Search Results (162)

Silicone is widely used in medical devices due to its mechanical properties and biocompatibility; however, microbial contamination of silicone surfaces, which can lead to nosocomial infections, remains a significant concern. This can be countered by surface modification using techniques commonly involving oxidative plasma activation or ozone treatments, followed by treatment with silanization agents. Here, we report an alternative surface modification procedure involving treatment with non-toxic organic hydroxyl amines or diamine dissolved in eco-friendly solvents, thus avoiding using reactive and potentially harmful compounds and not requiring specialized equipment. Our findings demonstrate that ethanolamine in isopropanol effectively activates silicone without compromising its tensile strength, making it ideal for further modification. The activated surfaces showed stable amino group areal concentrations over a 10-day period, confirmed by fluorescence imaging and ninhydrin assays. Subsequent treatments with glutaraldehyde and chitosan enhanced the antibacterial properties of the silicone. Chitosan-coated silicone significantly reduced Gram-positive and Gram-negative bacteria colony-forming units (CFUs), with Enterococcus faecalis CFUs decreasing from 7.1 to 3.7 Log₁₀ CFU/mL. This study introduces a sustainable activation technique for silicone surfaces, resulting in medical devices with improved resistance to microbial colonization while maintaining their mechanical integrity. Full article

The scope of this work is the study of the evolution of Brettanomyces bruxellensis, the main wine spoilage yeast, during bottle fermentation of sparkling wines. Lambrusco (Emilia, Italy) was considered as a model wine, for its high concentration of precursors for B. bruxellensis activity, especially cinnamic acids. Five Lambrusco base wines furnished by a cooperative winery were inoculated with a 3-log concentration of B. bruxellensis and then underwent secondary fermentation in the bottle. Two strategies of contrast to B. bruxellensis, already successfully applied in red winemaking, were tested here for the first time in bottle fermentation: chitosan and a yeast proposed as a biocontrol agent. Bottle fermentation was monitored from a chemical and microbiological perspective. The resulting sparkling wines were analyzed by GC and HPLC–MS/MS to verify the presence of the key molecules indicating B. bruxellensis activity—biogenic amines, volatile phenols, and pyridines. Sensory analysis was also performed to establish the effects of the treatments on the overall wine profile. The results demonstrate that B. bruxellensis is capable of growing up to 5-log units, causing severe alterations of the wines, both from a chemical and sensorial point of view. The addition of chitosan at the beginning of bottle fermentation effectively mitigated the effects of B. bruxellensis, resulting in the wines being similar to the uncontaminated control. The effectiveness of the biocontrol agent under these conditions was lower and requires further investigation. Full article

This work presents the non-destructive assessment of polymeric composites based on synthetic matrices low-density polyethylene (LDPE) and polystyrene (PS) enhanced with chitosan (CS) biopolymer for use in active packaging systems for moisture control. Composites were prepared by incorporating CS at different contents (1, 3 and 5 phr) into LDPE and PS matrices. To evaluate the structural and thermal alterations induced by biopolymer loading, the materials were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The composites’ water-regulating properties—specifically, moisture absorption, retention, diffusion, and water vapor transmission rate—were quantitively tracked. Furthermore, the mechanical integrity of both dried and water-exposed systems was assessed via Shore D hardness testing. The results reveal a direct correlation between CS concentrations and enhanced hydrophilic behavior and water absorption, primarily attributed to the polar hydroxyl and amine groups within its molecular structure. The composites maintained adequate mechanical strength even after water exposure, confirming their structural stability for practical applications. This study demonstrates that the incorporation of CS into non-polar synthetic matrices significantly improves water affinity without requiring chemical compatibilizers, representing a cost-effective route to develop responsive packaging. The promise of these composites as responsive materials for real-time environmental interaction is highlighted by the successful non-destructive monitoring of their performance. This research establishes the feasibility and efficacy of non-destructive monitoring techniques in developing active packaging technologies, accelerating the progress of polymer-based systems with integrated and tunable moisture regulation capabilities. Full article

