Search Results (1,136)

In this work, the effect of chitosan concentration in chitosan/nickel composite coatings on their morphology and electrocatalytic activity in hydrogen evolution reaction (HER) was investigated. A series of Chitosan/Ni coatings with chitosan content from 0 to 0.7 wt.% was obtained by nickel electrodeposition onto a preformed biopolymer matrix, enabling targeted control of the roughness and specific surface area of the nickel layers. Morphology and roughness parameters were studied using atomic force microscopy and confocal microscopy. Electrochemical activity in the HER was examined by linear sweep voltammetry. Among the studied electrocatalysts, the Chitosan(0.6)/Ni system showed the best HER efficiency, with an overpotential of −200 mV at a current density of 10 mA/cm². Electrochemical impedance spectroscopy was used to determine the real surface area of the coatings. The Chitosan(0.6)/Ni sample exhibited the largest surface area, explaining its high HER activity. The obtained data revealed a correlation between chitosan concentration, composite morphology, and electrochemical activity, and allowed determination of the optimal composite composition. The results demonstrate the potential of chitosan as an effective structural modifier of nickel coatings and open up possibilities for the targeted design of composite materials with tailored electrochemical properties. Full article

This study investigates the damage behavior and surface integrity of chitosan–nanohydroxyapatite (CS/nHAp) composite coatings, along with their corrosion resistance and wettability, which directly affect their biological performance in vivo. The coatings were deposited on Ti13Zr13Nb and stainless steel using electrophoretic deposition (EPD) at various voltages and deposition times. Surface topography, morphology, composition, and roughness were characterized using microscopic techniques, while wettability, corrosion resistance, and mechanical properties were assessed. Three-point bending tests were performed to determine coating behavior under mechanical deformation. Hydrophilic, homogeneous CS/nHAp coatings were successfully deposited without visible cracks on the surface. Coatings deposited at 10 V exhibited higher corrosion potentials compared to uncoated titanium alloy. Mechanical testing showed that coatings deposited at 10 V were significantly harder than those deposited at 20 V. The CS/nHAp20_5 coating exhibited moderate hardness (0.33 ± 0.06 GPa), the lowest Young’s modulus (12.7 ± 1.4 GPa), increased flexibility, and good adhesion, without delamination during bending tests. These results demonstrate that by modifying deposition parameters, it is possible to adjust the mechanical and protective properties of CS/nHAp coatings for potential application of the developed coating in vascular stents. Full article

Penaeus sp. shells (shrimp) were used to extract chitosan using acid and basic treatments, which were characterized by IR spectroscopy, Raman spectroscopy, potentiometric titration, and elemental analysis. The degrees of deacetylation were determined to be 71.8%, 75.6%, 53.4%, and 68.6%, respectively. Likewise, viscosimetry measurements were carried out, determining an average molecular weight of chitosan 1 of 1521467.919 (g/mol). The obtained chitosan was used as a substrate in condensation reactions with 10 para-substituted benzaldehydes. The products obtained were characterized by IR, Raman, and ¹H-NMR spectroscopy, AE (Elemental Analysis), TGA (Thermogravimetric Analysis), and DSC (Differential Scanning Calorimetry). For the obtained polymers, biological assays of cytotoxicity using RAW macrophage cells and leishmanicidal activity on promastigotes of Leishmania mexicana were performed. The results show that the synthesized products do not present in vitro cytotoxicity, and that 1 (Chitosan) and 3i (Schiff Base) present leishmanicidal activity. Selected derivatives were incorporated into polyvinyl alcohol-based films and evaluated for surface topography and gas permeability. AFM revealed nanometric roughness patterns, while gas exchange studies demonstrated selective CO₂/O₂ permeability, supporting passive modified atmosphere formation in packaged carrots. Mechanical characterization revealed that the incorporation of Schiff base derivatives significantly influences tensile strength and flexibility, with certain films exhibiting enhanced elongation and mechanical performance compared to pure PVA, highlighting their potential for packaging applications. These findings confirm that chemical functionalization enhances the versatility of chitosan, allowing the design of tailored biopolymers. The synthesized derivatives show promising characteristics for the development of biodegradable films with potential applications in food packaging and antiparasitic material development. Full article

