Search Results (102)

Low-molecular-weight chitosan may exhibit improved dispersion and biological accessibility compared with high-molecular-weight chitosan, but direct comparisons in Asian seabass remain limited. This study evaluated dietary low-molecular-weight chitosan produced by combined gamma irradiation and hydrogen peroxide depolymerization. The untreated and degraded preparations had apparent GPC-derived molecular weights of approximately 85 and 10 kDa, respectively. Juvenile Asian seabass (Lates calcarifer) were fed a Control diet of 1.0% high-molecular-weight chitosan or low-molecular-weight chitosan at 0.25%, 0.5%, or 1.0% for four weeks. Growth, serum antioxidant and humoral immune parameters, tissue-specific gene expression, and resistance to Photobacterium damselae were evaluated. No treatment significantly affected growth or feed utilization. Both high- and low-molecular-weight chitosan reduced serum MDA relative to the Control, whereas selected antioxidant and immune responses differed among inclusion levels. The 0.5% low-molecular-weight treatment increased GSH and GPx activity, the 1.0% low-molecular-weight treatment produced the highest CAT activity, and the 0.25% low-molecular-weight treatment produced the highest total serum IgM. Low-molecular-weight chitosan generally produced broader tissue-specific transcriptional responses than 1.0% high-molecular-weight chitosan. Following bacterial challenge, all chitosan treatments improved survival relative to the Control, with the highest numerical RPS observed in the 0.5% low-molecular-weight group. These results indicate that molecular-weight reduction influenced the biological response to dietary chitosan. Among the tested levels, 0.5% produced the most consistent combined response, although the optimal level was endpoint-specific and requires longer-term validation. Full article

Backgorund/Objectives: Respiratory diseases represent a substantial global health burden and require effective localised pulmonary delivery strategies, particularly for poorly water-soluble therapeutic molecules. Nanoparticle-based drug delivery systems, especially those manufactured using microfluidics, have emerged as promising approaches to overcome pulmonary barriers, enhance local drug retention, and reduce systemic side effects. Among these nanocarriers, solid lipid nanoparticles (SLNs) and solid hybrid nanoparticles (SHNs) combine biocompatibility with controlled release and improved formulation stability. Methods: In this study, SLNs and lipid–chitosan SHNs were developed using microfluidic technology as candidate platforms for pulmonary drug delivery, with Cyclosporine A (CyA) used as a model hydrophobic cyclic peptide. Nanocarriers were produced using 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) and cholesterol as lipids, with low-molecular-weight chitosan incorporated to obtain hybrid systems. Physicochemical properties were evaluated using dynamic light scattering (DLS) and ζ potential measurements, while morphology and structural organisation were investigated using transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Results: The microfluidic approach enabled the production of nanoparticles with controlled sizes below 200 nm, narrow size distributions, and good reproducibility. In addition, the SHNs exhibited a positive surface charge, high encapsulation efficiency (~80%), and good colloidal and thermal stability. In vitro release studies showed an initial burst release followed by sustained CyA release, reaching approximately 94% cumulative release within 6 h. The Korsmeyer–Peppas model was used as the standard kinetic model. No blank nanoparticles were used as controls in the EE and release assay. Conclusions: Overall, these findings support further investigation of microfluidic-produced lipid and hybrid nanoparticles as candidate platforms for pulmonary drug delivery. Full article