The proteolytic fraction (P1G10) from Vasconcellea pubescens displays pharmacological activity in diverse therapeutic settings. It is responsible for antifungal activity against Botrytis cinerea, impairing its germination and the integrity of the plasma membrane. The application of P1G10 is limited by stability in aqueous environments, where proteases lose activity. In this study, we aim to stabilize the proteolytic fraction, by complexation, to preserve the enzymatic activity ensued by controlled release. The proportion of each polymer, and the established reaction sequence, is chitosan (CS) plus P1G10 and alginate (ALG) using ALG:CS mass ratio = 1.0. Scanning electron microscopy (SEM) of the product shows the ALG-CS-P1G10 complex displaying a rough surface contrasting with the smoother surface of the ALG-CS complex, likely induced by interactions between the protein and ALG-CS complex. The optimal amount of protein taken up by the complex under this condition was 13 mg, and the incorporation yield was 72%. The melting temperature (Tm) determined by differential scanning calorimetry (DSC) in ALG-CS increased from 80 °C to 86 °C for the biocatalyst ALG-CS-P1G10; this difference was probably induced by the interactions between P1G10 and ALG-CS. Fourier transform infrared spectrometry (FTIR) comparison between ALG-CS and ALG-CS-P1G10 shows two bands in the biocatalyst at 1601 and 1523 cm⁻¹, suggesting the presence of amine residues from P1G10 which is rich in lysine residues. The release of P1G10 from the complex was assessed by increasing the ionic strength in the media between 0.1 and 0.4 M NaCl. The results show that, at 0.3 M NaCl, the protein released after 8 h attained 70% and expressed enzymatic activity of 0.90 × 10⁻³ U/mg protein compared to the enzymatic activity from free P1G10 protein, which was 5.55 × 10⁻⁴ U/mg protein. Full article

Functional hydrogels have significant potential for applications in the pharmaceutical, agricultural, and environmental sectors. This study focuses on the synthesis of polyampholytic hydrogels through free radical polymerization using functionalized chitosans. The chitosan was modified with mono and disulfonic groups at different temperatures (25 °C and 60 °C) and reaction times (1, 8, 24 h), followed by further modification with glycidyl methacrylate to introduce vinyl groups into the polymers structure. The modified polymers were analyzed using proton nuclear magnetic resonance, Fourier transform infrared, scanning electron spectroscopy, thermogravimetric analysis, and solubility tests. Specifically, 0.74 mmol/g and 1.58 mmol/g of the primary amine groups available in the chitosan chain (out of a total of 4.93 mmol/g) were substituted with mono- and disulfonic groups, respectively. Following treatment with glycidyl methacrylate, 3.39 mmol/g and 2.21 mmol/g of the remaining primary amine groups in the mono- and disulfonic polymers, respectively, were substituted. The hydrogels obtained by the modified polymers at optimal conditions of 1 h and 25 °C, were characterized by the techniques already mentioned in addition to rheological tests, and water absorption studies across different pHs. The hydrogels demonstrated potential for environmental remediation, particularly in adsorptions of ciprofloxacin (CPX) and copper (Cu²⁺) from aqueous solutions at pH 7, achieving adsorption efficiencies of 24–25% for CPX and 83% for Cu²⁺. The results suggest that the synthesized hydrogels could provide an eco-friendly and efficient solution to challenges in wastewater treatment. Full article

This study investigates the structural and functional enhancement of corn zein–chitosan composites via mild alkaline treatment to develop biodegradable protein-polysaccharide materials for diverse applications. Films with varying zein-to-chitosan ratios were fabricated and characterized using Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and scanning electron microscopy (SEM). Both untreated and sodium hydroxide (NaOH)-treated films were evaluated to assess changes in physicochemical properties. FTIR analysis revealed that NaOH treatment promoted deprotonation of chitosan’s amine groups, partial removal of ionic residues, and increased deacetylation, collectively enhancing hydrogen bonding and resulting in a denser molecular network. Simultaneously, partial unfolding of zein’s α-helical structures improved conformational flexibility and strengthened interactions with chitosan. These molecular-level changes led to improved thermal stability, reduced degradation, and the development of porous microstructures. Controlled NaOH treatment thus provides an effective strategy to tailor the physicochemical properties of zein–chitosan composite films, supporting their potential in sustainable food packaging, wound healing, and drug delivery applications. Full article

