materials Science, Biomaterials Keywords: Zirconia; primer; priming; bonding; catechol; dental; prosthodontics
Online: 13 June 2018 (06:06:31 CEST)
Zirconia has recently become one of the most popular dental materials in prosthodontics being used in crowns, bridges, and to implants. However, weak bonding strength of dental adhesives and resins to zirconia surface has been a grand challenge in dentistry, thus finding a better adhesion to zirconia is urgently required. Marine sessile organisms such as mussels use a unique priming strategy to produce a strong bonding to wet mineral surfaces; one of the distinctive chemical features in the mussel’s adhesive primer proteins is high catechol contents among others. In this study, we pursued a bioinspired adhesion strategy, using a synthetic catechol primer applied to dental zirconia surfaces to study the effect of catecholic priming to shear bonding strength. Catechol priming provided a statistically significant enhancement (P < 0.05) in shear bonding strength compared to the bonding strength without priming, and relatively stronger bonding than commercially available zirconia priming techniques. This new bioinspired dental priming approach can be an excellent addition to the practitioner’s toolkit to improve dental bonding to zirconia.
Fri, 8 June 2018
ARTICLE Download: 220| View: 202| Comments: 0 | doi:10.20944/preprints201806.0130.v1
Subject: Materials Science, Biomaterials Keywords: wound healing; catechol; conjugated; antioxidant; antiinflammatory; bioadhesion; UV shielding
Online: 8 June 2018 (12:28:07 CEST)
The effective treatment for chronic wounds constitute one of the most common worldwide health care problem due to the presence of high levels of proteases, free radicals and exudates in the wound, which constantly activate the inflammatory system avoiding the tissue regeneration. In this study, we describe a multifunctional bioactive and resorbable membrane with in-built antioxidant agent for the continuous quenching of free radicals as well as to control inflammatory response helping to promote the wound healing process. To reach that goal synthesized statistical copolymers of N-vinylcaprolactam (V) and 2-hydroxyethyl methacrylate (H) have been conjugated with catechol bearing hydrocaffeic acid (HCA) molecules. The natural polyphenol (catechol) is the key molecule responsible for the mechanism of adhesion of mussels, and provides the functionalized polymer conjugate a continuous antioxidant response, antiinflammatory effect, UV screen and bioadhesion in the moist environment of the human body, all of them key features in the wound healing process. Therefore, these novel mussel-inspired materials have an enormous potential of application and can act very positively, favoring and promoting the healing effect in chronic wounds.
Tue, 5 June 2018
ARTICLE Download: 232| View: 248| Comments: 0 | doi:10.20944/preprints201806.0066.v1
Subject: Materials Science, Biomaterials Keywords: molecular graph; degree-based index; silicon-carbon
Online: 5 June 2018 (12:44:44 CEST)
The application of graph theory in chemical and molecular structure research far exceeds people's expectations, and it has recently grown exponentially. In the molecular graph, atoms are represented by vertices and bonded by edges. Closed forms of multiplicative degree-based topological indices which are numerical parameters of the structure and determine physico-chemical properties of the concerned molecular compound. In this article, we compute and analyze many multiplicative degree-based topological indices of silicon-carbon Si2C3-I[p,q] and Si2C3-II[p,q].
ARTICLE Download: 279| View: 413| Comments: 0 | doi:10.20944/preprints201806.0047.v1
Subject: Materials Science, Biomaterials Keywords: biodegradable nanofibers; PLGA; masquelet technique
Online: 5 June 2018 (05:35:14 CEST)
Masquelet induced-membrane technique for the treatment of segmental bone defects includes a two-stage surgical procedure, and polymethylmethacrylate (PMMA) plays a major role in the treatment. However, the PMMA spacer must be surgically removed. Here, we investigated the potential of poly (lactic-co-glycolic acid) (PLGA) nanofibers, a biodegradable material to replace PMMA spacer, allowing the bioactive membrane to be induced, and the spacer to degrade without the additional surgery on a rabbit femoral segmental bone defect model. PLGA nanofibers were shown to degrade completely six weeks after implantation in the investigated animals, and a thick membrane was found to circumferentially fold around the segmental bone defects. Results from image studies demonstrated that, in the group without bone graft, all studied femurs exhibited either nonunion or considerable malunion. In contrast, the femurs in the bone graft group had a high union rate without considerable deformities. Histological examinations suggested that the membranous tissue in this group was rich in small blood vessels and the expression of BMP2 and VEGF increased. Our results demonstrate that the biodegradable PLGA nanofibers may be useful for replacing the PMMA spacer as the bioactive-membrane inducer, facilitating the process of healing and removing the need for repeated surgeries.
Tue, 29 May 2018
ARTICLE Download: 229| View: 275| Comments: 0 | doi:10.20944/preprints201805.0423.v1
Subject: Materials Science, Biomaterials Keywords: shielding agent; polysarcosine; biodistribution; click-chemistry; lipopolyplex; nucleic acid carrier
Online: 29 May 2018 (10:39:48 CEST)
Shielding agents are commonly used to shield polyelectrolyte complexes, e.g. polyplexes, from agglomeration, precipitation in complex media, like blood, and thus enhance their circulation times in vivo. Since up to now primarily poly(ethylene glycol) (PEG) has been investigated to shield non-viral carriers for systemic delivery, we report on the use of polysarcosine (pSar) as a potential alternative for steric stabilization. A redox-sensitive, cationizable lipo-oligomer structure (containing two cholanic acids attached via a bioreducible disulfide linker to an oligoaminoamide backbone in T-shape configuration) was equipped with azide-functionality by solid phase supported synthesis. After mixing with small interfering RNA (siRNA), lipopolyplexes formed spontaneously and were further surface-functionalized with polysarcosines. Polysarcosine was synthesized by living controlled ring-opening polymerization using an azide-reactive dibenzo-aza-cyclooctyne-amine as an initiator. The shielding ability of the resulting formulations was investigated with biophysical assays and by near-infrared fluorescence bioimaging in mice. The modification of ~100 nm lipopolyplexes was only slightly increased upon functionalization. Cellular uptake into cells was strongly reduced by the pSar shielding. Moreover, polysarcosine-shielded polyplexes showed enhanced blood circulation times in bioimaging studies compared to unshielded polyplexes and similar to PEG-shielded polyplexes. Therefore, polysarcosine is a promising alternative for the shielding of non-viral, lipo-cationic polyplexes.
Fri, 25 May 2018
ARTICLE Download: 142| View: 231| Comments: 0 | doi:10.20944/preprints201805.0365.v1
Subject: Materials Science, Biomaterials Keywords: pretreated cellulosic biomass; critical point drying; surface area; pore size distribution; Brunauer-Emmett-Teller; cellulose; hornification
Online: 25 May 2018 (11:57:19 CEST)
Surface area and pore size distribution of Eucalyptus samples pretreated by different methods were determined by the Brunauer-Emmett-Teller (BET) technique. Three methods were applied to prepare cellulosic biomass samples for BET measurements: air, freeze, and critical point drying (CPD). Air and freeze drying caused severe collapse of biomass pore structures, but CPD effectively preserved biomass morphology. Surface area of CPD prepared Eucalyptus samples was determined to be 58–161 m2/g, whereas air and freeze dried samples were 0.5–1.3 and 1.0–2.4 m2/g, respectively. Average pore diameter of CPD prepared Eucalyptus samples were 61–70Å. CPD preserved Eucalyptus sample morphology by replacing water with a non-polar solvent, CO2 fluid, which prevented hydrogen bond reformation in the cellulose.
ARTICLE Download: 219| View: 180| Comments: 0 | doi:10.20944/preprints201805.0343.v2
Subject: Materials Science, Biomaterials Keywords: haemoglobin detection; SPR spectroscopy; biosensors; computer simulation; core-shell [email protected]
Online: 25 May 2018 (10:02:27 CEST)
A theoretical analysis of haemoglobin (Hb) concentration detection is presented in this work with the objective of achieving more sensitive detection and monitoring low concentrations. Surface-enhanced SPR spectroscopy on silver nanoparticles was employed for recording Hb concentrations less than 10 g/L. In this paper, Fe3O4@Au core-shell, nanocomposite spherical nanoparticle consisting of a spherical Fe3O4 core covered by Au shell, was used as an active material for biomolecules detection in the Surface Plasmon Resonance (SPR)-based biosensor in the wavelength 632.8 nm. We present the simulation of detection amplification technique through Attenuated Total Reflection (ATR) spectrum in the Kretschmann configuration. The system consists of a four-layer material i.e prism/Ag/Fe3O4@Au+Hb/air. Dielectric function determination of the core-shell nanoparticle (Fe3O4@Au) and the composite (Fe3O4@Au+Hb) was done by applying the Effective Medium Theory approximation and the calculation of the reflectivity is carried out by varying the size of core-shell (r0). In this simulation, the refractive index of the BK7 prism is 1.51; the refractive index of Ag thin film is 0.13455+3.98651i with the thickness of 40 nm, and the refractive index of the composite is varied depending on the size of nanoparticle core-shell. Our results show that by varying the radius of the core and the shell thickness, the dip of the reflectivity (ATR) spectrum is shifted to the larger angle of incident light and the addition of core-shell in the conventional SPR-based biosensor leads to enhancement of the SPR biosensor sensitivity, for the core-shell radius 10 nm, the sensitivity increased by 1.35% for F = 0.1, and by 4.89% for F =0.8 compared to the sensitivity of the conventional SPR-based biosensor without core-shell addition.