Gymnema lactiferum (G. lactiferum) is a medicinal plant that contains potent bioactive phytochemicals, which are prone to degradation during processing and digestion. In this study, G. lactiferum extract was prepared and encapsulated into soy lecithin primary liposomes (PL) and then coated with chitosan to form secondary liposomes (chitosomes, CS) to enhance stability. Physicochemical characteristics, morphology, thermal behavior, and storage stability were evaluated. Extract loading significantly (p < 0.05) increased the mean diameter of PL from 128.6 nm to 146.3 nm and of CS from 359.1 nm to 408.9 nm compared with unloaded liposomes. Both liposomal systems exhibited homogeneous size distributions and good colloidal stability, with zeta potentials of −39.4 mV for PL and +35.8 mV for CS and low polydispersity indices (<0.25) for both systems. Transmission electron microscopy demonstrated predominantly spherical morphologies in both systems. Chitosan coating significantly (p < 0.05) improved both encapsulation efficiency (77.3%) and encapsulation yield (82.4%) compared with PL (73.7% and 79.1%, respectively). HPLC-based quantification using rutin as a reference analyte further indicated EE-R% values of 59.8% for PL-GE and 70.3% for CS-GE, supporting improved extract retention following chitosan coating. Fourier transform infrared spectroscopy confirmed successful encapsulation without apparent chemical alterations or reactions. Differential scanning calorimetry indicated that chitosan coating modified the thermal transition behavior of the liposomal membrane, consistent with altered bilayer packing and increased membrane fluidity, while incorporation of the extract partially restored thermal order within the coated system. Overall, chitosan coating effectively enhanced the encapsulation efficiency, stability, and yield of G. lactiferum extract-loaded liposomes towards their incorporation into functional food formulations. Full article

Waterborne polyurethane (WPU) is widely used in flexible films and textile finishing, but its intrinsic flammability, severe melt dripping, and sensitivity to polar additives restrict its fire-safe applications. Herein, a phosphorous acid-protonated chitosan (PCS) was designed as an emulsion-adaptable bio-based modifier and incorporated into cationic WPU via a facile aqueous blending route, yielding transparent multifunctional composite films and flame-retardant textile coatings. Unlike conventional flame-retardant WPU systems that rely on reactive monomers or suffer from poor emulsion compatibility, this work proposes an emulsion-compatible strategy based on PCS, enabling the simultaneous integration of dispersion stability, flame retardancy, and antibacterial functionality within a single system. PCS could be stably accommodated in the WPU latex without visible precipitation or demulsification after centrifugation, and the resulting films preserved a continuous matrix structure with uniformly distributed PCS-rich nanodomains. Rheological analyses revealed that the polar groups of PCS established strong intermolecular associations with urethane segments, strengthening the physical network. The char residue at 700 °C increased from 0.7 wt% for neat WPU to 32.7 wt% for WPU/PCS-5. Meanwhile, WPU/PCS-5 achieved a limiting oxygen index of 35.4% and a UL-94 V-0 rating, while its peak heat release rate and total heat release were reduced by 73.4% and 41.8%, respectively. The composite films also showed nearly complete antibacterial efficiency against Escherichia coli and Staphylococcus aureus. As a textile coating, WPU/PCS-5 enabled immediate self-extinguishing of cotton fabric, increased the limiting oxygen index from 18.5% to 27.2%, and reduced the damaged length from 30.0 to 11.0 cm. This work demonstrates that an emulsion-compatible strategy based on PCS can effectively integrate dispersion stability, fire safety, multifunctionality, and coating applicability into WPU materials. Full article

Background: Intrauterine adhesions, a leading cause of female infertility, frequently recur in 30–62.5% of patients despite hysteroscopic adhesiolysis and adjuvant therapies. Current intrauterine barriers, including injectable hydrogels, often lack sufficient bioactivity and tissue retention, failing to address the underlying pathological inflammation and oxidative stress driving abnormal fibrosis. Methods: Herein, we tailored a reactive oxygen species (ROS)-responsive, mussel-inspired adhesive injectable hydrogel (OHA-CP@TA) to intelligently modulate the inflammatory niche and promote normal endometrial regeneration. OHA-CP@TA was fabricated through Schiff base bonds between oxidized hyaluronic acid (OHA) and phenylboronic acid-modified carboxymethyl chitosan (CMCS-PBA), and boronate ester bonds between CMCS-PBA and tannic acid (TA). Results: OHA-CP@TA exhibited good mechanical strength, injectability, self-healing, and shear-thinning properties, and importantly, robust and stable adhesion to uterine tissue, overcoming endometrial mucus clearance. It also showed favorable in vivo uterine cavity retention for at least 7 days that covered the critical endometrial repair period. Within the postoperative inflammatory milieu, OHA-CP@TA intelligently released TA in a ROS-dependent manner, which effectively scavenged various ROS and significantly alleviated inflammation, and promoted M1 macrophage polarization into M2 phenotype. This targeted ROS scavenging and immunoregulation inhibited endometrium fibrosis progression, evidenced by downregulation of α-SMA and Col-1, and actively promoted endometrial repair and regeneration, demonstrated by enhanced angiogenesis, increased endometrial thickness, and restoration of glandular numbers. Furthermore, OHA-CP@TA exhibited good biocompatibility, in vivo biodegradability and safety. Conclusions: Therefore, OHA-CP@TA represents a promising, clinically translatable strategy for overcoming the limitations of current IUA management. Full article

