Abstract: In recent years, many studies have pointed out the excellent properties of materials composed of collagen and chitosan for wound-healing applications. Combining both polymers in a wound dressing together with a bioactive compound could complement and potentiate these materials as new-generation wound-healing products. Hydroxytyrosol (HT), an antioxidant from olive oil, may contribute to wound healing due to its already reported anti-inflammatory, antimicrobial, and angiogenesis-stimulating properties. It could be a beneficial addition to collagen-chitosan dressings, improving their therapeutic effects. This study screens the potential of collagen-chitosan composites with HT for wound-healing applications and assesses the influence of the compound's incorporation on the materials' properties. The material production involved incorporating chitosan and HT into a marine collagen extract. The resulting collagen-chitosan-HT material was obtained by freeze-drying. Prototype dressing characterization included morphology by scanning electron microscopy, solid and hydrated state by textural and rheologic studies, and in vitro HT release studies. The materials’ cytocompatibility screening was assessed using a mouse fibroblast cell line, and the antibacterial activity was evaluated against microorganisms commonly implicated in wound infections. Results indicate that chitosan contributed to the material's mechanical robustness by maintaining a high viscosity and preserving the material gel structure. The in vitro release studies suggest an HT-controlled release profile with a maximum release (70%) achieved after 10 h. Biological experiments proved the materials' cytocompatibility with skin cells and very promising antibacterial efficacy against S. aureus and P. aeruginosa. In conclusion, HT was successfully incorporated into a collagen-chitosan matrix, enhancing the therapeutic prospect of the resultant material. The collagen-chitosan-HT composite presents a promising potential as an advanced wound-healing material.

Abstract: This study aims to develop high-performance biocomposites for structural applications using Kenaf, Bagasse, Hemp fibers and Softwood bonded with phenol-formaldehyde (PF) and phenol-urea-formaldehyde (PUF) resins commonly used in the industry for the production of the particleboard. A simple, low-cost fiber treatment was performed by adjusting the fiber pH from 5–6 to 11 and 13 using a 33% NaOH solution, following a standard protocol to improve fiber adhesion. PF and PUF adhesives were applied at a loading level of 13% (w/w), while polymeric diphenylmethane diisocyanate (pMDI) was used as a control adhesive at 5% (w/w) for untreated fibers. The fabricated panels were evaluated for mechanical properties, including modulus of elasticity (MOE), modulus of rupture (MOR), and internal bond strength (IB), as well as physical properties such as thickness swelling (TS) and water absorption (WA) after 24 hours of immersion. Bagasse at pH 11 exhibited the highest IB values with both PF and PUF, followed by Kenaf at pH 13, exceeding the EN 312:6 (2010) standard for heavy-duty load-bearing panels in dry conditions. The highest MOE and MOR values were obtained with Kenaf fibers at pH 11, meeting the EN 312:4 (2010) standard for load-bearing panels in dry conditions, followed by Bagasse, whereas Softwood and Hemp showed lower performance. In terms of thickness swelling, Bagasse demonstrated the best performance at all pH levels with both adhesives, followed by Kenaf and Hemp, outperforming the pMDI-based composites. The findings suggest that the high pH of the fibers creates an alkaline environment that boosts the reactivity of PF and PUF resins by enhancing the nucleophilic character of the phenolic rings during polymerization. Kenaf and Bagasse fibers can serve as viable alternatives to industrial softwood particles in EU panel production for structural applications. Furthermore, PF and PUF adhesives offer cost-effective alternatives to the more expensive and toxic pMDI. The observed performance variations among fibers are attributed to differences fiber structure (aspect ratio), and intrinsic properties, which influence their interactions with adhesives under varying pH conditions. The study suggested that Kenaf and Bagasse fibers could serve as promising raw materials for the production of medium-density homogeneous particleboards, with potential for structural application.