Thu, 24 May 2018
ARTICLE Download: 122| View: 94| Comments: 0 | doi:10.20944/preprints201805.0343.v1
Subject: Materials Science, Biomaterials Keywords: haemoglobin detection; SPR spectroscopy; biosensors; computer simulation; core-shell [email protected]
Online: 24 May 2018 (09:01:27 CEST)
A theoretical analysis of haemoglobin (Hb) concentration detection is presented in this work with the objective of achieving more sensitive detection and monitoring low concentrations. Surface-enhanced SPR spectroscopy on silver nanoparticles was employed for recording Hb concentrations less than 10 g/L. In this paper, Fe3O4@Au core-shell, nanocomposite spherical nanoparticle consisting of a spherical Fe3O4 core covered by Au shell, was used as an active material for biomolecules detection in the Surface Plasmon Resonance (SPR)-based biosensor in the wavelength 632.8 nm. We present the simulation of detection amplification technique through Attenuated Total Reflection (ATR) spectrum in the Kretschmann configuration. The system consists of a four-layer material i.e., prism/Ag/Fe3O4@Au+Hb/air. Dielectric function determination of the core-shell nanoparticle (Fe3O4@Au) and the composite (Fe3O4@Au+Hb) was done by applying the Effective Medium Theory approximation and the calculation of the reflectivity is carried out by varying the size of core-shell (r0). In this simulation, the refractive index of the BK7 prism is 1.51; the refractive index of Ag thin film is 0.13455 + 3.98651i with the thickness of 40 nm, and the refractive index of the composite is varied depending on the size of nanoparticle core-shell. Our results show that by varying the radius of the core and the shell thickness, the dip of the reflectivity (ATR) spectrum is shifted to the larger angle of incident light and the addition of core-shell in the conventional SPR-based biosensor leads to enhancement of the SPR biosensor sensitivity, for the core-shell radius 10 nm, the sensitivity increased by 1.35% for F = 0.1, and by 4.89% for F = 0.8 compared to the sensitivity of the conventional SPR-based biosensor without core-shell addition.
ARTICLE Download: 266| View: 362| Comments: 0 | doi:10.20944/preprints201805.0336.v1
Subject: Materials Science, Biomaterials Keywords: 316L; electrodeposition; nano-hydroxyapatite; carbon nanotubes; osteoblasts; gene expression
Online: 24 May 2018 (06:18:52 CEST)
Herein, we evaluated the electrophoretic deposition of nanohydroxyapatite/superhydrophilic multiwalled carbon nanotube composites (nHAp/MWCNT) onto stainless steel biomedical alloys for applications in bone tissue engineering. First, nHAp/MWCNT composites were dispersed into 0.042 mol L−1 of Ca(NO3)2·4H2O + 0.025 mol L−1 NH4H2PO4 electrolytes (pH = 4.8) at two different concentrations. Next, a voltage of −2 V was applied using 316L stainless steel as a working electrode and (0.27 cm2), a high-purity platinum coil wire as the auxiliary electrode, and an Ag/AgCl(3 M) electrode was used as the reference electrode. The nHAp/MWCNT composites were characterized by transmission electron microscopy. The deposited nHAp and nHAp/MWCNT films were characterized by profilometry, scanning electron microscopy, X-Ray diffractometry and Raman spectroscopy. Human osteoblast cells were cultivated with the different materials, and in vitro cytotoxicity was evaluated using lactate dehydrogenase (LDH) assay. The osteogenesis process was evaluated by mRNA levels of the three genes that are directly related to bone repair: Alkaline Phosphatase, Osteopontin and Osteocalcin. We showed that rough, crystalline apatite thin films containing phases of nHAp were successfully deposited onto 316L stainless steel alloys. Also, we noticed that nHAp/MWCNT thin films deposited onto 316L stainless steel alloys upregulated the expression of important genes related to bone mineralization and maturation. Our results strongly support the possibility of this new alternative to modify the surface of metallic biomedical alloys to promote bone tissue regeneration.
Mon, 21 May 2018
ARTICLE Download: 182| View: 199| Comments: 0 | doi:10.20944/preprints201805.0269.v1
Subject: Materials Science, Biomaterials Keywords: poly(butylene succinate-co-adipate); zinc phenylphosphonate; nanocomposites; crystallization; biodegradation
Online: 21 May 2018 (11:40:10 CEST)
Biocompatible and biodegradable poly(butylene succinate-co-adipate) (PBSA)/hexadecylamine-modified PPZn (m-PPZn) nanocomposites were prepared using a melt mixing process. Experimental results of wide-angle X-ray diffraction and transmission electron microscopy revealed that the stacking layers of the m-PPZn were partially intercalated and partially exfoliated into the PBSA polymer matrix. The isothermal crystallization kinetics of PBSA/m-PPZn nanocomposites were studied at the temperature range of 62−70 °C and the half-time for crystallization of 3 wt % PBSA/m-PPZn nanocomposite was reduced by 27−35% compared with that of pure PBSA. This finding suggests that the incorporation of m-PPZn might cause the heterogeneous nucleation and the subsequent crystallization growth, which enhances the isothermal crystallization rate of PBSA/m-PPZn nanocomposite. The biodegradation rates of PBSA using Lipase from Pseudomonas sp. increase as the contents of m-PPZn increase. The degradation behavior of the neat PBSA investigated using the change of weight-average molecular weight belongs to exo-type hydrolysis activity. It is necessary to point out that the change of degree of crystallinity and degradation rate are almost linearly proportional to the loading of hexadecylamine-modified PPZn. This finding would provide an important information for the manufacturing biodegradable PBSA nanocomposites.
Wed, 9 May 2018
ARTICLE Download: 229| View: 304| Comments: 0 | doi:10.20944/preprints201805.0141.v1
Subject: Materials Science, Biomaterials Keywords: Caenorhabditis elegans; toxicity; gold nanoparticles; nanocomposites; Lectin Protein; ROS
Online: 9 May 2018 (08:11:49 CEST)
The lectin found in the tubers of the Winter Aconite (Eranthis hyemalis) plant (EHL) is a Type II Ribosome Inactivating Protein (RIP); type II RIPs have shown anti-cancer properties, and have great potential as therapeutic agents. Similarly, colloidal gold nanoparticles are successfully used in biomedical applications as gold nanoparticles can be functionalised with ligands with high affinity and specificity for target cells to create therapeutic and imaging agents. Herein we present the synthesis and characterization of gold nanoparticles conjugated with EHL. The aim was to establish the viability of the conjugate and perform a set of initial assays to establish whether the biological effect of EHL is altered by the conjugation. The biological assays were performed in Caenorhabditis elegans, a free living nematode commonly used for toxicological studies; previous work from some of the authors using first life stage (L1) nematodes has shown that EHL has a strong biocidal effect on C. elegans. Gold nanoparticles functionalised with EHL ([email protected]) were successfully synthesised by bioconjugation with citrate gold nanoparticles ([email protected]); the conjugates were analysed by UV-Vis spectroscopy, Dynamic Light Scattering (DLS), Zeta Potential analysis and Transmission Electron Microscopy (TEM). Results indicate that an optimal functionalisation was achieved with the addition of 100 µL of EHL (concentration 1090 ± 40 µg/mL) over 5 mL of AuNPs (concentration [Au0] = 0.8 mM). Biological assays on the effect of [email protected] on C. elegans were performed, using first life stage (L1) and pre-adult stage (L4) nematodes. Citrate gold nanoparticles did not have any obvious effect on the nematodes. For L1 stage nematodes, the assays show that conjugation with gold nanoparticles reduced the biological effect of EHL on C. elegans. As lectin binding activity is essential for the natural protein to bind and allow entry to cells, conformational changes due to conjugation may have affected this binding affinity. For L4 stage nematodes, both EHL alone and [email protected] showed biological activity, and reproductive delays and reduced fecundity were observed in both cases. These assays indicate that EHL can be conjugated to gold nanoparticles and retain elements of biocidal activity.
Mon, 7 May 2018
COMMUNICATION Download: 170| View: 406| Comments: 0 | doi:10.20944/preprints201805.0114.v1
Subject: Materials Science, Biomaterials Keywords: biomass; biochar; activation; activated carbon; thermal treatment, physical activation; porosity, specific surface areas
Online: 7 May 2018 (10:30:25 CEST)
Activated carbons (ACs) can be produced from biomass in a thermal process either in a direct carbonization-activation process or first by carbonizing the biomass and later on activating the biochars into activated carbons. The properties of the ACs are dependent on the type of process used for production. In this study, the properties of activated carbons produced in a one-stage and a two-stage process are considered. Activated carbons were produced by physical activation of two types of starting materials, biochars produced from spruce and birch chips in a commercial carbonization plant and from the corresponding raw chips. The activated carbons produced were characterized regarding specific surfaces, pore volumes and pore size distributions. The unactivated biochars had some degree of surface area and some porosity. According to the results obtained, two slightly different types of activated carbons are produced depending if a one-stage or a two-stage carbonization and activation process is used. The ACs produced in the one-stage process had higher specific surface areas compared to the ones produced in a two-stage process. In addition, total pore volumes were higher in one-stage process but development of micropores is greater compared to two-stage process. There was no significant difference in total carbon content between one-stage and two-stage process.
Fri, 4 May 2018
ARTICLE Download: 231| View: 448| Comments: 0 | doi:10.20944/preprints201805.0093.v1
Subject: Materials Science, Biomaterials Keywords: Peptide; self-assembly; nanomaterial; hydrogel; aspergillosis; candidiasis.
