Search Results (1,397)

Background/Objective: Staphylococcus aureus (S. aureus) is a clinically significant pathogenic bacterium. Daptomycin (DAP) is a cyclic lipopeptide antibiotic used to treat infections caused by multidrug-resistant Gram-positive bacteria, including S. aureus. However, DAP currently faces clinical limitations due to its short half-life, toxic side effects, and increasingly severe drug resistance issues. This study aimed to develop a biomimetic nano-drug delivery system to enhance targeting ability, prolong blood circulation, and mitigate resistance of DAP. Methods: DAP-loaded chitosan nanocomposite particles (DAP-CS) were prepared by electrostatic self-assembly. Macrophage membrane vesicles (MM) were prepared by fusion of M1-type macrophage membranes with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC). A biomimetic nano-drug delivery system (DAP-CS@MM) was constructed by the coextrusion process of DAP-CS and MM. Key physicochemical parameters, including particle diameter, zeta potential, encapsulation efficiency, and membrane protein retention, were systematically characterized. In vitro immune escape studies and in vivo zebrafish infection models were employed to assess the ability of immune escape and antibacterial performance, respectively. Results: The particle size of DAP-CS@MM was 110.9 ± 13.72 nm, with zeta potential +11.90 ± 1.90 mV, and encapsulation efficiency 70.43 ± 1.29%. DAP-CS@MM retained macrophage membrane proteins, including functional TLR2 receptors. In vitro immune escape assays, DAP-CS@MM demonstrated significantly enhanced immune escape compared with DAP-CS (p < 0.05). In the zebrafish infection model, DAP-CS@MM showed superior antibacterial efficacy over both DAP and DAP-CS (p < 0.05). Conclusions: The DAP-CS@MM biomimetic nano-drug delivery system exhibits excellent immune evasion and antibacterial performance, offering a novel strategy to overcome the clinical limitations of DAP. Full article

Introduction. Larvae of the insect Hermetia illucens can represent an alternative source for low-molecular-weight chitosan (CS) production compared with CS from crustaceans (CS_crustac), making it appealing in terms of pharmaceutical applications. Hence, the performances of CS_larvae and CS_crustac were compared herein by investigating the in vitro features of nanoparticles (NPs) made from each polysaccharide and administered with the antioxidant quercetin (QUE). Methods. X-ray diffraction and FT-IR spectroscopy enabled the identification of each type of CS. Following the ionic gelation technique and using sulfobutylether-β-cyclodextrin as a cross-linking agent, NPs were easily obtained. Results. Physicochemical data, release studies in PBS, and the evaluation of antioxidant effects via the 1,1-diphenyl-2-picrylhydrazyl (DPPH) test were studied for both CS_larvae and CS_crustac. QUE-loaded NP sizes ranged from 180 to 547 nm, and zeta potential values were between +7.5 and +39.3 mV. In vitro QUE release in PBS was faster from QUE-CS_larvae NPs than from CS_crustac, and high antioxidant activity—according to the DPPH test—was observed for all tested NP formulations. Discussion. The agar diffusion assay, referring to Escherichia coli and Micrococcus flavus, as well as the microdilution assay, showed the best performance as antimicrobial formulations in the case of QUE-CS_larvae NPs. QUE-CS_larvae NPs can represent a promising vehicle for QUE, releasing it in a sustained manner, and, relevantly, the synergism noticed between QUE and CS_larvae resulted in a final antimicrobial product. Conclusions. New perspectives for low-molecular-weight CS are disclosed by adopting renewable sources from insects instead of the commercial CS_crustac. Full article

The search for sustainable, economically viable, and effective plant protection strategies against pathogenic bacteria, fungi, and viruses is a major challenge in modern agricultural practices. Chitosan (CS) is an abundant cationic natural biopolymer known for its biocompatibility, low toxicity, and antimicrobial properties. Its potential use in agriculture for pathogen control is a promising alternative to traditional chemical fertilisers and pesticides, which raise concerns regarding public health, environmental protection, and pesticide resistance. This study focused on the preparation of chitosan nanoparticles (CS-NPs) through cross-linking with organic molecules, such as tannic acid (TA). Various formulations were explored for the development of stable nanoscale particles having encapsulation capabilities towards low compounds of varying polarity and with potential agricultural applications relevant to plant health and growth. The solution properties of the NPs were assessed using dynamic and electrophoretic light scattering (DLS and ELS); their morphology was observed through atomic force microscopy (AFM), while analytical ultracentrifugation (AUC) measurements provided insights into their molar mass. Their properties proved to be primarily influenced by the concentration of CS, which significantly affected its intrinsic conformation. Additional structural insights were obtained via infrared and UV–Vis spectroscopic measurements, while detailed fluorescence analysis with the use of three different probes, as model cargo molecules, provided information regarding the hydrophobic and hydrophilic microdomains within the particles. Full article