Abstract: Cobalt oxide nanoparticles (Co3O4 NPs) exhibit a variety of biomedical applications due to their special antioxidant, antibacterial, antifungal, anticancer, healing of wounds, and anti-diabetic characteristics. This work successfully prepared the Co3O4 NPs via simple galvanostatic deposition followed by annealing at 400 and 800oC for two hours. The galvanostatic deposition was carried out from a modified Watts bath. We used Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), energy dispersive X-ray (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM) to examine the oxide's characterization properties. The nature of the oxide formed was strongly dependent on the annealing temperature. The powder formed at room temperature (25oC) is a mixture of Co(OH)2 and metallic Co. However, at 400 and 800oC, and according to the XRD patterns, the powder is primarily composed of the Co3O4 phase and a slight quantity of Co(OH)2 phase. The average particle size measured by TEM ranged from 14.85 nm at room temperature to 90.19 nm at 800 oC. Moreover, the study examined how the operating deposition parameters affected the galvanostatic deposition process. Furthermore, these baths produce NPs, a great antibacterial agent that fights a variety of gram-positive and gram-negative bacteria, especially Staphylococcus aureus and Escherichia coli in addition to their effectiveness in terms of antifungal activity.

Abstract: Fossil gases account for more than one-third of all CO2 emissions caused by human activity. Previously, irreversible materials were used to capture CO2. Such sorbents cannot be reused, resulting in an increase in solid waste. For successful carbon sequestration, reversible sorbents are needed, yet very few examples of such sorbents are known. Chitin and Chitosan both have amino- groups with the potential to capture CO2 in an ‘acid-base’ reaction on the surface of the sorbent. In our study, CO2 sorption-desorption data for natural chitosan and its blends with pure and modified polysulfone has shown reversibility of the process and high sorption capacity. Blends show higher sorption capacity than pure chitosan, due to slower swelling in water, and slower loss of sorbent’s surface. Pure chitin derived from shells has a much lower sorption capacity than chitosan due to much higher molecular weight. Hydrolysis is required to convert chitin into an effective sorbent.

Abstract: Scar formation and delayed wound healing pose significant challenges in treating skin injuries, especially in severe cases like burns and diabetic wounds. This study investigates the effectiveness of novel Poly(vinyl alcohol) (PVA) / Gentamicin (Gent) and PVA / Chitosan (CHI) / Gent hydrogels in promoting healing of second-degree burn wounds in a rat model. Following in vitro testing, these hydrogels were deemed non-toxic and suitable for in vivo analysis. Clinical evaluations were conducted on 3rd, 7th, 14th and 21st post-injury day, assessing parameters such as blistering, edema, redness, crust, bleeding, secretion, scar tissue formation, and wound contraction percentage. Histological analyses focused on re-epithelization and dermal evaluation at specific time points. Results showed that both hydrogels significantly reduced inflammation, particularly redness, by the 14th day, and improved re-epithelization, with the PVA/CHI/Gent group outperforming on the 14th day and the PVA/Gent group excelling at the 21st day. Histological findings indicated increased fibroblast proliferation and collagen deposition in treated groups, suggesting enhanced dermal healing. The PVA/CHI/Gent hydrogel demonstrated notable antibacterial properties, likely due to the synergistic effects of CHI and Gent, leading to reduced inflammation and edema. Overall, both hydrogels show promise as effective wound dressings, facilitating faster healing and improved tissue recovery in burn injuries. This study supports the use of biomimetic scaffolds for enhanced wound management in clinical practices.

Abstract: Objective: This study aimed to evaluate the effects of different surface treatments—no treatment, sandblasting, hydrofluoric acid etching, and their combination—on the shear bond strength of 3D-printed composite resin discs bonded with Panavia V5 cement. Methods: 3D-printed composite resin discs received surface treatments and were bonded to Vita Mark II ceramic rods using Panavia V5 cement. Shear bond strength tests were conducted following 24-hour water storage at 37°C. Data were analyzed using one-way ANOVA and post-hoc Tukey tests (p < 0.05). Results: Hydrofluoric acid etching, alone or combined with sandblasting, significantly improved bond strength compared to no treatment (p < 0.01) and sandblasting alone (p < 0.05). The highest bond strength (40.73 ± 11.53 MPa) was found in the combination group, with no significant difference from hydrofluoric acid etching alone (p = 0.887). Conclusion: Hydrofluoric acid etching, with or without sandblasting, was the most effective surface treatment for enhancing bond strength in 3D-printed composite resins. Sandblasting alone showed no significant improvement compared to untreated surfaces.