Online: 4 May 2018 (12:58:24 CEST)
The threat of antimicrobial resistance to society is compounded by a relative lack of new clinically effective licensed therapies reaching patients over the past three decades. This has been particularly problematic within antifungal drug development leading to a rise in fungal infection rates and associated mortality. This paper highlights the potential of an ultrashort peptide, (naphthalene-2-ly)-acetyl-diphenylalanine-dilysine-OH (NapFFKK-OH), encompassing hydrogel-forming and antifungal properties within a single peptide motif, thus overcoming formulation (e.g. solubility, drug loading) issues associated with many current employed highly hydrophobic antifungals. A range of fungal susceptibility (colony counts) and cell cytotoxicity (MTS cell viability, LIVE/DEAD staining® with fluorescent microscopy, haemolysis) assays were employed. Scanning electron microscopy confirmed the nanofibrous architecture of our self-assembling peptide, existing as a hydrogel at concentrations of 1% w/v and above. Broad-spectrum activity was demonstrated against a range of fungi clinically relevant to infection (Aspergillus niger, Candida glabrata, Candida albicans, Candida parapsilosis and Candida dubliniensis) with greater than 4 log10 CFU/mL reduction at concentrations of 0.5% w/v and above. We hypothesise antifungal activity is due to targeting of anionic components present within fungal cell membranes resulting in membrane disruption and cell lysis. NapFFKK-OH demonstrated reduced toxicity against mammalian cells (NCTC 929, ARPE-19) suggesting increased selectivity for fungal cells. However, further studies relating to safety for systemic administration is required, given the challenges toxicity has presented in the wider context of antimicrobial peptide drug development. Overall this study highlights the promise of NapFFKK-OH hydrogels, particularly as a topical formulation for the treatment of fungal infections relating to the skin and eyes, or as a hydrogel coating for the prevention of biomaterial related infection.
Wed, 2 May 2018
ARTICLE Download: 228| View: 362| Comments: 0 | doi:10.20944/preprints201805.0021.v1
Subject: Materials Science, Biomaterials Keywords: capsaicin; chitosan; lecithin; dissipative particle dynamics
Online: 2 May 2018 (11:07:01 CEST)
Transport of hydrophobic drugs in the human body exhibits complications due to the low solubility of these compounds. With the purpose of enhancing the bioavailability and biodistribution of such drugs, recent studies have reported the use of amphiphilic molecules, such as phospholipids, for synthesis of nanoparticles or nanocapsules. Given that phospholipids can self–assemble in liposomes or micellar structures, they are ideal candidates to function as vehicles of hydrophobic molecules. In this work, we report mesoscopic simulations of nanoliposomes, constituted by lecithin and coated with a shell of chitosan. The stability of such structure and the efficiency of encapsulation of capsaicin, as well as the internal and superficial distribution of capsaicin and chitosan inside the nanoliposome were analyzed. The characterization of the system was carried out through density maps and the potentials of mean force for the lecithin–capsaicin, lecithin–chitosan and capsaicin–chitosan interactions. The results of these simulations show that chitosan is deposited on the surface of the nanoliposome, as has been reported in some experimental works. It was also observed that a nanoliposome of approximately 18 nm in diameter is stable during the simulation. The deposition behavior was found to be influenced by pattern of N-acetylation of chitosan.
Fri, 20 April 2018
ARTICLE Download: 445| View: 348| Comments: 0 | doi:10.20944/preprints201804.0268.v1
Subject: Materials Science, Biomaterials Keywords: Jute fiber; Starch matrix; Epoxy resin; Biocomposite; Microstructure
Online: 20 April 2018 (13:58:18 CEST)
In this article, bio-composites derived from starch-glycerol biodegradable matrix reinforced with jute fibers have been fabricated using the wet hand lay-up and compression moulding techniques. Samples having different weight percentages of jute fiber in the starch matrix have been analysed. The fibers surface was chemically treated by alkaline sodium hydroxide for improving the interphase bonding between fiber and matrix. Tensile test for the composites were done and the sample with highest tensile strength was selected for further tests that included water absorption, scanning electron microscopy and thermal analysis. It has been concluded that the ultimate tensile strength was found to be maximum for the composition of 15% fiber by weight composite as 7.547 MPa without epoxy coating and 10.43 MPa with epoxy coating. The major disadvantage of bio-composite is its high water absorption property, which in this study has been inhibited by the epoxy resin layer. Herein, the results of various tests done disclose a noteworthy improvement in the overall properties of bio-composite, in comparison to the neat biodegradable starch matrix.
Fri, 16 March 2018
ARTICLE Download: 325| View: 261| Comments: 0 | doi:10.20944/preprints201803.0126.v1
Subject: Materials Science, Biomaterials Keywords: polarization; CoCr alloy; wear particles; hyaluronic acid; macrophages biocompatibility
Online: 16 March 2018 (04:58:28 CET)
Macrophages are cells involved in the primary response to debris derived from wear of implanted CoCr alloys. The biocompatibility of wear particles from a high carbon CoCr alloy produced under polarization in physiological hyaluronic acid (HA) solution was evaluated in J774A.1 mouse macrophages cultures. Polarization was applied to mimic the electrical interactions observed in living tissues. Wear tests were performed in a pin-on-disk tribometer integrating an electrochemical cell in phosphate buffer solution (PBS) and in PBS supplemented with 0.3% HA, physiological synovial fluid concentration, used as lubricant solution. Wear particles produced in 0.3% HA solution showed a higher biocompatibility in J774A.1 macrophages in comparison to those elicited by PBS. A considerable improvement in macrophages biocompatibility in the presence of 0.3 % of HA was further observed by the application of polarization at potentials having current densities typical of injured tissues suggesting that polarization produces an effect on the surface of the metallic material that leads to the production of wear particles that are macrophages biocompatible and less cytotoxic. The results showed the convenience to consider electric interactions together with other particles parameters, as are size and composition, to get a better understanding of the biological effects of the wear products.
Thu, 18 January 2018
ARTICLE Download: 392| View: 434| Comments: 0 | doi:10.20944/preprints201801.0172.v1
Subject: Materials Science, Biomaterials Keywords: amyloids; Gad m 1, EF-hand motif, calcium carbonate precipitation, calcite
Online: 18 January 2018 (15:13:24 CET)
Acid proteins capable of nucleating Ca2+ and displaying aggregation capacity play key roles in the formation of calcium carbonate biominerals. EF-hands are among the largest Ca2+-binding motif in proteins. Gad m 1, an Atlantic cod β-parvalbumin isoform, is a monomeric EF-hand protein that acts as a Ca2+ buffer in fish muscle and is able to form amyloids under acidic conditions. Since nucleating Ca2+ protein have a propensity to form extended β-strand structures, we wondered whether amyloid assemblies of a protein containing refolded EF-hand motifs were able to influence the in vitro calcium carbonate crystallization. Here we have used the Gad m 1 chain as model to generate monomeric and amyloid assemblies and analyze their effect on in vitro calcite formation. We found that only amyloid assemblies alter calcite morphology.
Wed, 17 January 2018
ARTICLE Download: 421| View: 465| Comments: 0 | doi:10.20944/preprints201801.0149.v1
Subject: Materials Science, Biomaterials Keywords: porous scaffold; collagen coating; bioactive peptide; skull defect repair; tissue engineering
Online: 17 January 2018 (06:48:17 CET)
The treatment of large-area bone defects remains a challenge; however, various strategies have been developed to improve the performances of scaffolds in bone tissue engineering. In this study, poly(lactide-co-glycolide)/hydroxyapatite (PLGA/HA) scaffold was coated with Asp-Gly-Glu-Ala (DGEA)-incorporated collagen for the repair of rat skull defect. Our results indicated that the mechanical strength and hydrophilicity of PLGA/HA scaffold were clearly improved and conducive to cell adhesion and proliferation. The collagen-coated scaffold with DGEA significantly promoted the repair of skull defect. These findings indicated that a combination of collagen coating and DGEA improved scaffold properties for bone regeneration, thereby providing a new potential strategy for scaffold design.
Tue, 16 January 2018
ARTICLE Download: 213| View: 303| Comments: 0 | doi:10.20944/preprints201801.0133.v1
Subject: Materials Science, Biomaterials Keywords: testosterone; cellulose bead; chitosan; coating; zinc ion; freeze drying; adsorbent
Online: 16 January 2018 (05:04:16 CET)
Immobilized metal ion affinity adsorbents have been widely used in separation technique to purify proteins. Due to the leakage of metal ion from the adsorbents, there is no metal ion affinity adsorbent for hemoperfusion has been applied to clinical trial. In this study, in order to prevent the leakage of Zn2+ loaded from cellulose beads based adsorbent, improve its stability and adsorption capacity for testosterone, Freeze-drying method was used to enhance the porosity of cellulose beads, improve the surface area of the cellulose beads and adsorption capacity for testosterone. Chitosan was used to coat the adsorbents for preventing the leakage of Zn2+ loaded and improve the adsorbent’s stability. Moreover, the factors affecting adsorption ability and some components in plasma were also investigated. The results indicate the adsorption ability of the adsorbent can be significantly improved by freeze-drying. After the adsorbent was coated with 0.02% chitosan solution, the highest adsorption percentage reached 48%. During adsorption, the Zn2+ concentration in plasma did not rise. In addition, the adsorption percentage for total proteins was below 15%. The results may be caused by the pore size and surface area of the adsorbent enlarged via freeze-drying, and the chitosan solution went into the pores and coated the outer and inner surface of the adsorbent. The adsorbent has a potential clinical application to remove testosterone in patients with recurrent and metastatic prostate cancer.