Background: Avian influenza is a critical zoonotic infection threatening both the poultry industry and global public health. While traditional intramuscular vaccines elicit systemic immunity, they often fail to provide robust local protection at mucosal surfaces. There is thus significant interest in the development of mucosal avian influenza vaccines administered via the intranasal route. However, in humans, this approach is significantly hampered by the availability of safe and effective adjuvants. Methods: This study investigated the immunogenicity of a modified recombinant influenza A/H5 hemagglutinin (rHA/H5-modif) formulated with Novochizol, a novel chitosan-derived delivery system, administered intranasally to laboratory animals. Results: Our results demonstrate that mucosal immunization with the rHA/H5-modif/Novochizol complex induces potent humoral (IgG and IgA) and cell-mediated immune responses. Crucially, the formulation provided 100% survival in mice following a lethal challenge with highly pathogenic avian influenza A/H5. Conclusions: These findings position the rHA/H5-modif/Novochizol complex as a promising candidate for next-generation mucosal vaccines, in particular against highly pathogenic avian influenza A/H5 subtype. Full article

This study investigates lignin as a renewable functional dye capable of simultaneously imparting coloration and multifunctional performance to cotton textiles, with particular emphasis on how chitosan polymorphs influence lignin-mediated silver nanoparticle (AgNP) systems. Cotton fabrics were pretreated with α- or β-chitosan crosslinked with glyoxal and subsequently dyed with lignin in the presence of silver ions to generate lignin-mediated AgNPs. Inductively coupled plasma optical emission spectrometry (ICP–OES) analysis showed that α-chitosan retained a higher silver content (40.7 mg/kg) than β-chitosan (14.7 mg/kg). Transmission electron microscopy (TEM) revealed that α-chitosan produced larger AgNPs (≈13.6 nm), whereas β-chitosan was associated with smaller measurable nanoparticles (≈4.3 nm). Despite lower silver loading, β-chitosan–modified fabrics exhibited higher antibacterial activity against Staphylococcus aureus (82.6%) than α-chitosan-modified fabrics (68.7%). These results suggest that antibacterial performance in lignin–silver coating systems may depend not only on silver loading, but also on the distribution and accessibility of active components within the coating layer. In addition, the coatings improved UV protection, tensile properties, and color strength. Overall, the findings demonstrate that chitosan polymorphism plays an important role in controlling nanoparticle characteristics and multifunctional performance in lignin-based textile systems. Full article

C-reactive protein (CRP) is one of the most essential biomarkers for the early detection of inflammation and infection. In this study, we developed a sensitive and selective electrochemical immunosensor for CRP detection, leveraging the unique properties of gold nanoparticles (AuNPs). A nanostructured layer of AuNPs was deposited onto a screen-printed carbon electrode (SPCE), followed by the formation of a self-assembled monolayer (SAM) of L-cysteine and EDC/sulfo-NHS chemistry. The antibody was covalently immobilized onto the modified electrode through optimized dual-crosslinking chemistry. Detection conditions were systematically optimized, with pH 8.0 in Tris buffer providing the best electrochemical response. Electrochemical characterization was performed using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV) in a 5 mM K₃[Fe(CN)₆]/K₄[Fe(CN)₆] redox probe solution containing 0.1 M KCl. CRP detection was achieved by monitoring the increase in charge transfer resistance (Rct) upon specific binding of the target CRP antigen to the immobilized antibody. Spiked recovery experiments showed spiked recovery rates ranging from 98.01% to 107.14%, with a standard deviation below 4%. Regeneration studies demonstrated high efficiency, confirming the suitability of the sensor interface for repeated and reliable measurements. Under optimized conditions, the immunosensor exhibited excellent analytical performance, including a low limit of detection (LOD) of 0.16 µg/mL, a wide linear detection range of 5–100 µg/mL, high selectivity against 13 potential interferents (including inflammatory cytokines), and good reproducibility with a relative standard deviation (RSD) of 3.69%. The sensor also showed strong stability, retaining more than 95% of its signal after 15 days, and high regeneration efficiency of 97% over seven cycles. These results highlight the strong potential of the proposed immunosensor for point-of-care (POC) applications due to its simple fabrication, cost-effectiveness, user accessibility, and robust analytical performance. Full article