It is known that the controlled release of anticancer drugs with low molecular weight from drug delivery systems (DDSs) based on polysaccharides such as chitosan (CS) still encounter certain difficulties because of the high hydrophilicity of the carrier. The release rate is very fast, with a burst release that is usually obvious. Therefore, finding novel systems to carry and release low molecular weight drugs such as 5-fluorouracil (5-FU) is still of interest. The impact of chitosan (CS) characteristics (deacetylation degree and molar mass), and concentration as well as of the strategy employed to fabricate porous nanocomposites CS–laponite (LAP), on the physicochemical properties of CS-LAP sponges was first investigated in the paper. Information about the incorporation of LAP within the CS-LAP nanocomposites was obtained by EDX and FTIR spectroscopy. The influence of the fabrication conditions on the physical cross-linking was evidenced first by the swelling of the composite sponges at equilibrium in distilled water, with lower values of the swelling ratio found for the composites prepared with one freeze-drying (1FD) step, than of those prepared with 2FD steps. The elastic modulus ranged between 6 and 21 kPa for CS-LAP composites prepared with 1FD, and between 2 and 10 kPa for the nanocomposites prepared with 2FD steps. The physicochemical properties of CS-LAP nanocomposite sponges were correlated with their behavior in the loading and in vitro release of 5-FU as a function of pH. It was found that the CS-LAP composites with the highest swelling ratio exhibited the fastest release of 5-FU in simulated gastric fluid (pH 2.0), with the cumulative release in the range of 85–100%, in about 60 min, at 37 °C. The CS-LAP composites with the lowest swelling ratio, displayed the slowest release rate of drug. The drug release from the double component composites was accompanied by the carrier dissolution/disintegration. To retard the release of 5-FU in the gastric environment, the drug was sealed in the porous CS-LAP nanocomposites by simple complexation of the free positive charges of CS with carboxymethylcellulose as polyanion. These systems kept their integrity at pH 2.0, pH 6.8 and phosphate buffer with pH 7.4, and released 5-FU in a controlled manner, making them suitable systems for delivery of 5-FU in both the stomach and small intestine. Full article

Hemodialysis (HD) remains the most widely adopted renal replacement therapy for patients with end-stage kidney disease; however, its delivery entails a substantial environmental burden due to high water and energy consumption and extensive reliance on single-use synthetic polymeric membranes. As the global prevalence of chronic kidney disease increases, the ecological footprint of dialysis systems has become a critical challenge for sustainable healthcare. Conventional HD membranes, based on petroleum-derived polymers, provide controlled permeability but are inherently non-renewable, non-biodegradable, and susceptible to fouling and bio-incompatibility, underscoring the need for alternative, more sustainable materials. Chitosan has emerged as a promising biopolymer owing to its biodegradability, intrinsic antimicrobial activity, chemical versatility, and favorable hemocompatibility. This review presents a comprehensive analysis of chitosan-based hybrid membranes for HD, with emphasis on sustainability-driven material innovation. The structural chemistry and functional properties of chitosan are discussed in relation to molecular weight, degree of deacetylation, and supramolecular organization, followed by a comparative assessment of chitosan derived from crustacean, insect, fungal, and cephalopod sources. Attention is given to fungal chitosan as a naturally deacetylated, high-purity, and reproducible biomaterial aligned with circular bioeconomy principles. Eco-innovative extraction and purification strategies, including enzymatic and low-energy processes, are critically examined alongside membrane fabrication approaches such as polymer blending, electrospinning of hollow fibers, and functionalization strategies aimed at improving hemocompatibility, antimicrobial performance, and fouling resistance. Key challenges related to membrane reuse, scale-up, regulatory compliance, and clinical translation are also addressed. Overall, this review highlights fungal-derived chitosan as a sustainable platform for next-generation HD membranes. Full article