Sun, 7 January 2018
ARTICLE Download: 328| View: 371| Comments: 0 | doi:10.20944/preprints201801.0037.v1
Subject: Materials Science, Biomaterials Keywords: Emdogain; amelogenin; dental pulp cells; cell differentiation; cell migration; mineralization
Online: 7 January 2018 (11:00:15 CET)
Enamel matrix derivative (EMD) is used for periodontal tissue regeneration therapy, and can induce mineralization in dental pulp cells (DPCs). We designed a synthetic peptide (SP) derived from the response of cells to EMD, and investigated the effect of the SP on potentiating osteogenesis in DPCs, which have a critical role of dental pulp homeostasis. DPCs were treated with 0, 10, 100, or 1000 ng/mL SP to determine its effect on cell proliferation, cell migration, cell differentiation, and mineralization. We then examined the molecular effects of the SP, focusing on changes in the mitogen-activated protein kinases (MAPK) signaling pathway in these cells. The SP significantly promoted DPC proliferation and migration. Cultures treated with the SP also showed an enhanced expression of markers of osteogenic differentiation and mineralization. The SP also induced the activation of MAPK signaling pathway components. These results suggest that our SP could promote the dental pulp tissue repair by hard tissue formation and the mineralization through activating MAPK signaling pathway. This study provides the first evidence that SP might be a new material for dental pulp tissue treatment.
Fri, 5 January 2018
ARTICLE Download: 386| View: 559| Comments: 0 | doi:10.20944/preprints201801.0033.v1
Subject: Materials Science, Biomaterials Keywords: tissue engineering; lumen; stem cells, interstitial cells of Cajal; hydrogel scaffolds
Online: 5 January 2018 (09:36:18 CET)
Gastroparesis (GP) is associated with depletion of interstitial cells of Cajal (ICC) and enteric neurons, which leads to pyloric dysfunction followed by severe nausea, vomiting and delayed gastric-emptying. Regenerating these fundamental structures with stem cell therapy, would be helpful to restore gastric function in GP. Mesenchymal stem cells (MSC) have been successfully used in animal models of other gastrointestinal (GI) diseases including colitis. However, no study has been performed with these cells on GP animals. In this study, we explored if mouse MSC can be delivered from a hydrogel-scaffold to the luminal surfaces of GP mice stomach. Mouse MSC was seeded atop alginate-gelatin, coated with poly-L-lysine. These cell-gel constructs were placed atop stomach explants facing the luminal side. MSC grew uniformly all across the gel surface within 48 hr. When placed atop the lumen of the stomach, MSC migrated from the gels to the tissues as confirmed by positive staining with Vimentin and N-cadherin. The feasibility of transplanting a cell-gel construct to deliver stem cells in the stomach wall was successfully shown in a mice GP model, thereby making a significant advance towards envisioning the transplantation of an entire tissue-engineered ‘gastric patch’ or ‘microgels’ with stem cells, and growth factors.
Thu, 14 December 2017
ARTICLE Download: 489| View: 403| Comments: 0 | doi:10.20944/preprints201712.0087.v1
Subject: Materials Science, Biomaterials Keywords: pyrolysis; biomass; biochar; Taguchi; optimization
Online: 14 December 2017 (08:03:42 CET)
This research demonstrates the optimization and production of biochar from barley husk (BH), corn cob (CC), and Agave salmiana leaves (AL) via pyrolysis in a muffle furnace. Taguchi experimental design (L9) was applied to conduct the experiments at different levels by altering four operating parameters. Carbonization temperature (300–500 ºC), carbonization time (30–90 min), precursor mass (2–5 g) and N2 flow rate (100–200 cc/min) were the variables examined in this study. The effect of the parameters on the biochar yield was investigated, and the important parameters were identified employing analysis of variance (ANOVA). The optimum conditions for maximum biochar yield were: carbonization temperature of 400 ºC, carbonization time of 30 min, precursor mass of 2 g, and N2 flow rate of 150 cc/min. The biochars produced under optimum conditions was characterized physically and chemically. Biochar yields of 19.75% for corn cob (CCB), 32.88% for barley husk (BHB), and 31.14% for agave leaves (ALB) were obtained.
ARTICLE Download: 712| View: 385| Comments: 0 | doi:10.20944/preprints201712.0086.v1
Subject: Materials Science, Biomaterials Keywords: activated carbon; barley husk; corn cob; agave leaves; biomass; thermogravimetry
Online: 14 December 2017 (07:46:00 CET)
Biomass is a promising alternative and renewable energy source that can be transformed into other value-added products such as activated carbon. In this research, barley husk, corn cob and Agave salmiana leaves were characterized to determine their chemical composition and morphology to evaluate their potentiality as precursors of activated carbons. Based on the main composition results obtained, the biomass samples have suitable chemical and physical characteristics to be considered as good precursors of activated carbons, such as carbon contents greater than 40%, ash content less than 10%, moisture content less than 30%, high volatile contents with values from 75 to 80% and a porous and fibrous morphology. The results indicate that the main compositions in the biomass were cellulose and lignin. The cellulose content was more than lignin (15–26%) for the residues selected. Specifically, a-cellulose contents with values from 52% to 79%, β-cellulose contents of 13–44%, γ-cellulose contents less than 11%, and holocellulose contents of 82–83% were determined. The thermal decomposition for the biomass samples proceeded with five stages attributed to the evaporation of some volatile compounds (70–150 ºC), to the degradation of hemicellulose (180–230 ºC), to the cellulose volatilization (250–350 ºC), to the lignin decomposition (380–550 ºC), and to the degradation of complex polymers and inorganic salts, respectively. The stage corresponding to the cellulose decomposition showed rapid mass decreased in the three residues. This results show that the cellulose and lignin content is another important parameter to evaluate the pyrolysis characteristics of a good precursor of activated carbon.
Wed, 29 November 2017
ARTICLE Download: 364| View: 607| Comments: 0 | doi:10.20944/preprints201711.0189.v1
Subject: Materials Science, Biomaterials Keywords: biocomposite films; gelatin; oleoresins; antimicrobial compounds; food quality
Online: 29 November 2017 (10:23:11 CET)
This study developed gelatin-based films with incorporation of microcrystalline cellulose as reinforcement material. Clove (Syzygium aromaticum), nutmeg (Myristica fragrans), and black pepper (Piper nigrum) oleoresins containing antimicrobial compounds of natural origin were incorporated into films. The mechanical, thermal, optical, and structural properties, as well as color, resistance to sealing and permeability to water vapor, light, and oil of the films were determined. Adding oleoresins to the gelatin matrix increased elongation of the material and significantly diminished its permeability to water vapor and oil. Evaluation of the potential use of films containing different oleoresins as bread packaging material was influenced by the film properties. The biocomposite film containing oleoresin from black pepper was the most effective packaging material for maintaining the bread’s quality characteristics.
Wed, 15 November 2017
ARTICLE Download: 613| View: 369| Comments: 0 | doi:10.20944/preprints201710.0049.v3
Subject: Materials Science, Biomaterials Keywords: halloysite nanotubes; surface modification; structural characteristics; controlled release; biocompatibility
Online: 15 November 2017 (07:55:33 CET)
Halloysite nanotubes (HNTs) are natural occurring mineral clay nanotubes that have excellent application potential in different fields. However, HNTs are heterogeneous in size, surface charge and formation of surfacial hydrogen bond, which lead to weak affinity and aggregation at a certain extent. It is very important to modify the HNTs’ surface to expand its applications. In this review, the structural characteristics, performance and the related applications of surface-modified HNTs are reviewed. We focus on the surface-modified variation of HNTs, the effects of surface modification on the materials and related applications in various regions. In addition, future prospects and the meaning of surface modification were also discussed in HNTs studies. This review provides a reference for the application of HNTs modifications in the field of new nanomaterials.
Thu, 2 November 2017
ARTICLE Download: 282| View: 371| Comments: 0 | doi:10.20944/preprints201710.0049.v2
Subject: Materials Science, Biomaterials Keywords: halloysite nanotubes; surface modification; structural characteristics; application
Online: 2 November 2017 (07:12:01 CET)
Halloysite nanotubes (HNTs) are natural occurring mineral clay nanotubes that have excellent potential application in different fields. However, HNTs are affected by size, surface electron and hydrogen bond formation on the surface which lead to weak affinity and reunion at certain extent. It is very significant to modify the HNTs’ surface to expand its applications. In this review, the structural characteristics, performance and the related applications of surface modification HNTs are reviewed and summarized. We focus on the surface modify methods of HNTs, the effect of surface modification on materials and related applications in various regions. In addition, future prospects and the meaning of surface modification were also be discussed in HNTs studies. This review provided a reference for the application of HNTs modifications in new nanomaterials fields.