Erythrosine B (ER) dye is widely used and increasingly detected in wastewater, necessitating effective removal. This study compares chitosan beads (CB) and chemically crosslinked beads, namely chitosan–tripolyphosphate (CT) and chitosan–sulphite (CS), for ER removal via batch adsorption studies. Characterisation confirmed successful crosslinking of the modified beads. Under optimised conditions, CB, CT, and CS achieved removal efficiencies of 75.27%, 91.69%, and 98.73%, respectively, at an initial concentration of 100 mg/L within 50–60 min. Kinetic analysis suggested that the rate-controlling step was not solely governed by intraparticle diffusion but also involved physisorption and chemisorption. While the Langmuir isotherm adequately described the adsorption process of CB and CT, with maximum adsorption capacities of 71.80 mg/g and 89.33 mg/g, respectively, a better fit was observed for the Freundlich and Redlich–Peterson isotherms, indicating multilayer adsorption. In contrast, CS showed moderate agreement with all isotherms, suggesting a complex removal process. CS demonstrated the highest adsorption capacity, with 120.30 mg/g, highlighting sodium metabisulphite (SM) as a promising crosslinking agent for improved dye removal. Density functional theory (DFT) analysis proposed that at the molecular level, interactions between the ionised oxygenated groups of ER and protonated amine groups of chitosan facilitated the adsorption process. Full article

Chitosan (CS) was employed to modify coconut shell activated carbon (CAC) to fabricate a composite adsorbent for wastewater treatment. By integrating the functional groups of CS with the high specific surface area of CAC through chemical modification, the resulting CS-AC composite exhibited significantly enhanced adsorption performance toward hexavalent chromium (Cr(VI)) in aqueous solutions. The effects of key parameters, including adsorbent dosage, initial Cr(VI) concentration, contact time, temperature, and solution pH on the adsorption efficiency were systematically investigated. Under optimal conditions, the CS-AC composite achieved a Cr(VI) removal efficiency of up to 99.04%. Kinetic and isotherm modeling revealed that the adsorption process followed the pseudo-second-order kinetic model and was well described by the Langmuir isotherm. Regeneration studies conducted over five consecutive adsorption-desorption cycles demonstrated that the composite retained a high removal efficiency of 98.10%, indicating excellent reusability. These findings suggest that the CS-AC composite is a promising and effective adsorbent for the removal of Cr(VI) from contaminated water. Full article

Proton exchange membrane fuel cells (PEMFCs) are among the most promising clean energy conversion technologies, offering high efficiency and zero emissions. However, their large-scale commercialisation is limited by the high cost and environmental impact of conventional perfluorosulfonic acid membranes such as Nafion. In recent years, increasing attention has been directed toward biopolymer-based membranes as sustainable, low-cost, and biodegradable alternatives. This review provides a comprehensive overview of recent advances in the development and modification of biopolymer membranes, including polysaccharide-based materials such as chitosan, cellulose, gellan gum, sodium alginate, and starch, as well as protein-based materials such as keratin and collagen. Various modification strategies, including sulfonation, phosphorylation, cross-linking, and incorporation of inorganic or hybrid fillers, are analysed for their impact on key parameters, including proton conductivity, methanol permeability, and power density. Comparative data indicate that several modified biopolymer membranes achieve proton conductivities of 50 mS/cm or higher. However, higher conductivity values are generally reported for membranes primarily composed of synthetic polymers, where the biopolymer is incorporated only as an additive. In addition, some biopolymer-based membranes exhibit significantly lower methanol permeability than Nafion. The lowest reported value among the membranes discussed in this article is 0.98 × 10⁻¹⁶, representing the best-performing biopolymer membrane in terms of methanol permeability alone. Although many biopolymer membranes demonstrate relatively poor performance in single PEMFC tests, several have achieved power densities comparable to Nafion, while simultaneously offering improved environmental compatibility and sustainability. Finally, current challenges and future directions are discussed, emphasising the potential of these renewable materials to advance PEMFC technology toward more sustainable and economically viable energy systems. Full article