The demand for anion exchange membranes (AEMs) is growing due to their applications in water electrolysis, CO₂ reduction conversion and fuel cells, as well as water treatment, driven by the increasing energy demand and the need for a sustainable future. However, current AEMs still face challenges, such as insufficient permeability and stability in strongly acidic or alkaline media, which limit their durability and the sustainability of membrane fabrication. In this study, polyvinyl alcohol (PVA) and chitosan (CS) biopolymers are selected for membrane preparation. Zinc oxide (ZnO) and porous organic polymer (POP) nanoparticles are also introduced within the PVA-CS polymer blends to make mixed-matrix membranes (MMMs) with increased OH⁻ transport sites. The membranes are characterized based on typical properties for AEM applications, such as thickness, water uptake, KOH uptake, Cl⁻ and OH⁻ permeability and ion exchange capacity (IEC). The OH⁻ transport of the PVA-CS blend is increased by at least 94.2% compared with commercial membranes. The incorporation of non-porous ZnO and porous POP nanoparticles into the polymer blend does not compromise the OH⁻ transport properties. On the contrary, ZnO nanoparticles enhance the membrane’s water retention capacity, provide basic surface sites that facilitate hydroxide ion conduction and reinforce the mechanical and thermal stability. In parallel, POPs introduce a highly porous architecture that increases the internal surface area and promotes the formation of continuous hydrated pathways, essential to efficient OH⁻ mobility. Furthermore, the presence of POPs also contributes to reinforcing the mechanical integrity of the membrane. Thus, PVA-CS bio-based membranes are a promising alternative to conventional ion exchange membranes for various applications. Full article

Chronic infected wounds remain a major medical challenge, particularly in the context of increasing antibiotic resistance. The objective of this study was to develop and evaluate chitosan-based (CS) sponges enhanced with graphene oxide (GO) as potential antimicrobial wound dressings. The composite sponges were fabricated using microcrystalline CS (MKCh) and 5% (w/w) GO, followed by freeze-drying and γ-sterilization (25 kGy). Physico-mechanical characterization showed that GO incorporation did not significantly alter tensile strength, while absorption and sorption capacities were improved, especially after sterilization. Structural and spectroscopic analyses confirmed increased porosity and molecular interaction between CS and GO. Cytocompatibility was verified in vitro using L-929 fibroblasts, with no cytotoxic effects observed in indirect contact. Antimicrobial activity tests demonstrated that GO-modified dressings exhibited enhanced activity against E. coli and S. aureus, though results were strain-dependent and not uniformly superior to CS alone. Notably, antifungal efficacy against C. albicans was reduced with GO addition. Overall, the developed GO-enriched CS sponges present favorable biocompatibility, mechanical resilience, and selective antimicrobial activity, supporting their potential application in chronic wound management. Further optimization of GO concentration and formulation is warranted to maximize antimicrobial efficacy across a broader spectrum of pathogens. Full article

Background/Objectives: One current cancer treatment is immunotherapy, in which tumor antigens (such as MAGE) or adjuvants (such as CpGs) can be used to induce the destruction of tumor cells by the immune system; however, the therapeutic response is generally weak. Therefore, it is necessary to develop a strategy that increases the immune response induced by tumor antigens and CpGs. We propose the coupling of tumor antigens and adjuvants to chitosan (Cs) microparticles to improve the immune response against cancer, as these microparticles can activate the innate immune response when recognized by macrophages and dendritic cells (DCs). Methods: Cs microparticles coupled with CpGs and tumor antigens were constructed with the emulsification method; then, their morphology, in vitro biological effect on DCs, and therapeutic effect in a murine melanoma model were analyzed. Results: The Cs microparticles showed a rounded morphology and a size of approximately 5 μ; in addition, they were not cytotoxic in in vitro assays and induced the production of IFNα. Finally, in the murine model of melanoma, treatment with Cs microparticles coupled to MAGE or CpGs reduced the tumor growth rate and increased both survival and the presence of cell death areas in the tumor parenchyma in contrast to the control group. Conclusions: The results suggest that treatment with Cs microparticles coupled to tumor antigen and/or CpGs can be considered a promising strategy in the field of immunotherapy based on the use of biomaterials. Full article