Abstract: This work focuses on the design of polymeric systems that utilize hydrophilic polymers, with the primary aim of adapting these materials for biological applications. The study further evaluates the effectiveness of photoactive polymers in photodynamic therapy (PDT). It details the synthesis and characterization of photoactive copolymers derived from maleic anhydride (MAn) combined with vinyl monomers such as 2-methyl-2-butene (MB) and 1-octadecene (OD), as well as the organic compound 1-(2-hydroxyethyl)-3,3-dimethylindoline-6-nitrobenzopyran (SP). The two novel optically active alternating polymeric systems, poly(maleic anhydride-alt-octadecene) and poly(maleic anhydride-alt-2-methyl-2-butene), were functionalized with SP through an esterification process in a 1:1 monomer feed ratio, using pyridine as a catalyst. This methodology incorporated approximately 100% of the photoactive molecules into the main acrylic chain to prepare the alternating copolymers. These copolymers were characterized by UV-visible, FTIR, and 1H-NMR spectroscopy and optical and thermal properties. When exposed to UV light, the photoactive polymer films can develop a deep blue color (566 nm in the absorption spectra). Finally, the study also assesses their capacity for photodynamic antimicrobial action in organic film. Notably, the photoactive P(MAn-alt-2MB)-PS significantly enhances the photodynamic antimicrobial activity of the photosensitizer Ru(bpy) against two bacterial strains, reducing the minimum inhibitory concentration (MIC) from 2 µg/mL to 0.5 µg/mL. Therefore, 4 times less photosensitizer is required when mixed with the photoactive polymer to inhibit the growth of antibiotic-sensitive and resistant bacteria.

Abstract: In order to explore the thermal-storage stability of waterborne polyurethane (WPU) fabricated by prepolymer method, a series of WPUs were prepared with polyether polyol (PPG), aliphatic isocyanate (IPDI), dimethylol propionic acid (DMPA), 1, 4-butanediol (BDO), triethyl amine (TEA) and hydrazine hydrate (HyHy). Effects of NCO% of prepolymer, ratio of [NCO] to [H] after post-extension, HyHy dilution ratio and adding time, and solid content of WPU, were detailedly investigated. The viscosity and appearance of WPUs were used to characterize the stability during the thermal-storage process. Decreasing the NCO% of prepolymer, ratio of [NCO] to [H] after post-extension and solid content (SC) of WPUs, viscosity rise for WPUs in thermal-storage process decreased significantly; increasing the dilution ratio of H₂O to HyHy and prolonging the addition time of HyHy aqueous solution in the post-extension process, WPUs with stable viscosity under thermal-storage environment could be obtained. The mechanism for thermal-storage stability affected with “cage effect” was proved. The systematic study on the influencing factors and mechanism of thermal-storage stability in this study is of great significance to the understanding of prepolymer method and to promote the industrialization of WPUs via prepolymer method.

Abstract: The unique properties of insect silk have attracted attention for years to develop scaffolds for tissue engineering. Combining natural silks with synthetic polymers may benefit biocompatibility, mechanical strength, and elasticity. Silk-modified biomaterials are a promising choice for tissue engineering due to their versatility, biocompatibility, and many processing methods. In this study, the physicochemical and biological properties of biocomposites formed by combining caddisfly silk (Hydropsyche angustipennis) and polycaprolactone (PCL) were investigated. The PCL foams modified with caddisfly silk demonstrated full cytocompatibility and enhanced fibroblast adhesion and proliferation compared to unmodified PCL. These silk-modified PCL foams also induced NF-κB signalling, which is crucial for starting tissue regeneration. The antimicrobial properties of the silk-modified PCL foams remain comparable to PCL alone. The findings suggest that caddisfly silk-modified PCL foams present a promising solution for future medical and dental applications, emphasizing the potential of alternative silk sources in tissue engineering