Background: In tissue engineering, developing injectable hydrogels with tailored mechanical and bioactive properties remains a challenge. This study introduces an injectable hydrogel composite for soft tissue regeneration, composed of oxidized alginate (OA) and N-succinyl chitosan (NSC) cross-linked via Schiff base reaction, reinforced with graphene oxide (GOx) and cyclic arginylglycylaspartic acid (c-RGD). The objective was to create a multifunctional platform combining injectability, bioactivity, and structural stability. Methods: The OA/NSC/GOx-cRGD hydrogel was synthesized through Schiff base cross-linking (aldehyde-amine reaction). Characterization included FTIR (C=N bond at 1650 cm⁻¹), Raman spectroscopy (D/G bands at 1338/1567 cm⁻¹), SEM (porous microstructure), and rheological analysis (shear-thinning behavior). In vitro assays assessed fibroblast viability (MTT) and macrophage TNF-α secretion (ELISA), while ex-vivo injectability and retention were evaluated using chicken cardiac tissue. Results: The hydrogel exhibited shear-thinning behavior (viscosity: 10 to <1 Pa·s) and elastic-dominated mechanics (G′ > G″), ensuring injectability. SEM revealed an interconnected porous structure mimicking native extracellular matrix. Fibroblast viability remained ≥95%, and TNF-α secretion in macrophages decreased by 80% (30 vs. 150 pg/μL in controls), demonstrating biocompatibility and anti-inflammatory effects. The hydrogel adhered stably to cardiac tissue without leakage. Conclusions: The OA/NSC/GOx-cRGD composite integrates injectability, bioactivity, and structural stability, offering a promising scaffold for tissue regeneration. Its modular design allows further functionalization with peptides or growth factors. Future work will focus on translational applications, including scalability and optimization for dynamic biological environments. Full article

This research explores the utilization of chitosan, a naturally derived biopolymer, as an innovative additive in bitumen for road construction. The experimental procedure for incorporating chitosan into bitumen, in agreement with its thermal stability, is described. Four different types of chitosan (two different degrees of deacetylation: >75 and >90% in free amine groups; molecular weight ranging from 100 to 800 kD) have been considered. Each chitosan was added to a bitumen at 1, 3, 6 wt%, and the mechanical characteristics were tested by dynamic shear rheology with the aim of testing the thermal stability of modified bitumen. An increase in the gel-to-sol temperature transition was generally found in the presence of chitosan, suggesting enhanced resistance to deformation under traffic loads. The most marked effect was obtained for chitosan with a molecular weight of 310,000–375,000 kD and with a deacetylation degree ≥75% (free amine groups). In addition, it was found that chitosan can slow down the oxidative aging of bitumen, especially when chitosan with high molecular weight (600,000–800,000 kD) and with a deacetylation degree >90% (free amine groups) was used. This further finding suggests that chitosan can potentially extend the final road pavement life. Full article

In this study, self-healing hydrogels were created using oxidized hydroxybutanoyl glycan (OHbG) and quaternized carboxymethyl chitosan (QCMCS), displaying antioxidant and antibacterial properties for pH-responsive drug delivery. The structures of the modified polysaccharides were confirmed through ¹H NMR analysis. Double crosslinking in the hydrogel occurred via imine bonds (between the aldehyde group of OHbG and the amine group of QCMCS) and ionic interactions (between the carboxyl group of OHbG and the quaternized group of QCMCS). The hydrogel exhibited self-healing properties and improved thermal stability with an increase in OHbG concentration. The OHbG/QCMCS hydrogel demonstrated high compressive strength, significant swelling, and large pore size. Drug release profiles varied between pH 2.0 (96.57%) and pH 7.4 (63.22%). Additionally, the hydrogel displayed antioxidant and antibacterial effects without compromising the polysaccharides’ inherent characteristics. No cytotoxicity was observed in any hydrogel samples. These findings indicate that the OHbG/QCMCS hydrogel is a biocompatible and stimuli-responsive drug carrier, with potential for various pharmaceutical, biomedical, and biotechnological applications. Full article

This study explores an innovative topical formulation to treat alopecia by encapsulating cannabidiol (CBD) in chitosan nanoparticles. CBD, widely known for its anti-inflammatory, antioxidant, and endocannabinoid-modulating effects, shows significant potential for treating alopecia, a condition characterized by hair loss influenced by genetic, hormonal, or environmental factors. However, its low water solubility presents a significant challenge for topical applications. To address this issue, chitosan nanoparticles were synthesized using chitosan of reduced molecular mass (270 kDa) with an acetylation level of 12%, β-glycerophosphate as a crosslinking agent, and 1% glycerol to improve CBD encapsulation efficiency. Physicochemical characterization using scanning electron microscopy (SEM), zeta potential measurement, and Fourier transform infrared spectroscopy (FTIR) revealed that the β-glycerophosphate concentration impacted nanoparticle size and the electrostatic interactions between chitosan’s primary amines and phosphate groups of β-glycerophosphate. Among the tested concentrations (0.05, 0.1, 0.2, and 0.25 mol/L), 0.20 mol/L produced the smallest nanoparticles (390 nm), which were further optimized to encapsulate CBD, reaching a particle size of 227 nm. This optimized formulation may improve the solubility of CBD and enable targeted and sustained delivery to hair follicles. These findings highlight chitosan nanoparticles as a cutting-edge and scalable platform for transdermal delivery of hydrophobic bioactive compounds, presenting a promising approach for the effective management of alopecia. Full article