Sun, 22 October 2017
ARTICLE Download: 591| View: 391| Comments: 0 | doi:10.20944/preprints201710.0144.v1
Online: 22 October 2017 (14:32:49 CEST)
This study evaluated the effects of fluoride on subsurface enamel demineralization induced by two commonly used chemical models. Forty-eight enamel blocks were demineralized at pH = 5.0 by an acetate buffer (Group 1), a lactate buffer (Group 2), an acetate buffer with 0.02 ppm fluoride (Group 3) and a lactate buffer with 0.02 ppm fluoride (Group 4) at 25 °C for 3 weeks. The surface destruction percentage (SDP), mineral loss and lesion depth of the blocks were studied using micro-computed tomography. An elemental analysis of the enamel surface was evaluated using an energy-dispersive X-ray spectroscopy. Surface micro-hardness was determined by the Knoop Hardness Test. The mean lesion depth of Groups 1 through 4 were 134.1 ± 27.2 µm, 96.1 ± 16.5 µm, 97.5 ± 22.4 µm and 91.1 ± 16.2 µm, respectively (p < 0.05; group 1 > 2, 3 > 4). The SDPs of groups 1 through 4 were 7.8 ± 8.93%, 0.71 ± 1.6%, 0.36 ± 1.70% and 1.36 ± 2.94% (p < 0.01; group 1 > 2, 3, 4). The fluoride in mean weight percentages of groups 1 through 4 were 1.12 ± 0.24%, 1.10 ± 0.20%, 1.45 ± 0.40% and 1.51 ± 0.51%, respectively (p < 0.01; group 3,4 > 1,2). The mean Knoop hardness values of groups 1 through 4 were 27.5 ± 13.3, 39.7 ± 19.3, 73.6 ± 44.2 and 91.0 ± 57.2, respectively (p < 0.01; group 4 > 3 > 2 > 1). The chemical model using an acetate buffer solution created significantly deeper zones of subsurface demineralization on enamel than the lactate buffer solution. An acetate buffer may damage the enamel surface, but the surface damage can be prevented by adding fluoride.
Fri, 20 October 2017
ARTICLE Download: 413| View: 334| Comments: 0 | doi:10.20944/preprints201710.0134.v1
Subject: Materials Science, Biomaterials Keywords: chemical treatment; cantala fiber; mechanical properties; recycled high-density polyethylene
Online: 20 October 2017 (03:19:47 CEST)
The improvement of mechanical properties of cantala fiber and its composites. Treatments including alkali, silane, and the combination of both were carried out to modify the fiber surface. The influence of chemical treatments on fiber properties such as the degree of crystallinity and tensile strength was investigated. A variety of short cantala fiber reinforced rHDPE composites were produced by hot press, and the effect of fiber treatment on the flexural strength of composites was observed. SEM observations also carried out to highlight these changes. The result shows that alkali treatment improves tensile strength and tensile modulus of alkali treated fiber (NF12) which was predicted as a result of the enhancement of the cellulose crystallinity. In contrast, the tensile strength and tensile modulus of silane (SF05) and alkali-silane treated fiber (NSF05) decreased compared to untreated fiber (UF) which is caused by the addition of amorphous material. The tensile strength of alkali-silane treated fiber (NSF05) was lower than alkali treated fiber (NF12), but the composites prepared with NSF05 showed the highest increment of flexural strength of 25.9%. This may be due the combination of alkali and silane treatment helped in the better formation of fiber-matrix interface adhesion.
Tue, 17 October 2017
CASE REPORT Download: 413| View: 557| Comments: 0 | doi:10.20944/preprints201710.0116.v1
Subject: Materials Science, Biomaterials Keywords: biomineralization; calcium enriched material; calcium deficient hydroxyapatite; dentinal tubule; energy dispersive spectroscopy; scanning electron microscopy
Online: 17 October 2017 (11:50:20 CEST)
This case report describes evidence of intratubular biomineralization in root canal filled with calcium enriched material after 8 years of clinical maintenance. The schematic findings of dentinal tubules were investigated with scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The root canal obturation material was closely adapted to root dentin surface, suggesting the possibility of chemical bonding between the two interfaces. SEM and EDS observation of dentinal tubules showed intratubular biomineralized crystal structures with Ca/P ratio in a range of 1.30–2.12, suggesting bioactive capacity of calcium enriched cement.
Mon, 9 October 2017
ARTICLE Download: 690| View: 345| Comments: 0 | doi:10.20944/preprints201710.0049.v1
Subject: Materials Science, Biomaterials Keywords: halloysite nanotubes; surface modification; structural characteristics; application
Online: 9 October 2017 (11:47:54 CEST)
Halloysite nanotubes (HNTs) are natural occurring mineral clay nanotubes that have excellent application potential in different fields. However, HNTs are affected by size effect, surface electron effect and hydrogen bond formation on the surface which lead to weak affinity and prone to reunion at some extent. It is very significant to modify the HNTs’ surface for expand its applications. In this review, the structural characteristics, performance and the related applications of surface modification HNTs are reviewed and summarized. we focus on the surface modified methods of HNTs, the effect of surface modification on materials and its related applications in various regions. In addition, future prospects and the meaning of surface modification have been discussed in HNTs studies. This review provided a reference for the application of HNTs modifications in new fields.
Mon, 4 September 2017
ARTICLE Download: 545| View: 437| Comments: 0 | doi:10.20944/preprints201709.0010.v1
Online: 4 September 2017 (18:25:01 CEST)
Titanium membranes are used for guided bone regeneration in implant therapy. However, as a bioinert material, titanium does not have the ability to accelerate bone formation. Various titanium surface treatments to confer bioactivity have been demonstrated; however, there are concerns about the influence of chemical treatments on the corrosion of thin titanium membranes. This study investigated the influence of surface modifications on the structure of thin titanium membranes. Titanium membranes of 20 µm thickness were treated with acid or alkali solutions, and we evaluated their surface structure, wettability, corrosion depth, and mechanical strength compared to non-treated membranes. Alkali-treated thin titanium membranes displayed the formation of nanoscale pore structures on their surfaces, enhanced hydrophilicity, and less corrosion depth compared with acid-treated membranes. Furthermore, the tensile strength of alkali-treated membranes was comparable to non-treated membranes. These results suggest that alkali treatment is an appropriate surface modification method for thin titanium membranes.
Thu, 17 August 2017
ARTICLE Download: 849| View: 1068| Comments: 0 | doi:10.20944/preprints201708.0059.v1
Subject: Materials Science, Biomaterials Keywords: moso bamboo; quasi-static behavior; tensile behavior; size effect on energy absorption; damage pattern of the multiple bamboo columns; macroscopic tensile fracture mode
Online: 17 August 2017 (07:53:23 CEST)
In this paper, quasi-static axial compression tests are performed on the nodal Moso bamboos to study the size effect on energy absorption of the bamboos and the damage pattern of the multiple bamboo columns. Experimental results show that under the same moisture content, growth age and growing environment, the specific energy absorption (SEA) of the test samples increases with the increase of the out-diameter and thickness of the bamboo columns, indicating that size effect exists for energy absorption of the Moso Bamboos. For the multiple bamboo columns, there are mainly three failure modes for the constituent single bamboo columns: splitting above the node, splitting below the node and splitting through the node. Also, the tensile tests are conducted on three kinds of dog-bone shaped bamboo samples to investigate the macroscopic tensile fracture mode in the longitudinal direction of Moso bamboos. Results show that there is no direct relationship between the fracture pattern and moisture content of the bamboos, as well as the growth age of the bamboos. However, the tensile loading rate and the shape of the dog-bone shaped bamboo sample could affect the macroscopic fracture pattern of the bamboos in some cases.
Tue, 11 July 2017
ARTICLE Download: 434| View: 624| Comments: 1 | doi:10.20944/preprints201707.0023.v1
Subject: Materials Science, Biomaterials Keywords: temporomandibular joint disc; reconstituted collagen template; tissue regeneration
Online: 11 July 2017 (16:23:01 CEST)
Previous study demonstrated the reconstituted type I collagen matrix extracted from rabbit tendons enabled to regenerate the TMJ disc in the rabbit. The aim of this study was to investigate changes in the extracellular matrix (ECM) and mechanisms of regeneration in TMJ disc. In 36 New Zealand rabbits that underwent a partial discectomy, discs were replaced with reconstituted collagen templates for 3 months. A histological analysis showed that moderate to severe degeneration appeared in partially discectomized joints without implantation. In contrast, discs that received the reconstituted collagen template regenerated, and returned to normal to protect the joint. Cells in the regenerative tissue expressed ECM, and fibers became regular and compact due to tissue remodeling over time. Reparative cells differentiated into chondroblasts, and showed highly dense pericellular fibers. The morphology and collagen composition of the disc and condyle in the 3-month experimental group were similar to those of normal tissues. In conclusion, the reconstituted collagen template facilitated the regeneration of surgically discectomized discs. Type I and type II collagens play a crucial role in the regeneration of articular discs.
Thu, 22 June 2017
ARTICLE Download: 467| View: 622| Comments: 0 | doi:10.20944/preprints201706.0106.v1
Subject: Materials Science, Biomaterials Keywords: Tricalcium phosphate putty scaffold; bioactive ceramics; bone formation, osteogenesis, osteogenic markers, hard tissue histology; immunohistochemical analysis; split-mouth design; sinus floor augmentation; bone grafting materials
Online: 22 June 2017 (18:33:01 CEST)
This study examines the effect of a hyaluronic acid (HyAc) containing tricalcium phosphate putty scaffold material (TCP-P) and of a particulate tricalcium phosphate (TCP-G) graft on bone formation, volume stability and osteogenic marker expression in biopsies sampled 6 months after bilateral sinus floor augmentation (SFA) in 7 patients applying a split-mouth design. Biopsies were processed for immunohistochemical analysis of resin embedded sections. Sections were stained for collagen type I (Col I), alkaline phosphatase (ALP), osteocalcin (OC) and bone sialoprotein (BSP). Furthermore, the bone area and particle area fraction were determined histomorphometrically. Cone-beam CT data recorded after SFA and 6 month later were used for calculating the graft volume at these two time points. TCP-P displayed more advantageous surgical handling properties and a significantly greater bone area fraction and smaller particle area fraction. This was accompanied by significantly greater expression of Col I and BSP and in osteoblasts and osteoid and a less pronounced reduction in grafting volume with TCP-P. SFA using both types of materials resulted in formation of sufficient bone volume for facilitating stable dental implant placement with all dental implants having been in function without any complications for 6 years. Since TCP-P displayed superior surgical handling properties and greater bone formation than TCP-G, without the Hyac hydrogel matrix having any adverse effect on bone formation or graft volume stability, TCP-P can be regarded as excellent grafting material for SFA in a clinical setting.