This study addresses the challenge of chitosan (CS) being difficult to dissolve in water due to its highly ordered crystalline structure. Chitosan is modified with chloroacetic acid to reduce its crystallinity and enhance its water solubility. Through single-factor experiments, the optimal conditions for preparing carboxymethyl chitosan film (CMCS) were determined: under conditions of 50 °C, a cellulose substrate (CS) concentration of 18.75 g/L, a NaOH concentration of 112.5 g/L, and a chloroacetic acid concentration of 18.75 g/L, the reaction proceeded for 5 h. Under these conditions, the resulting carboxymethyl chitosan film exhibited the best flocculation effect, forming chitosan films in water that had flocculation activity toward mung bean starch protein wastewater. The successful introduction of carboxyl groups at the N and O positions of the chitosan molecular chain, which reduced the crystallinity of chitosan and enhanced its water solubility, was confirmed through analysis using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The prepared carboxymethyl chitosan film (CMCS) was applied in the flocculation recovery of protein. Through single-factor and response surface experiments, the optimal process conditions for flocculating and recovering protein with CMCS were determined: a CMCS dosage of 1.1 g/L, a reaction time of 39.6 min, a reaction temperature of 42.7 °C, and a pH of 5.2. Under these conditions, the protein recovery rate reached 56.97%. The composition and amino acid profile of the flocculated product were analyzed, revealing that the mung bean protein flocculated product contained 62.33% crude protein. The total essential amino acids (EAAs) accounted for 52.91%, non-essential amino acids (NEAAs) for 47.09%, hydrophobic amino acids for 39.56%, and hydrophilic amino acids for 12.67%. The ratio of aromatic to branched-chain amino acids was 0.31, and the ratio of basic to acidic amino acids was 1.68. These findings indicate that the recovered product has high surface activity and good protein stability, foaming ability, and emulsifying properties. Full article

Introduction: Functional endoscopic sinus surgery is commonly performed to treat paranasal sinus diseases, often necessitating nasal packing to control bleeding and aid healing. However, current materials can cause discomfort or lack adequate antibacterial properties. This study aimed to develop a biodegradable, biocompatible nasal packing material by combining polyvinyl alcohol (PVA) and carbon dots (CDs), and to evaluate its antibacterial activity and tissue compatibility. Materials and Methods: Electrospun nanofiber membranes were fabricated using PVA and biomass-derived CDs. Antibacterial efficacy of nasal packing variants (PVA, PVA-chitosan [CS], PVA-CS-CDs-1 mL, and PVA-CS-CDs-2 mL) was assessed using the Kirby–Bauer disk diffusion method against Escherichia coli, Salmonella spp., and Staphylococcus aureus. The in vivo biocompatibility was evaluated via histological analysis following implantation into the nasal cavity of mice. Results: All materials demonstrated antibacterial activity, with PVA-CS-CDs-2 mL showing the largest inhibition zones. Histological examination revealed minimal epithelial damage and no inflammation, with PVA-CS-CDs-2 mL yielding the most favorable tissue response. Conclusion: The PVA-CS-CDs composite demonstrates potential as a biocompatible, antibacterial nasal packing material. Further studies are warranted to validate its long-term clinical utility. Full article

Background: Chitosan (CS) crosslinked with genipin (GNP) provides a mild, non-toxic route to generate nanogels (NGs) with enhanced integrity and colloidal stability. Objectives: To develop and characterise CS-GNP NG as a novel platform for targeted cellular delivery, optimising design through physicochemical characterisation and biocompatibility evaluation. Methods: NGs were synthesised under optimised conditions by adjusting the pH of the CS solution, followed by high-intensity ultrasound (HIUS) to achieve disaggregation. Physicochemical characterisation was carried out using UV-Vis spectroscopy, FTIR, dynamic light scattering (DLS), and scanning electron microscopy (SEM). Rheological studies and SAXS analysis assessed structural properties. Biocompatibility was evaluated via MTT assay, and internalisation was monitored by fluorescence microscopy on mammalian cell lines. Results: NG formation was highly pH-dependent, with optimal configuration at pH 4.5, yielding stable, uniformly sized particles (~200 nm, ζ-potential +29 mV). Kinetic modelling showed a sigmoidal formation pattern, suggesting nucleation, growth, and stabilisation. FTIR confirmed covalent bonding between CS and GNP via primary amide bonds and Schiff bases. Rheology indicated pseudoplastic behaviour, and SAXS revealed a compact network formation. Biocompatibility assays confirmed non-cytotoxicity below 100 µg/mL and efficient cellular uptake. Conclusions: This study presents a rapid, reproducible protocol for generating colloidally stable, biocompatible NGs suitable for drug delivery. Full article