Abstract: This work studied the extraction of bioactive metabolites from twelve Colombian marine macroalgae samples. Macroalgae samples were collected from the northeast coastal areas of Colombia and extracted using ultrasound-assisted liquid extraction with different Nades and compared them with reference solvents. The analysis of the extracts in-cludes preliminary chemical tests such as Folin-Ciocalteu quantifica-tion, DPPH assays, and MAAs identification using HPLC-DAD. In ad-dition, exploratory physicochemical tests measured the porosity of the sprayed material using the B.E.T. method and evaluated the Nades flow profile. HCl 5% extracts showed the highest yield of total phenolic compounds. It was 3-4% w/w for Gracilariopsis lemaneiformis, Hypnea sp., Pterocladiella capillacea, and Stypopodium zonale. Nades Beta-ine/Glucose/Water 1:1:5 had the highest efficiency extracting total phenolic compounds in most species. Over Sargassum polyceratium increasing the extraction scale, improved the recovery rate from 0 to 24 hours. The experiment reached saturation with 10 mL of BGluW115. It reproduced this result with different batches of glucose and betaine. MAAs concentrations ranged from 0.2 to 0.5 mg·g⁻¹ DW in the species analyzed with aqueous extractions. Nades FGW115 and BGW 115 allowed the detection of MAAs. Porosity differences among macroalgae did not affect phenolic recovery. Finally, Nades flow profiles exhibited Newtonian behavior.

Abstract: Titanium and its alloys as well as stainless steel are commonly used materials for implants in the human body due to their excellent biocompatibility, corrosion resistance and mechanical properties. However, the long-term performance of these implants in the oral cavity can be affected by the complex oral environment, including the ingestion of food, beverages and oral hygiene products, leading to the presence of various ions, pH fluctuations and inflammatory processes. Investigating the performance of AISI 316L stainless steel and Ti6Al4V alloy, two commonly used dental materials, in conditions that mimic inflammation can provide valuable insights into their suitability and long-term reliability and offer the opportunity to select the material according to the patient's health condition. The samples were exposed to artificial saliva with different concentrations of H2O2 with lactic acid for 24, 48, 72 and 96 hours. The study includes the potentiodynamic method, EIS, SEM and EDS analysis. The determined corrosion rates clearly show that Ti6Al4V has better corrosion properties at lower H2O2 concentrations, which decrease with increasing immersion time due to its excellent passivity ability, while AISI 316L is more corrosion resistant with increasing H2O2 concentration. Both samples also exhibit re-passivation after being exposed to a high concentration of H2O2 for 96 hours.

Abstract: The need for renewable and biodegradable materials for packaging applications has grown significantly in recent years. Growing environmental worries over the widespread using of synthetic and non-biodegradable polymeric packaging, particularly polyethylene linked to this increase in demand. This work focuses on the degradation of the low-de,nsity polyethylene LDPE properties which is basically widely used in the packaging, after adding different natural fillers, which is sustainable, compatible, and biodegradable natural polymers .The LDPE was mixed with (2.5, 5, and 10) wt% of each (sawdust, powder cellulose, and Nano crystalline cellulose CNC). The composites melted and mixed using a twin-screw extruder machine with a screw speed of 50 rpm at 190 C, to produce sheets through a specific die. These sheets used to prepare samples for rheological test through viscosity curve, flow curve and non-Newtonian mathematical model using capillary rheometer at 170, 190,and 210oC. X-ray diffraction and degradation tests at short period carried out in soil with a pH of 6.5 and 50% humidity at 27°C. The results showed that the composites melts were non-Newtonian and the shear thinning behavior dominant during viscosity curves. The shear viscosity increases with the different cellulose additives increasing. The 5% ratio indicated higher viscosity for all composites melts and the LDPE\CNC melts showed higher viscosity at different temperatures. The curve fitting was proved that the suitable model for all flows of the composites melts was power law .The LDPE\ sawdust and powder cellulose melts showed higher flow index n and lower viscosity consistency k compared with the LDPE\CNC melt at different temperatures. The sawdust and powder composites indicate higher weight loss compared with the CNC/LDPE composites, these results supported by digital images after 30 day. The degradation test and weight loss illustrate stronger relation with the viscosity values at low shear rate. The higher the shear viscosity the lower the degradation and vice versa.