Tue, 13 June 2017
ARTICLE Download: 588| View: 627| Comments: 0 | doi:10.20944/preprints201706.0060.v1
Subject: Materials Science, Biomaterials Keywords: β-amyloid 42; differential pulse voltammetry; Neuro-degenerative disorders; ferrocyanide/ferricyanide redox couple
Online: 13 June 2017 (18:14:57 CEST)
A simple in vitro biosensor for the detection of β-amyloid 42 in phosphate-buffer saline (PBS) and undiluted human serum was fabricated and tested based on our platform sensor technology. The bio-recognition mechanism of this biosensor was based on the effect of the interaction between antibody and antigen of β-amyloid 42 to the redox couple probe of K4Fe (CN) 6 and K3Fe (CN) 6. Differential pulse voltammetry (DPV) served as the transduction mechanism measuring the current output derived from the redox coupling reaction. The biosensor was a three-electrode electrochemical system, and the working and counter electrodes were 50 nm thin gold film deposited by sputtering technique. The reference electrode was a thick-film printed Ag/AgCl electrode. Laser ablation technique was used to define the size and structure of the biosensor. Cost-effective roll-to-roll manufacturing process was employed in the fabrication of the biosensor making it simple and relatively inexpensive. Self-assembled monolayers (SAM) of 3-Mercaptopropionic acid (MPA) was employed to covalently immobilize the thiol group on the gold working electrode. A carbodiimide conjugation approach using N-(3-dimethylaminopropyl)-N’-ethylcarbodiimide hydrochloride (EDC) and N–hydroxysuccinimide (NHS) was undertaken for cross-linking antibody of β-amyloid 42 to the carboxylic groups on one end of the MPA. The antibody concentration of β-amyloid 42 used was 18.75µg/mL. The concentration range of β-amyloid 42 in this study was from 0.0675µg/mL to 0.5µg/mL for both PBS and undiluted human serum. DPV measurements showed excellent response in this antigen concentration range. Interference study of this biosensor was carried out in the presence of Tau protein antigen. Excellent specificity of this β-amyloid 42 biosensor was demonstrated without interference by other species such as T-tau protein.
Fri, 2 June 2017
ARTICLE Download: 360| View: 526| Comments: 0 | doi:10.20944/preprints201706.0011.v1
Subject: Materials Science, Biomaterials Keywords: EGF; PS NPs; cellular uptake; clathrin-mediated endocytosis
Online: 2 June 2017 (05:23:52 CEST)
The interaction between nanoparticles and cells has been studied extensively, but most research has focused on the effect of various nanoparticle characteristics, such as size, morphology, and surface charge, on the cellular uptake of nanoparticles. In contrast, there have been very few studies to assess the influence of cellular factors, such as growth factor responses, on the cellular uptake efficiency of nanoparticles. The aim of this study was to clarify the effects of epidermal growth factor (EGF) on the uptake efficiency of polystyrene nanoparticles (PS NPs) by A431 cells, a human carcinoma epithelial cell line. The results showed that EGF enhanced the uptake efficiency of A431 cells for PS NPs. In addition, inhibition and localization studies of PS NPs and EGF receptors (EGFRs) indicated that cellular uptake of PS NPs is related to the binding of EGF-EGFR complex and PS NPs. Different pathways are used to enter the cells depending on the presence or absence of EGF. In the presence of EGF, cellular uptake of PS NPs is via clathrin-mediated endocytosis, whereas in the absence of EGF, uptake of PS NPs does not involve clathrin-mediated endocytosis. Our findings indicate that EGF enhances cellular uptake of PS NPs by clathrin-mediated endocytosis. This result could be important for developing safe nanoparticles and their safe use in medical applications.
Thu, 1 June 2017
ARTICLE Download: 657| View: 642| Comments: 0 | doi:10.20944/preprints201706.0004.v1
Subject: Materials Science, Biomaterials Keywords: hydroxyapatite, xenografts; implant design; implant surface
Online: 1 June 2017 (06:19:41 CEST)
The aim of the present study was to monitor implant stability after sinus floor elevation with two biomaterials during the first 6 months of healing by a resonance frequency analysis (RFA), and how physico-chemical properties affect the implant stability quotient (ISQ) at the placement and healing sites. Bilateral maxillary sinus augmentation was performed in 10 patients in a split-mouth design using a bobine HA (BBM) as a control and porcine HA (PBM). Six months after sinus lifting, 60 implants were placed in the posterior maxilla. The ISQ was recorded on the day of surgery from RFA at T1 (baseline), T2 (3 months), and T3 (6 months). Statistically significant differences were found in the ISQ values during the evaluation period. The ISQ (baseline) was 63.8±2.97 for BBM and 62.6±2.11 for PBM. The ISQ (T2) was ~ 73.5±4.21 and 67±4.99, respectively. The ISQ (T3) was ~ 74.65±2.93 and 72.9±2.63, respectively. All the used HAs provide osseointegration and statistical increases in the ISQ at baseline, T2 and T3 (follow-up), respectively. The BBM, sintered at high temperature with high crystallinity and low porosity, presented higher stability, which demonstrates that variations in the physico-chemical properties of a bone substitute material clearly influence implant stability.
Tue, 18 April 2017
ARTICLE Download: 735| View: 675| Comments: 0 | doi:10.20944/preprints201704.0113.v1
Subject: Materials Science, Biomaterials Keywords: polymethylmethacrylate PMMA; henna; physical properties; hardness; surface roughness
Online: 18 April 2017 (12:24:49 CEST)
Statement of problem: Henna has been added to polymethylmethacrylate (PMMA) as a new type of antifungal agent; however, its effect on the latter’s physical properties has not been investigated. Purpose: This study aimed to evaluate the effect of the addition of various henna concentrations on the surface roughness and hardness of PMMA denture base material. Materials and Methods: A total of 99 specimens of rectangular-shaped (10×20×3 mm3) acrylic specimens were prepared from heat-cured acrylic resin. Specimens were divided into one control group without the addition of henna and five test groups, which were prepared by adding Yamani henna powder to acrylic powder at concentrations of 1wt%, 2.5wt%, 5wt%, 7.5wt%, and 10wt%. The polymer was added to the monomer before being mixed, packed, and processed using the conventional water bath method. After processing, specimens were finished and polished, then kept in distilled water for 48+2 h. A profilometer and Vickers hardness tester were used to measure surface roughness and hardness respectively. Statistical data analysis was conducted via SPSS version 20.0 (IBM, USA). Results: The addition of henna at varying concentrations significantly increased surface roughness values (P ≤ 0.01) while decreasing hardness (P ≤ 0.0001). The most favorable addition value was 1% henna between all henna groups. Conclusion: The addition of henna to the acrylic resin may negatively affect the surface properties of PMMA acrylic denture base.
Mon, 3 April 2017
ARTICLE Download: 1014| View: 1029| Comments: 0 | doi:10.20944/preprints201704.0005.v1
Subject: Materials Science, Biomaterials Keywords: Soy protein isolate; Microcrystalline cellulose; Metal nanoclusters; Nanocomposite film; Tensile strength
Online: 3 April 2017 (16:42:12 CEST)
Soy protein isolate (SPI) based materials are abundant, biocompatible, renewable, and biodegradable. In order to improve the tensile strength (TS) of SPI films, we prepared a novel composite film modified with microcrystalline cellulose (MCC) and metal nanoclusters (NCs) in this research. The effects of the modification of MCC on the properties of SPI-Cu NCs and Zn NCs films were investigated. Attenuated total reflectance-Fourier transformed infrared spectroscopy analyses and X-ray diffraction patterns characterized the strong interactions and reduction of the crystalline structure of the composite films. Scanning electron microscope showed the enhanced cross-linked and entangled structure of modified films. Compared with untreated SPI film, the tensile strength of the SPI-MCC-Cu and SPI-MCC-Zn films increased from 2.91 MPa to 13.95 and 6.52 MPa, respectively. Moreover, the results also indicated their favorable water resistance with higher water contact angle. Meanwhile, the composite films exhibited increased initial degradation temperatures, demonstrating their higher thermostability. The results suggested that MCC could effectively improve the performance of SPI-NCs films, which would provide a novel preparation method for environmentally friendly SPI-based films in the applications of packaging materials.
Fri, 31 March 2017
ARTICLE Download: 658| View: 697| Comments: 0 | doi:10.20944/preprints201703.0226.v1
Subject: Materials Science, Biomaterials Keywords: hydroxyapatite; xenografts; physicochemical-characterization; tissue reaction
Online: 31 March 2017 (08:35:07 CEST)
Detailed information about graft material characteristic is crucial to evaluate their clinical outcomes. The present study evaluates the physicochemical characteristics of two xenografts manufactured on an industrial scale deproteinized at different temperatures (non-sintered and sintered) in accordance with a protocol previously used in sinus lift procedures. It compares how the physico-chemical properties influence the material performance in vivo with a histomorphometric study in retrieved bone biopsies following maxillary sinus augmentation, in 10 clinical cases. X-ray diffraction analysis revealed typical structure of hydroxyapatite for both materials. Both xenografts are porous and exhibit intraparticle pores. Strong differences were observed in terms of porosity, cristallinity, and calcium/phosphate. Histomorphometric measurements on the bone biopsies showed statistically significant differences. The physicochemical assessment of both xenografts in accordance with the protocol developed at industrial scale confirmed that these products present excelent biocompatibilitity, with characteristics similar to natural bone. The sintered HAs xenograft exhibit higher osteoconductivity although were not complete resorbable (30.80±0.88% residual material). On the other hand, the non-sintered HAs xerograft induced about 25.92±1.61% of new bone and almost complete degradation after 6 months implantation. Differences in physico-chemical characteristics found between the two HAs xenograft determine different behavior of this material.