This work aims to study the catalytic properties of Fe, Cr, and Cu catalysts deposited on chitosan–silica (SBA-15) composites in liquid phase oxidation of cyclohexane (CH) with H₂O₂ and photocatalytic hydrogen evolution reaction. The catalysts were obtained by consecutive adsorption of chitosan (CS) and metal ions (Fe³⁺, Cr³⁺, Cu²⁺) on SBA-15 at ambient conditions. Characterization of the catalysts by XRD, IR spectroscopy, XPS, TEM, SEM, etc., showed the CS and metal ion adsorption on the solid support. Modification with CS provided better immobilization of the metal ions on SBA-15. The synthesized catalysts demonstrated different performance in liquid phase oxidation of cyclohexane with H₂O₂ under mild conditions at 40 °C and atmospheric pressure. Cyclohexane conversion on Fe–CS/SBA-15 (18.5%) and Cr–CS/SBA-15 (21.6%) was higher than on Cu–CS/SBA-15 (9.3%). The influence of different conditions of the reaction such as time, temperature, catalyst dosage, substrate and oxidant ratio on cyclohexane conversion in the presence of the most efficient Cr–CS/SBA-15 catalyst was also studied. The optimal reaction conditions were found to be the following: duration of reaction—4 h, temperature of reaction—50 °C, m_cat—0.03 g, a substrate/H₂O₂ ratio of 1:3. In addition, Cr–CS/SBA-15 and Fe–CS/SBA-15 catalysts were studied in a photocatalytic H₂ evolution reaction. The Fe-containing catalyst demonstrated superior efficiency in photocatalytic H₂ evolution. The total volume of hydrogen produced within 3 h was 103 mL/g. Thus, this study demonstrates that chitosan possesses promising potential in the design of the supported catalysts for cyclohexane oxidation and photocatalytic hydrogen evolution reactions. Full article

Despite its broad application due to its affordability, biodegradability, and natural antimicrobial and antioxidant activities, chitosan (CS) still exhibits limitations in mechanical strength and barrier effectiveness. Owing to its unique chemical characteristics, itaconic acid (IT) presents potential as a compatibilizing agent in polymeric blend formulations. Biodegradable polymers composed of chitosan (CS), itaconic acid (IT), and starch (S) were synthesized using two polymerization methods. The first method involved grafting IT onto CS at varying ratios of IT (4%, 6%, and 8% wt.), using 1% v/v acetic acid/water as the solvent and potassium persulfate as the initiator. In the second approach, starch (S) was blended with the copolymer P(CS-g-IT) at concentrations of 1%, 3%, and 5%, utilizing water as the solvent and glacial acetic acid as a catalyst. The resulting biodegradable films underwent characterization through FTIR, TGA, SEM, and mechanical property analysis. To further explore the effects of combining IT, starch, and carbon black, the blends, referred to as P[(CS-g-IT)-b-S], were also loaded with carbon black. This allowed for the evaluation of the materials’ physicomechanical properties, such as viscosity, tensile strength, elongation, and contact angle. The findings demonstrated that the presence of IT, starch, and carbon black collectively improved the films’ mechanical performance, physical traits, and biodegradability. Among the samples, the blended copolymer with 1% starch exhibited the highest mechanical properties, followed by the grafted copolymer with 8% IT and the blended copolymer mixed with carbon black at 7%. In contrast, the blended copolymer with 5% starch showed the highest hydrophilicity and the shortest degradation time compared to the grafted copolymer with 8% IT and the blended copolymer mixed with 7% carbon black. Full article

Ferulic acid (FA) exhibits beneficial properties in ulcerative colitis (UC) pathogenesis, while sensitivity to the environment and enzymes limits its use in UC therapy. Therefore, this study aims to develop a colon-targeted nanocomplex delivery system using FA and investigate its protective effects and underlying regulatory mechanisms in UC mice. A novel Zein/FA–pectin (PEC)/chitosan (CS) nanocomplex was successfully fabricated in this study. Through systematic adjustment of the PEC/CS-to-Zein/FA ratio, optimal encapsulation efficiency (60.1%) and loading capacity (26.2%) were achieved. The characterized data indicated that hydrogen bonds, electrostatic interactions, and hydrophobic forces were the main driving forces maintaining the formation of the nanocomplexes, accompanied by alterations in the secondary structure of Zein. The Zein/FA–PEC/CS nanocomplexes demonstrated excellent thermal/storage particle size stability and exhibited both protective and sustained-release effects of FA during simulated gastrointestinal digestion. Furthermore, the results demonstrated that the nanocomplexes potentially alleviate UC by regulating inflammatory cytokines, oxidative stress, and gut microbiota. Compared to unencapsulated FA, the nanocomplexes have a better effect on alleviating UC symptoms. In summary, Zein/FA–PEC/CS nanocomplexes have promising prospects in alleviating colitis in UC mice. Full article