Abstract: Hydrogels are promising materials for biomedical applications due to their tunable properties. Despite significant research on optimizing the mechanical and rheological properties of chitosan hydrogels, a comprehensive analysis incorporating pH and molarity of the neutralizing solution is still lacking. This study addresses this gap by evaluating how these factors influence rheological characteristics of chitosan hydrogels. The hydrogels were prepared using an acidic blend and were neutralized with sodium hydroxide solutions. Rheological characterization demonstrated that all samples exhibited pseudoplastic behavior, with viscosity decreasing under shear stress. Higher pH values’ hydrogels showed reduced viscosity, linked to decreased protonation and electrostatic repulsion between chitosan chains, while more acidic conditions led to higher viscosity and entanglements. NaOH concentration impacted gel stability; lower concentrations resulted in more stable gels, whereas higher concentrations increased crosslinking but compromised integrity at elevated pH. These findings are critical for designing chitosan hydrogels with tailored properties for targeted biomedical uses.

Abstract:

Nanomaterials have revolutionized various biological applications, including cosmeceuticals, enabling the development of smart nanocarriers for enhanced skin delivery. This review focuses on the role of nanotechnologies in skincare and treatments, providing a concise overview of smart nanocarriers, including thermo-, pH-, and multi-stimuli sensitive systems, focusing on their design, fabrication, and applications in cosmeceuticals. These nanocarriers offer controlled release of active ingredients, addressing challenges like poor skin penetration and ingredient instability. This work discusses the unique properties and advantages of various nanocarrier types, highlighting their potential in addressing diverse skin concerns. Furthermore, we address the critical aspect of biocompatibility, examining potential health risks associated with nanomaterials. Finally, this review highlights current challenges, including precise control of drug release, scalability, and the transition from in vitro to in vivo applications. We also discuss future perspectives, such as the integration of digital technologies and artificial intelligence for personalized skincare to further advance in the technology of smart nanocarriers in cosmeceuticals.

Abstract: Shear-Thickening or dilatant behavior is difficult to observe because it is frequently confused with mechanical oscillation or with experimental deviation. In appropriated shear rate range this behavior can be identified in samples that behave as a pseudo-plastic or Newtonian fluid in large shear rate range, evidencing what is currently called the shear-thickening – shear-thinning transition, ST–ST transition, even though this transition is less common than the shear-thinning – shear-thickening transition, in which dilatancy occurs at considerably higher shear rates. Chitosan hydrogels have gained significant attention due to their potential applications in various fields, in-cluding biomedical engineering, drug delivery, and tissue regeneration. These hydro-gels due to its peculiar structure often exhibit ST-ST behavior if the shear rate applied is low enough that this transition can be observed. In this work, chitosan hydrogels obtained from chitosan with different molar masses, degrees of acetylation, degree of crosslinking, preparation methods and aging conditions prior to rheological tests at shear rates between 0.03 s-1 and 1.5 s-1, at temperatures of 22°C, 23°C and 37°C were analyzed and the ST-ST transition related to these parameters. It was found that the ST-ST transition is more influenced by pH, molarity and chitosan concentration than by thermal aging.

Abstract: Cosmetic formulations are complex mixtures of ingredients that must fulfil several requirements. One of the challenges of the cosmetic industries is to find natural alter-natives to replace synthetic polymers, preserving desirable sensory characteristics. The aim of this work is to induce the formation of gels, by replacing synthetic polymers with a low-molecular-weight gelator (LMWG), a small molecule able to self-assemble and to form supramolecular networks. The impact on environment of low-molecular-weight gelators is much reduced, as they are highly biodegradable. Thus the behaviour of so-lutions containing Boc-L-Dopa(Bn)2-OH, a LMWG, together with ten different anionic surfactants was studied, to understand if the LMWG may act as rheological modifier by increasing the viscosity of the formulation or forming gels with these ingredients. In most cases, the addition of the gelator in only 1% w/v concentration induces the gelifi-cation of the solutions, thus showing that this molecule is able to self-assemble also in complex mixture. An amphoteric surfactant, cocamidopropyl betaine (CABP), often used to increase cleansing gentleness, was also added to the solutions to better mimic a cosmetic formulation. These samples form gels, thus showing that the CABP addition does not disturb their formation.