Tue, 28 March 2017
ARTICLE Download: 711| View: 826| Comments: 0 | doi:10.20944/preprints201703.0212.v1
Subject: Materials Science, Biomaterials Keywords: hydroxyapatite; xenografts; scanning electron microscopy; degradation; resorption; Ca/P ratio; bone response; biocompatibility
Online: 28 March 2017 (17:09:44 CEST)
Some studies have demonstrated that in vivo degradation processes are influenced by the material’s physico-chemical properties. The present study compares two hydroxyapatites manufactured on an industrial scale, deproteinized at low and high temperatures, and how physico-chemical properties can influence the mineral degradation process of material performance in bone biopsies retrieved 6 months after maxillary sinus augmentation. Residual biomaterial particles were examined by field scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) to determine the composition and degree of degradation of the bone graft substitute material. According to the EDX analysis, the Ca/P ratio significantly lowered in the residual biomaterial (1.08±0.32) compared to the initial composition (2.22±0.08) for the low-temperature sintered group, which also presented high porosity, low crystallinity, low density, a large surface area, and poor stability and a high resorption rate compared to the high-temperature sintered material. This demonstrates that variations in the physico-chemical properties of bone substitute material clearly influence the degradation process. Further studies are needed to determine whether the resorption of deproteinized bone particles proceeds slowly enough to allow sufficient time for bone maturation to occur.
Wed, 15 March 2017
ARTICLE Download: 900| View: 750| Comments: 0 | doi:10.20944/preprints201703.0099.v1
Subject: Materials Science, Biomaterials Keywords: stone matrix asphalt; volume parameters; Marshall Stability; flocculent lignin fiber; polyester fiber; mineral fiber; fiber content
Online: 15 March 2017 (08:25:11 CET)
Lignin fibers typically influence the mixture performance of stone matrix asphalt (SMA), such as strength, stability, durability, noise level, rutting resistance, fatigue life, and water sensitivity. However, limited studies were conducted to analyze the influence of fibers on the percent voids in mineral aggregate in bituminous mixture (VMA) during the mixture design. This study analyzed the effect of different fibers and fiber contents on the VMA in SMA mixture design. A surface-dry condition method test and Marshall Stability test were applied on the SMA mixture with four different fibers (i.e., flocculent lignin fiber, mineral fiber, polyester fiber, blended fiber). The test results indicated that the bulk specific gravity of SMA mixtures and asphalt saturation decreased with the increasing fiber content, whilst the percent air voids in bituminous mixtures (VV), Marshall Stability and VMA increased. Mineral fiber had the most obvious impact on the bulk specific gravity of bituminous mixtures, while flocculent lignin fiber had a minimal impact. The mixture with mineral fiber and polyester fiber had significant effects on the volumetric properties, and, consequently, exhibited better VMA over the conventional SMA mixture with lignin fiber. Modified fiber content range was also provided, which will widen the utilization of mineral fiber and polyester fiber in the applications of SMA mixtures. The mixture evaluation suggested no statistically significant difference between lignin fiber and polyester fiber on the stability. The mineral fiber required a much larger fiber content to improve the mixture performance than other fibers. Overall, the results can be a reference to guide SMA mixture design.
Tue, 14 March 2017
ARTICLE Download: 826| View: 730| Comments: 0 | doi:10.20944/preprints201703.0085.v1
Subject: Materials Science, Biomaterials Keywords: TCP-C2S, Nurse ´A ceramic, Biomaterials, adult human mesenchymal stem cells, Solid State Reaction, Biomedical applications.
Online: 14 March 2017 (13:43:13 CET)
The purpose of this study was to evaluate the bioactivity and cell response of a well-characterized Nurse´s A-phase (7CaO•P2O5•2SiO2) ceramic and his effect compared to a control (tissue culture polystyrene-TCPS) on the adhesion, viability, proliferation and osteogenic differentiation of ahMSCs in vitro. Cell proliferation (Alamar Blue Assay), Alizarin Red-S (AR-s) staining, alkaline phosphatase (ALP) activity, osteocalcin (OCN) and collagen I (Col I) were evaluated. Also, field emission scanning electron microscopy (FESEM) images were acquired in order to visualise the cells and the topography of the material. The proliferation of cells growing in a direct contact with the material was slower at early stages of the study because of the new environmental conditions. However, the entire surface was colonized after 28 days of culture in growth medium (GM). Osteoblastic differentiation markers were significantly enhanced in cells growing on Nurse´s A phase ceramic and cultured with osteogenic medium (OM), probably due to the role of silica to stimulate the differentiation of ahMSCs. Moreover, calcium nodules were formed under the influence of ceramic material. Therefore, it is predicted that Nurse´s A-phase ceramic would present high biocompatibility and osteoinductive properties being a good candidate to be used as a biomaterial for bone tissue engineering.
REVIEW Download: 1660| View: 815| Comments: 0 | doi:10.20944/preprints201703.0072.v1
Subject: Materials Science, Biomaterials Keywords: micro-arc oxidation; antibacterial ability; Ag; Cu; Zn
Online: 14 March 2017 (07:49:40 CET)
Ti and its alloys are the most commonly used materials for biomedical applications. However, bacterial infection after implant placement is still one of the significant rising complications. Therefore, the application of the antimicrobial agents into implant surfaces to prevent implant-associated infection has attracted lots of attention. Scientific papers have shown that inorganic antibacterial metal element (e.g. Ag, Cu, Zn) can be introduced to implant surfaces with the addition of metal nanoparticles or metallic compounds into electrolyte via micro-arc oxidation (MAO) technology. In this review, the effects of the composition and concentration of electrolyte and process parameters (e.g. voltage, current density, oxidation time) on morphological characteristics (e.g. surface morphology, bonding strength), antibacterial ability and biocompatibility of MAO antimicrobial coating were discussed in detail. Anti-infection and osseo-integration can be simultaneously accomplished with the selection of the proper antibacterial elements and operating parameters. Besides, MAO assisted by magnetron sputtering (MS) to endow Ti-based implant materials with superior antibacterial ability and biocompatibility was also discussed. Finally, the development trend of MAO technology in the future was forecasted.
Mon, 6 March 2017
ARTICLE Download: 871| View: 801| Comments: 0 | doi:10.20944/preprints201703.0023.v1
Subject: Materials Science, Biomaterials Keywords: luffa sponge fiber bundles; mechanical properties; anatomical characteristic; moisture regain; thermal performance
Online: 6 March 2017 (04:32:21 CET)
The advancement in science and technology has led to luffa sponge (LS) being widely used as a natural material in industrial application as its polyporous structure and light texture. In order to enhance the utility of LS fibers as the reinforcement of lightweight composite materials, this study investigate its water absorption, mechanical properties, anatomical characteristic and thermal performance. Hence, moisture regain, tensile properties of LS fiber bundles were measured in accordance with standards and the structural characteristics were investigated via microscopic observation. Scanning electron microscopy (SEM) was used to observe the surface morphology and fracture surface of fiber bundles. Test results shows that the special structure where the phloem tissues degenerate to cavities had a significant influence on the mechanical properties of LS fiber bundles. Additionally, the transverse sectional area occupied by fibers in a fiber bundle (SF), wall thickness and ratio of wall to lumen of fiber cell, and crystallinity of cellulose had an impact on the mechanical properties of LS fiber bundles. Furthermore, the fiber bundles density of LS varies range of 385.46-468.70 kg/m3, much less than that of jute (1360.40 kg/m3) and Arenga engleri (950.20 kg/m3) while LS fiber bundles has superior specific modulus.
Thu, 2 March 2017
ARTICLE Download: 718| View: 795| Comments: 0 | doi:10.20944/preprints201703.0019.v1
Subject: Materials Science, Biomaterials Keywords: anodic oxidation; titanium dioxide; electrolyte concentration; sulfuric acid
Online: 2 March 2017 (18:25:55 CET)
To obtain smooth coatings of TiO2 for building a new design of Ti-6Al-4V heart valve, the anodic oxidation technique in pre-spark conditions was evaluated. TiO2 coating is necessary for its recognize biocompatibility and corrosion resistance. A required feature on surfaces in contact with blood is a low level of roughness (Ra ≤ 50 nm) that not favor the formation of blood clots. The present paper compares the coatings obtained by anodic oxidation of the Ti-6Al-4V alloy using H2SO4 at different concentrations (0.1 M to 4 M) as electrolyte and applying different voltages (from 20 V to 70 V). Color and morphological analysis of coatings are performed using optical and scanning microscopy. The crystalline phases were analyzed by glancing X-ray diffraction. By varying the applied voltage different interference colors coatings were obtained. The differences in morphologies of the coatings, due to the change in concentration, are more evident at high voltages limiting the oxidation conditions for the desired application. Anatase phase was detected from 70 V for 1 M H2SO4. An increase in the concentration of H2SO4 decreases the voltage at which the transformation of amorphous to crystalline coatings occurs, i.e. with 4 M H2SO4 the anatase phase appears at 60 V.