This study evaluated the potential of synergistically degraded low-molecular-weight chitosan (LMW-CS) as a functional feed additive to promote growth, antioxidant capacity, innate immunity, and disease resistance in Pacific white shrimp (Litopenaeus vannamei). High-molecular-weight chitosan (HMW-CS, approximately 85 kDa) was degraded using γ-irradiation in combination with H₂O₂ to produce LMW-CS with improved functional properties. Shrimp were fed five experimental diets for 4 weeks: a control diet, HMW-CS0.4 (0.4% w/w), LMW-CS0.1 (0.1% w/w), LMW-CS0.2 (0.2% w/w), and LMW-CS0.4 (0.4% w/w). Growth performance, oxidative stress markers, antioxidant enzyme activities, lysozyme activity, immune-related gene expression, bacterial load, and survival after Vibrio parahaemolyticus challenge were evaluated. The results indicate that dietary LMW-CS supplementation improved growth performance and feed utilization, with LMW-CS0.2 showing significantly higher final weight, total weight gain, and average daily gain than the control group (p < 0.05). Antioxidant assays showed that LMW-CS reduced malondialdehyde levels and increased reduced glutathione, nitric oxide, glutathione reductase, catalase, superoxide dismutase, glutathione peroxidase, and glutathione-S-transferase activities in both plasma and hepatopancreas (p < 0.05). Lysozyme activity was significantly enhanced, particularly in the LMW-CS0.4 and HMW-CS0.4 groups (p < 0.05). Gene expression analysis revealed upregulation of genes associated with growth regulation, antimicrobial defense, pathogen recognition, and prophenoloxidase activation, including igf2, cstn, lgbp, lyz, and propo2. Gut microbiota profiling showed that chitosan supplementation altered bacterial community composition, reduced the relative abundance of some Vibrio-associated taxa, and descriptively lowered predicted pathogenic and stress-tolerant bacterial phenotypes. Following the Vibrio parahaemolyticus challenge, shrimp fed LMW-CS0.4 showed the lowest bacterial load and highest survival rate, indicating improved disease resistance (p < 0.05). Overall, synergistically degraded LMW-CS enhanced growth, redox balance, innate immune competence, gut microbial structure, and resistance to V. parahaemolyticus, supporting its potential as an antibiotic-free functional feed additive for sustainable shrimp aquaculture. Full article

Fenugreek seed oil contains bioactive constituents of interest for functional-food applications, but its susceptibility to environmental degradation may limit processing and storage. This study developed an alginate–chitosan encapsulation system and examined how chitosan molecular weight affected the physicochemical properties and in vitro bioactivity of the resulting formulations. Fenugreek seed oil was obtained by mechanical pressing and Soxhlet extraction, yielding 2.81% and 5.50% (v/w), respectively. The oil was incorporated into calcium-alginate beads (T₁), which were left uncoated or coated with high-molecular-weight chitosan (HMC; T₂) or low-molecular-weight chitosan (LMC; T₃). The formulations were characterized by color measurement, microscopy, scanning electron microscopy, Fourier-transform infrared spectroscopy, thermogravimetric analysis, and particle-size analysis of oil droplets released from the polymer matrix. Free and encapsulated oil samples were also exposed to UV-C irradiation and evaluated using antioxidant assays, an albumin-denaturation inhibition assay, and an α-amylase inhibition assay. Dry-product recovery ranged from 76.72% for T₂ to 94.79% for T₁, with T₃ showing a higher recovery than T₂. SEM showed that T₂ had the smoothest and most uniform dried morphology. FTIR spectra were consistent with interactions between alginate and chitosan while retaining characteristic bands associated with the oil. The chitosan-coated formulations also showed altered thermal-degradation profiles compared with alginate alone. After irradiation, T₃-UV showed DPPH radical-scavenging activity of 63.03% and albumin-denaturation inhibition of 94.95%, whereas T₂-UV showed the highest α-amylase inhibition. These findings indicate that chitosan molecular weight influences formulation recovery, morphology, thermal behavior, and measured in vitro activity. Further work using matched non-irradiated controls, standardized oil-equivalent concentrations, release testing, and gastrointestinal models is required before functional-food delivery claims can be established. Full article