Polybenzoxazines (PBzs), a class of high-performance thermosetting polymers, have gained significant attention for their exceptional thermal stability, mechanical properties, and chemical resistance, making them ideal for aerospace, electronics, and biomedical applications. Recent advancements emphasize their antimicrobial potential, attributed to unique structural properties and the ability to incorporate bio-active functional groups. This review highlights the synthesis, antimicrobial mechanisms, and applications of PBzs and their bio-based derivatives, focusing on sustainable materials science. PBzs demonstrate antimicrobial efficacy through mechanisms such as hydrophobic surface interactions and reactive functional group formation, preventing microbial adhesion and biofilm development. The incorporation of functional groups like amines, quaternary ammonium salts, and phenolic moieties disrupts microbial processes, enhancing antimicrobial action. Modifications with metal nanoparticles, organic agents, or natural bio-actives further augment these properties. Notable bio-based benzoxazines include derivatives synthesized from renewable resources like curcumin, vanillin, and eugenol, which exhibit substantial antimicrobial activity and environmental friendliness. Hybrid PBzs, combining natural polymers like chitosan or cellulose, have shown improved antimicrobial properties and mechanical performance. For instance, chitosan-PBz composites significantly inhibit microbial growth, while cellulose blends enhance film-forming capabilities and thermal stability. PBz nanocomposites, incorporating materials like silver nanoparticles, present advanced applications in biomedical and marine industries. Examples include zirconia-reinforced composites for dental restoration and urushiol-based PBzs for eco-friendly antifouling solutions. The ability to customize PBz properties through molecular design, combined with their inherent advantages such as flame retardancy, low water absorption, and excellent mechanical strength, positions them as versatile materials for diverse industrial and medical applications. This comprehensive review underscores the transformative potential of PBzs in addressing global challenges in antimicrobial material science, offering sustainable and multifunctional solutions for advanced applications. Full article

There are limited studies in the literature on the surface characterization of modified graphene and graphene oxide and the impact of these modified adsorbents on adsorption performance. In addition, the amine group essentially has a promising affinity for carbon dioxide (CO₂). Therefore, chitosan was used in this study to be grafted onto graphene and graphene oxide respectively. This study examines the effects of graphene, graphene oxide, and chitosan-modified graphene oxide thin films on the removal of carbon dioxide (CO₂). Thin films of graphene, graphene oxide, and their chitosan-modified counterparts were prepared via the methods of precipitation and grafting. The differences in the chemical structure, surface properties, and surface morphology of the films were evaluated, and their effect on the adsorption performance of CO₂ is discussed herein. The micrographs from a scanning electron microscope (SEM) show that the surface of graphene oxide appeared to be more porous than graphene, and the amount of grafted chitosan on graphene oxide is higher than that on graphene. An analysis of atomic force microscope (AFM) finds that the surface of chitosan-modified graphene oxide is rougher than that of chitosan-modified graphene. The results of energy-dispersive X-ray spectroscopy (EDS) spectra reveal that the composition of oxygen in graphene oxide is greater than that in graphene and confirm that the oxygen and nitrogen contents of chitosan-modified adsorbents are greater than those of the pristine materials. An analysis of Fourier-transform infrared spectroscopy (FTIR) shows that most of the oxygen-containing groups are reacted or covered by amide or amine groups due to modification with chitosan. The adsorption isotherms for CO₂ adsorbed by the prepared graphene and graphene oxide presented as type I, indicating great adsorption performance under low pressure. The appropriate amount of chitosan for modifying graphene oxide could be found based on the change in surface area. Although the breakthrough times and the thicknesses of the mass transfer regions for graphene oxide modified with 0.9% and 1.2% chitosan were similar, the modification of graphene oxide with 0.9% chitosan was appropriate in this study due to a significant decrease in surface area with 1.2% chitosan dosage. The adsorption uptake difference between chitosan-modified graphene oxide and graphene was greater than that without modification with chitosan due to more chitosan grafted on graphene oxide. The Toth adsorption isotherm model was used to fit the adsorption uptake, and the average deviation was about 1.36%. Full article