Tissue engineering represents a central strategy in regenerative medicine to restore damaged or missing tissue through structural and functional replacement. In this study, a two-component bioink platform was developed based on amine–anhydride conjugation as a mild crosslinking reaction between synthetic anhydride-containing oligomers (oSMoMA-x) and natural biopolymers. The compatibility of the oligomers with different amine-containing biopolymers, including chitosan, gelatin, and hydrolyzed collagen peptides, was systematically evaluated. To improve cytocompatibility and enable controlled network formation, oSMoMA oligomers with varying anhydride contents were synthesized and characterized, allowing targeted tuning of material properties through comonomer composition. The resulting hydrogels were comparatively assessed with respect to their rheological and physicochemical properties. While hydrogel formation was achieved with all investigated biopolymers, gelatin-based systems exhibited the most favorable characteristics for bioink development. Two gelatin/oSMoMA bioink formulations with distinct gelation behavior were obtained by employing different base catalysts, enabling control over crosslinking kinetics and material properties. Cytocompatibility was comprehensively evaluated using viability assays, demonstrating enhanced metabolic activity of cells encapsulated in gelatin/oSMoMA-3.5 hydrogels compared to established reference systems, with sustained compatibility for up to seven days. Extrusion-based 3D bioprinting was performed using a modified printhead with integrated temperature control to maintain physiological conditions. The bioinks were successfully printed with embedded murine 3T3 fibroblasts, and post-printing analyses confirmed cell proliferation within the hydrogel constructs. Overall, the results demonstrate the broad compatibility of amin–anhydride-crosslinked oSMoMA systems with different biopolymers and highlight gelatin/oSMoMA bioinks as promising cytocompatible materials for stable 3D bioprinting applications in tissue engineering. Full article

Surgical intervention is a primary treatment for osteosarcoma, often resulting in a tumorous bone defect with an irregular shape. Postoperative management is essential to minimize tumor recurrence risks and promote bone regeneration. To address these issues, we developed a multifunctional injectable, rapidly photo-curable hydrogel composed of gelatin methacryloyl/carboxymethyl chitosan/hyaluronic acid (GelMA/CMCS/HA), modified with vanadium-doped mesoporous bioactive glass (VMBG). The exceptional injectability enables seamless adaptation to irregular bone defects, offering a significant advantage over preformed implants, while the rapid photocurability of the hydrogel ensures stable fixation within minutes, thereby reducing potential risks during surgery. Furthermore, this platform exhibits dual therapeutic efficacy, characterized by antitumor activity and osteogenic induction. In vitro assessments demonstrated that V(V)/V(IV) valence cycling-driven ROS generation mediated its potent antitumor efficacy. Additionally, concurrent enhancement of alkaline phosphatase activity and osteogenic marker expression validated its osteogenic potential. The CMCS incorporation promoted healing at the defect site, while the HA addition created binding sites for cell adhesion and growth, thereby improving scaffold bioactivity. Collectively, this study presents the development and validation of a multifunctional GelMA/CMCS/HA hydrogel, highlighting its dual capability for bone regeneration and tumor suppression within tumor-associated bone microenvironments. Full article

In this study, a hierarchical design strategy is introduced for tuning the release of rosmarinic acid (RA) from electrospun poly(L-lactide) (PLA) fibrous materials via surface engineering with chitosan/hyaluronic acid (Ch/HA) polyelectrolyte complexes (PECs). RA was selectively incorporated within the fiber bulk, the PEC coating, or both, enabling control over its spatial distribution. The PEC coating, formed by sequential dip coating, was shown to act as a diffusion-regulating layer with a dual role—either retarding RA release or promoting rapid initial release when functioning as a surface-associated reservoir. As a result, the release kinetics could be systematically tuned depending on the coating architecture and RA localization. Thorough characterization confirmed successful coating formation, enhanced surface hydrophilicity, and improved mechanical performance. All RA-loaded materials retained high antioxidant activity and exhibited pronounced antibacterial and antifungal effects against Staphylococcus aureus, Escherichia coli, and Candida albicans. This work introduces PEC-modified electrospun systems as a versatile platform for the rational design of multifunctional fibrous biomaterials with controlled release profiles, with potential applications in wound healing and drug delivery. Full article