This study evaluated the effect of chitosan with a high degree of deacetylation (75–85%) and three different molecular weights—low (50–190 kDa), medium (190–310 kDa), and high (310–375 kDa)—on the coating of vesicular systems. Chitosan solutions were characterized in acidulated aqueous medium by determining changes in pH, electrical conductivity, zeta potential, surface tension, viscosity, transmittance, particle size, and polydispersity index (PDI) with respect to polymer concentration. Subsequently, nanoliposomes were developed using an ethanol injection method assisted by ultra-high-pressure homogenization (UHPH) prior to coating. The characterization of the vesicular systems involved particle size analysis, polydispersity index (PDI), and zeta potential, which were evaluated at zero time and at the fourth week prior to storage at 4 °C and 40 °C. The physicochemical characterization of chitosan solutions displayed an inflection point at 1 × 10⁻³ M, which was taken as the coating concentration. In general, non-coated liposomes ranged between 150 and 200 nm, with low polydispersity (<0.3) and negative zeta potentials around ~−43 mV. Chitosan coating significantly increased particle size and PDI, while decreasing zeta potential values, but within the same negative value range, suggesting a slight interfacial coating effect. Finally, the systems subjected to UHPH and coated with high- and medium-molecular-weight chitosan showed interesting stabilization against storage conditions in the thermal stress tests. Full article

Background: Acute Lung Injury/Acute Respiratory Distress Syndrome (ALI/ARDS) is a fatal inflammatory disorder driven by M1 macrophages and the associated inflammatory cascade. Targeted drug delivery to these cells is a promising therapeutic strategy. Methods: L-arginine was conjugated to chitosan of different molecular weights. The resulting curcumin nanocrystals (Arg-CS-Cur) were characterized for conjugation efficiency, zeta potential, stability, and drug release profile. Cellular uptake mechanisms and mitochondrial targeting were investigated in lipopolysaccharide (LPS)-induced M1 macrophages using specific endocytic inhibitors and confocal microscopy. Results: Low-molecular-weight chitosan (MW 50 kDa) showed the highest L-Arg conjugation efficiency (22.31%). The optimized Arg-CS-Cur nanocrystals exhibited high zeta potential (±47.5 mV), excellent stability, and a superior drug release. They were internalized by M1 macrophages more efficiently than unmodified CS-Cur or free curcumin (p < 0.05). Uptake occurred via clathrin-mediated endocytosis (p < 0.001) and was mediated by CAT-2, which was highly expressed in M1 macrophages (p < 0.001). Arg-CS-Cur specifically targeted the mitochondria, reducing ROS and NLRP3 expression, thus inhibiting the NLRP3 inflammasome pathway (p < 0.001). Conclusions: This L-arginine-modified chitosan-based nanodelivery system synergistically exploits CAT-2 and clathrin pathways to deliver curcumin to M1 macrophage mitochondria, inhibiting the NLRP3 inflammasome. This dual-targeted strategy offers a promising approach for treating ALI/ARDS. Full article

The development of sustainable plant protection strategies requires stable and environmentally compatible delivery systems for beneficial microorganisms. In this study, Bacillus subtilis was encapsulated within chitosan-based cast films to evaluate bacterial viability, sustained biological activity, and antifungal efficacy. Films prepared from chitooligosaccharide (COS) and chitosans of low, medium, and high molecular weight (CS-LMW, CS-MMW, CS-HMW) were characterized in terms of morphology, mechanical performance, and pH-dependent swelling behavior. The viscosity of the chitosan solutions increased markedly with molecular weight from 73 cP (COS) to 614 cP (CS-HMW), while film thickness ranged from 34 ± 1.5 to 57 ± 2.3 µm. Mechanical performance improved significantly with increasing molecular weight, with maximum tensile stress exceeding 200 MPa for CS-HMW films, while swelling studies confirmed pronounced pH-dependent behavior consistent with the polyelectrolyte nature of chitosan. Encapsulation effectively preserved bacterial viability and metabolic activity over time. The intrinsic antifungal activity of chitosan synergized with the biocontrol activity of B. subtilis against Fusarium avenaceum and Alternaria solani. The highest antifungal performance was observed for CS-HMW films, which produced inhibition zones up to 84.6 ± 5.0 mm against A. solani. These findings demonstrate that chitosan-based cast films serve as effective carriers for beneficial microorganisms, providing environmental protection and regulated biological activity. The combination of a bioactive polymer matrix with a potent biocontrol agent represents a promising eco-friendly approach to sustainable plant protection. Full article