The efficacy of photodynamic therapy (PDT) based on traditional photosensitizers is generally limited by the cellular redox homeostasis system due to the reactive oxygen species (ROS) scavenging effect of glutathione (GSH). In this study, buthionine sulfoximine (BSO), a GSH inhibitor, was conjugated with the amine group of chitosan oligosaccharide (COS) using a thioketal linker (COSthBSO) to liberate BSO and chlorine e6 (Ce6) under oxidative stress, and then, Ce6-COSthBSO NP (Ce6-COSthBSO NP), fabricated by a dialysis procedure, showed an accelerated release rate of BSO and Ce6 by the addition of hydrogen peroxide, indicating that nanophotosensitizers have ROS sensitivity. In the in vitro cell culture study using HCT116 colon carcinoma cells, a combination of BSO and Ce6 efficiently suppressed the intracellular GSH and increased ROS production compared to the sole treatment of Ce6. In particular, Ce6-COSthBSO NP showed higher efficacy in the suppression of GSH levels and ROS production compared to the free Ce6 and Ce6/BSO combination. These results were due to the fact that Ce6-COSthBSO NP was efficiently delivered to the intracellular region, suppressed intracellular GSH levels, and elevated ROS levels. The in vivo animal tumor xenograft study demonstrated Ce6-COSthBSO NP being efficiently delivered to the tumor tissue, i.e., the fluorescence intensity in the tumor tissue was higher than those of other organs. The combination of Ce6 and BSO efficiently suppressed tumor growth compared to the sole treatment of Ce6, indicating that BSO might efficiently suppress GSH levels and increase ROS levels in the tumor microenvironment. Specifically, Ce6-COSthBSO NP showed the strongest performance in inhibition of tumor growth than those of Ce6 or the CE6/BSO combination, indicating that they were efficiently delivered to tumor tissue, increased ROS levels, and then efficiently inhibited tumor growth. We suggest that COSthBSO nanophotosensitizers are promising candidates for PDT treatment of cancer cells. Full article

The modification of polymers towards increasing their biocompatibility gathers the attention of scientists worldwide. Several strategies are used in this field, among which chemical post-polymerization modification has recently been the most explored. Particular attention revolves around polymer-L-cysteine (Cys) conjugates. Cys, a natural amino acid, contains reactive thiol, amine, and carboxyl moieties, allowing hydrogen bond formation and improved tissue adhesion when conjugated to polymers. Conjugation of Cys and its derivatives to polymers has been examined mostly for hyaluronic acid, chitosan, alginate, polyesters, polyurethanes, poly(ethylene glycol), poly(acrylic acid), polycarbophil, and carboxymethyl cellulose. It was shown that the conjugation of Cys and its derivatives to polymers significantly increased their tissue adhesion, particularly mucoadhesion, stability at physiological pH, drug encapsulation efficiency, drug release, and drug permeation. Conjugates were also non-toxic toward various cell lines. These properties make Cys conjugation a promising strategy for advancing polymer applications in drug delivery systems and tissue engineering. This review aims to provide an overview of these features and to present the conjugation of Cys and its derivatives as a modern and promising approach for enhancing polymer tissue adhesion and its application in the medical field. Full article

One major environmental issue responsible for water pollution is the presence of dyes in the aquatic environment as a result of human activity, particularly the textile industry. Chitosan–Polyvinylpolypyrrolidone (PVPP) polymer composite beads were synthesized and explored for the adsorption of dyes (Bismarck brown (BB), orange G (OG), brilliant blue G (BBG), and indigo carmine (IC)) from dye solution. The CS-PVPP beads demonstrated high removal efficiency of BB (87%), OG (58%), BBG (42%), and IC (49%). The beads demonstrated a reasonable surface area of 2.203 m²/g and were negatively charged in the applicable operating pH ranges. TGA analysis showed that the polymer composite can withstand decomposition up to 400 °C, proving high stability in harsh conditions. FTIR analysis highlighted the presence of N-H amine, O-H alcohol, and S=O sulfo groups responsible for electrostatic interaction and hydrogen bonding with the dye molecules. A shift in the FTIR bands was observed on N-H and C-N stretching for the beads after dye adsorption, implying that adsorption was facilitated by hydrogen bonding and Van der Waals forces of attraction between the hydroxyl, amine, and carbonyl groups on the surface of the beads and the dye molecules. An increase in pH increased the adsorption capacity of the beads for BB while decreasing OG, BBG, and IC due to their cationic and anionic nature, respectively. While an increase in temperature did not affect the adsorption capacity of OG and BBG, it significantly improved the removal of BB and IC from the dye solution and the adsorption was thermodynamically favoured, as demonstrated by the negative Gibbs free energy at all temperatures. Adsorption of dye mixtures followed the characteristic adsorption nature of the individual dyes. The beads show great potential for applications in the treatment of dye wastewater. Full article