The growing demand for sustainable materials has led to innovation in the development of natural compound-based solutions for industrial applications. This study introduces composite nanoparticles (NP-CsYBE) synthesized from chitosan (Cs) and saponin-rich yucca extract (YBE), highlighting their application in Pickering emulsions (PE). Characterization via DLS and AFM revealed NP-CsYBE as spherical particles with a hydrodynamic diameter of 230 nm and a ζ-potential of +36.9 mV, showing a non-aggregated morphology. Comparative analyses of emulsions formulated with Cs nanoparticles (Cs-NP) and YBE were conducted to assess the individual contributions of each component. Functional evaluations revealed that PE based on NP-CsYBE exhibited superior stability over time compared to those with Cs-NP or YBE alone. Additionally, the rheological properties of NP-CsYBE PE were influenced by pH: liquid-viscous behavior dominated at pH 4, while at pH 6.5, solid-elastic properties prevailed. Notably, increased temperature enhanced its mechanical properties. This innovative approach provides a framework for applying natural nanoparticles in PE formation, offering potential applications in the pharmaceutical, food, medical, and cosmetic industries, as well as biomaterials for protecting lipophilic substances. By leveraging natural resources, this work advances the understanding of natural nanoparticle-based systems and their role in developing sustainable and functional materials for industrial use. Full article

This study develops a novel dual-layer chitosan (CS)/pectin film incorporating grape skin anthocyanin extract (GSAE) and lignin to address critical limitations in cherry preservation. Unlike traditional methods that leave harmful residues, this bilayer design separately integrates functional components: GSAE for targeted antioxidant/antibacterial action and lignin for ultraviolet (UV) blocking. This targeted incorporation enables synergistic performance unattainable with single-layer or conventional approaches. The films, fabricated with lignin concentrations from 1% to 15% (w/v), demonstrated excellent mechanical integrity (assessed with structural characterization), optimized gas barrier performance, and effective UV attenuation (achieved via lignin incorporation). Antibacterial analyses confirmed substantial inhibition against Staphylococcus aureus and Escherichia coli. Crucially, cherry preservation tests showed that the 15% lignin film (PG/CL15%) reduced weight loss, preserved firmness, and extended shelf life by 8 days—a significant quantitative improvement over uncoated fruit. Structural characterization (TGA, FT-IR, and XRD) verified successful GSAE/lignin embedding via hydrogen bonding. Beyond cherries, this dual-layer, bio-based design offers a promising template for the active packaging of other perishable produce sensitive to oxidation, microbial spoilage, and UV degradation, which enhances its industrial relevance. Full article

Candida auris is an emerging multidrug-resistant fungal pathogen with a high affinity for skin colonization and significant potential for nosocomial transmission. This study aimed to develop and evaluate chitosan-based hydrogels loaded with nystatin and propolis as a topical antifungal strategy for skin decolonization of C. auris. The formulations were selected based on our previous results and optimized for cutaneous application. The internal structure of the hydrogels was investigated by polarized light microscopy, confirming the amorphous nature of propolis and the partial dispersion of nystatin. The antifungal activity was assessed against ten fluconazole-resistant C. auris strains. The CS-NYS-PRO1 formulation demonstrated the highest antifungal performance in the agar test, also reducing viable cell counts to undetectable levels within 6 h. Time–kill assays and SEM imaging confirmed the rapid fungicidal effect and revealed severe membrane disruption and cytoplasmic leakage. Molecular docking analyses indicated the strong binding of nystatin to both sterol 14α-demethylase (CYP51) and dihydrofolate reductase (DHFR) from C. auris, suggesting complementary membrane and intracellular mechanisms of action. These findings support the use of such hydrogels as a local, non-invasive, and biocompatible strategy for managing C. auris colonization, with promising implications for clinical use in infection control and the prevention of skin-mediated transmission in healthcare settings. Full article