Abstract: This study presents a novel biosensor for non-invasive glucose detection in saliva, using sol colloids with erbium phthalocyanine and polyvinyl acetate particles. Erbium phthalocyanine, a green, fluorescent pigment synthesized with a solar reactor, was characterized using various techniques, confirming its successful preparation. Thin films of erbium phthalocyanine in polyvinyl acetate colloids were deposited on glass substrates to manufacture the sensors. These films were characterized by ultraviolet-visible spectroscopy, revealing distinctive absorption bands. The biosensors effectively detected glucose in saliva from individuals with different health conditions. The study demonstrates the potential of these biosensors as practical and non-invasive tools for glucose monitoring, contributing to non-invasive diabetes monitoring technologies. The findings suggest that organic semiconductors, particularly erbium phthalocyanine, are significant in biosensor development, promising improved early detection and management of diabetes.

Abstract: Chitosan is an attractive material for developing inks for extrusion-based bioprinting of three-dimensional structures owing to its excellent properties, including its mechanical properties and antimicrobial activity when used in wound dressings. A key challenge in formulating chitosan-based inks is to improve its gelation property to ensure reliable printing and the mechanical stability of the printed structures. To address these challenges, this article presents a novel chitosan/oxidized glucomannan composite hydrogel that combines Schiff base and phenol crosslinking reactions. The proposed biomaterial forms soft hydrogels through Schiff base crosslinking, which can be further stabilized via visible light-induced phenol crosslinking. This dual-crosslinking approach enhances the printability and robustness of chitosan-based ink materials. The proposed chitosan/oxidized glucomannan hydrogel exhibits excellent extrudability and improved shape retention after extrusion, along with antimicrobial properties against Escherichia coli. Moreover, good cytocompatibility was confirmed in animal cell studies using mouse fibroblast 10T1/2 cells. These favorable features make this hydrogel highly promising for the extrusion-based bioprinting of complex 3D structures, such as tubes and nose-like structures, at a low crosslinker concentration and can expand the prospects of chitosan in bioprinting, providing a safer and more efficient alternative for tissue engineering and other biomedical applications.

Abstract: Membranes made from biopolymers and loaded with doxycycline were investigated for potential use in the treatment of foot ulcers in diabetic patients. Carboxymethylcellulose (CMC) and chitosan (CHS) membranes were fabricated with 7% glycerol and 1% doxycy-cline (DOX). The mechanical and physical properties, biocompatibility, and antimicrobial effects were thoroughly evaluated. The results demonstrated effective antibacterial activity against S. aureus and S. mutans. Based on the mechanical, physical, and hemolytic data, DOX-loaded CMC/CHS/G membranes show promise as a topical wound delivery system.

Abstract: Due to the problematic export of black pepper, such as microbiological contaminants, the objective was to develop biodegradable films as a protective film on the seeds. Film-forming solutions (FFS) for coating and cassava starch (CS) and starch and xylitol (CX) films were produced. The technological properties were performed on the films: thickness, water vapor permeability (WVP), solubility, tensile strength (TS), and elongation (%). To monitor the efficiency of the coating, the shelf life of the control (CP- uncoated) and coated (RP) peppers was evaluated regarding moisture (%), water activity (aw), mass loss (ML%), apparent and real specific mass (g/ml), porosity (%), weight of a thousand seeds (g), color analysis and microbiological analysis. The CX film showed no difference (p ≤ 0.05) in thickness, and presented higher values (p ≤ 0.05) of WVP, solubility, and elongation (%) compared to the CS film. The peppers presented a microbiological standard established by current legislation. The RP presented lower (p ≤ 0.05) moisture gain and aw, lower porosity values, thousand seed weight, and ML (%) compared to the CP, demonstrating the positive contribution of the starch and xylitol film in the coating process.