Sat, 4 February 2017
ARTICLE Download: 1118| View: 1349| Comments: 0 | doi:10.20944/preprints201702.0010.v1
Subject: Materials Science, Biomaterials Keywords: amorphous polyphosphate microparticles; retinyl acetate; enamel cracks/fissures; Streptococcus mutans; human mesenchymal stem cells; collagen type I; alkaline phosphatase
Online: 4 February 2017 (07:37:55 CET)
Here we report the preparation and characterization of a novel biomimetic toothpaste containing morphogenetically active amorphous polyphosphate (polyP) microparticles enriched with retinyl acetate (“a-polyP/RA-MP”). The spherical microparticles (average size, 550±120 nm), prepared by co-precipitating sodium-polyP with calcium chloride and supplemented with retinyl acetate, were incorporated into a basis toothpaste at a final concentration of 1% or 10%. The paste containing “a-polyP/RA-MP” significantly increased the growth of human mesenchymal stem cells (MSC), compared to a commercial toothpaste which acts rather inhibitory and the paste without polyP and retinyl acetate. qRT-PCR experiments revealed that the retinoid causes an induction of the expression of the MSC marker genes for osteoblast differentiation encoding collagen type I and alkaline phosphatase. On the other hand, the polyP ingredient, supplied as Zn-polyP microparticles (“Zn-a-polyP-MP”) strongly inhibited the growth of the cariogenic bacterium Streptococcus mutans. We demonstrate that the amorphous polyP-containing toothpaste, enriched with retinyl acetate, efficiently repairs both cracks/fissures and carious lesions in the tooth enamel, and reseals dentinal tubules, already after a 5 d treatment (brushing) of teeth twice daily for 5 min as examined by SEM and quantitative EDX analysis. The stability of the occlusion of dentin cracks even turned out to resist against short high power sonication treatment. Our results demonstrate that the novel toothpaste prepared here, containing amorphous polyP and retinyl acetate, is particularly suitable for prevention/repair of (cariogenic) damages of tooth enamel/dentin and for treatment of dental hypersensitivity.
Wed, 30 November 2016
ARTICLE Download: 1287| View: 1093| Comments: 0 | doi:10.20944/preprints201611.0150.v1
Subject: Materials Science, Biomaterials Keywords: water-based polyurethane; hyaluronic acid; cartilage tissue engineering; scaffold
Online: 30 November 2016 (04:28:15 CET)
Diseases in articular cartilages have affected millions of people globally. Although the biochemical and cellular composition of articular cartilages is relatively simple, there is the limitation in self-repair ability of cartilage. Therefore, developing the strategies for cartilage repair is very important. Here, we reported a new manufacturing process of water-based polyurethane based photosensitive materials with hyaluronic acid and applied the materials for 3D printed customized cartilage scaffolds. The scaffold has high cytocompatibility and is one that closely mimics the mechanical properties of articular cartilages. It is suitable for culturing human Wharton's jelly mesenchymal stem cells (hWJMSCs) and the cells showed an excellent chondrogenic differentiation capacity. We consider that the 3D printing hybrid scaffolds may have potential in customized tissue engineering and facilitate the development of cartilage tissue engineering.
Fri, 11 November 2016
REVIEW Download: 1045| View: 1069| Comments: 0 | doi:10.20944/preprints201611.0060.v1
Subject: Materials Science, Biomaterials Keywords: cell-penetrating peptides (CPPs); reverse-transcriptase-subunit of telomerase (hTERT); GV1001; heat shock protein 90
Online: 11 November 2016 (09:59:30 CET)
Cell-penetrating peptides (CPPs), a group of small peptides capable of promoting the transport of molecular cargo across the plasma membrane, have become important tools in promoting the cellular uptake of exogenously delivered macromolecules. GV1001, a peptide derived from a reverse-transcriptase subunit of telomerase (hTERT) and developed as a vaccine against various cancers, reportedly has unexpected CPP properties. Unlike typical CPPs, such as the HIV-1 TAT peptide, GV1001 enabled the cytosolic delivery of macromolecules such as proteins, DNA and siRNA via extracellular heat shock protein 90 (eHSP90) and 70 (eHSP70) complexes. The eHSP-GV1001 interaction may have biological effects in addition to its cytosolic delivery function. GV1001 was originally designed as a MHC class II-binding cancer epitope, but its CPP properties may contribute to its strong anti-cancer immune response relative to other telomerase peptide-based vaccines. Cell signaling via eHSP-GV1001 binding may lead to unexpected biological effects, such as direct anticancer or antiviral effects. In this review, we focus on the CPP effects of GV1001 bound to eHSP90 and ehsp70.
Mon, 7 November 2016
ARTICLE Download: 1192| View: 1435| Comments: 0 | doi:10.20944/preprints201611.0038.v1
Subject: Materials Science, Biomaterials Keywords: polyhydroxybutyrate; nanofibrillated cellulose; paper coating; hydrophobicity
Online: 7 November 2016 (06:59:27 CET)
This study reports on the development of bio-based hydrophobic coatings for packaging papers through deposition of polyhydroxybutyrate (PHB) particles in combination with nanofibrillated cellulose (NFC) and plant wax. In a first approach, PHB particles in micrometer range (PHB-MP) were prepared through a phase-separation technique providing internally nanosized structures. The particles were transferred as a coating by dip-coating filter papers in the particle suspension, followed by sizing with a carnauba wax solution. This approach allowed partial to almost full surface coverage of PHB-MP over the paper surface resulting in static water contact angles of 105° to 122° and 129° to 144° after additional wax coating. In a second approach, PHB particles with submicron sizes (PHB-SP) were synthesized by an oil-in-emulsion (o/w) solvent evaporation method, and mixed in aqueous suspensions with 0 to 7 wt% NFC. After dip-coating filter papers in PHB-SP/NFC suspensions and sizing with a carnauba wax solution, static water contact angles of 112° to 152° were obtained. The intrinsic properties of the particles were analyzed by scanning electron microscopy, thermal analysis and infrared spectroscopy, indicating higher crystallinity for PHB-SP than PHB-MP. The chemical interactions between the more amorphous PHB-MP particles and paper fibers were identified as an esterification reaction, while the morphology of the NFC fibrillar network was playing a key role as binding agent in the retention of more crystalline PHB-SP at the paper surface, hence contributing to higher hydrophobicity.
Mon, 26 September 2016
REVIEW Download: 1553| View: 1102| Comments: 0 | doi:10.20944/preprints201609.0092.v1
Subject: Materials Science, Biomaterials Keywords: PMMA; bone cement; cardiac embolism; cement leakage; viscosity
Online: 26 September 2016 (10:34:26 CEST)
Percutaneous vertebroplasty procedure is of major importance, given the significant increasing aging population and higher number of orthopedic procedures related to vertebral compression fractures. Vertebroplasty is a complex technique involving injection of polymethylmethacrylate (PMMA) into the compressed vertebral body for mechanical stabilization of the fracture. Our understanding and ability to modify these mechanisms through alterations in cement material is rapidly evolving. However, the rate of cardiac complications secondary to PMMA injection and subsequent cement leakage has increased with time. The following review considers the main features of PMMA bone cement on the heart, and the extent of influence of materials on cardiac embolism. Clinically, cement leakage results in life-threatening cardiac injury. The convolution of this outcome through an appropriate balance of complex material properties is highlighted via clinical case report.
Fri, 19 August 2016
ARTICLE Download: 1270| View: 1025| Comments: 0 | doi:10.20944/preprints201608.0179.v1
Subject: Materials Science, Biomaterials Keywords: bioleaching; molecuar analysis; bacteria; sequencing; iron ore
Online: 19 August 2016 (09:23:04 CEST)
One consequence of the global technological advancement in conventional metallurgy is the fast depletion rate of valuable minerals, which are also becoming increasingly difficult to find in pure and economically viable forms. This has spurred more interest in technologies that investigate ability of different microorganisms to mobilize valuable metals from their ores via diverse metabolic processes. This study was carried out therefore to isolate, identify and characterize iron solubilizing bacteria from Iron stones of Agbaja iron ore mining site of Kogi State, Nigeria. Crushed samples in the range of 0.25µm and 0.75µm particle sizes were cultured in a modified 9k media to facilitate bacterial growth and pure cultures were then isolated and sub-cultured for further bioleaching studies. Morphological and biochemical analysis suggests that some of the bacteria identified are members of Acidithiobacillus spp, Pseudomonas spp, and Leptospirillum spp. Studies conducted on pure cultures and mixed consortium of the identified organisms shows that a mixture of the three organisms leached iron ore to about 96.16%. Also results of growth pattern due to bacteria countafter 24-72hours of incubation ranged between 0.1×103 cfu/ml and 12.3 ×103 cfu/ml for Acidithiobacillus spp. The need to explore the molecular characteristics of these organisms with a view to generating more information on the quality/quantity of their DNA for future cloning activities was also investigated in this work. DNA was extracted using zymo fungal/bacterial extraction mini prep kit TM (cat #6001) and subsequently subjected to 1% agarose gel electrophoresis. Visible bands were obtained with Alpha Innotech Gel Documentation Machine. DNA amplification was carried out using a pettier based thermo cycler PCR machine and electrophoresed on 1.5% agarose gel. Results of the PCR shows a visible band corresponding to 1.5kbp using this primer 27F (51-GAGTTTGATCCTGGCTCAG-31) and 1492R (51-GGTTACCTTGTTACGACT-31). DNA purity check shows two of the bacteria possess very good qualities for sequencing for further molecular analysis.