The enzymatic production of low-molecular-weight chitosan and chitooligosaccharides (COS), with broad application potential in agriculture, food, medicine, and cosmetics, has emerged as an attractive alternative to chemical chitosan depolymerization owing to its substrate specificity and environmentally benign catalytic action. However, the functional properties of available chitosanases need to be enhanced to meet the demands of industrial COS manufacturing under high temperature and substrate concentrations. In this work, we performed directed evolution on a recombinant Bacillus subtilis chitosanase to increase chitosan hydrolysis performance and thermal resistance. Three rounds of directed evolution screening (~9000 clones) yielded variants MT1, MT2, and MT3 with higher specific activity, achieved through Vmax improvement and increased T_1/2 at 60 °C. HPLC, DLS, and MALDI-TOF results indicate differences in the hydrolysis kinetics and size distribution of COS products over reaction time, suggesting a narrower distribution and a lower average molecular weight. Molecular dynamics simulations and docking studies revealed potential modulation of chitosanase activity via changes in the opening and closing dynamics of the active-site cleft. These results suggest that future efforts targeting the cleft interface could significantly advance both the catalytic performance and the mechanistic understanding of GH46 family chitosanases. Full article

Background: Human Immunodeficiency Virus type 1 (HIV-1) remains a major global health challenge. Despite advances in antiretroviral therapy, new prevention strategies are needed, particularly topical microbicides capable of blocking the earliest steps of viral entry. HIV-1 attachment relies on interactions with heparan sulfate proteoglycans on host cell surfaces; therefore, sulfated heparan-mimetic polymers have been explored as antiviral agents. In this context, sulfated chitosan microparticles are designed to mimic natural glycosaminoglycan receptors, acting as biomimetic decoys that prevent viral attachment and entry. Methods: Low-molecular-weight sulfated chitosan (LMW Chi-S) microparticles were synthesized and characterized (SEM, EDS, DLS, FTIR) following US Patent No. 11,246,839 B2. Their antiviral activity was evaluated by incubating the microparticles with high-viral-load HIV-1-positive plasma (~3.5 × 10⁶ copies/mL) to enable viral binding and removal by pull-down. The performance of the synthesized Chi-S microparticles was compared with established heparinoid controls, including soluble heparin and heparin microparticles. Results: Chi-S microparticles exhibited stronger virus-binding and neutralizing capacity than all heparinoid comparators, achieving up to 70% reduction in viral load relative to untreated HIV-1 plasma. In comparison, soluble heparin and heparin microparticles reduced viral load by approximately 53% and 60%, respectively. Subsequent evaluation across multiple tested concentrations confirmed a consistent antiviral effect, indicating that the synthesized Chi-S microparticles maintain robust virus–particle interactions throughout the concentration range examined. Conclusions: These findings demonstrate that LMW Chi-S microparticles possess potent antiviral properties and outperform classical heparinoid materials, supporting their potential application as topical microbicides targeting early HIV-1 entry mechanisms. Full article

The valorization of shrimp shell waste is crucial for promoting sustainability and a circular economy. This study aimed to extract chitin from the exoskeletal residues of deep-water rose shrimp (Parapenaeus longirostris) sourced from the Marmara Sea and synthesize low-molecular-weight chitosan (LMWC) via conventional, microwave-, and autoclave-assisted deacetylation pathways. The shell biomass was subjected to sequential demineralization (1 M HCl) and deproteinization (1 M NaOH), yielding 14.42% chitin. The extracted chitin was then converted to LMWC using the three methods, and the products were characterized using FT-IR spectroscopy, titration, viscometry, SEM, and TGA. The results demonstrated that the autoclave-assisted method achieved the highest degree of deacetylation (DD) at 95%, significantly outperforming the conventional method (81%) and the microwave-assisted method (67%). The autoclave-synthesized chitosan also exhibited the lowest viscosity (33 cP), confirming its low molecular weight. Morphological analysis showed that chitin exhibited a well-defined fibrous structure. After deacetylation, this structure transformed into a rough and porous surface morphology. Thermal analysis further demonstrated that the laboratory-synthesized chitosan exhibited higher thermal stability than the commercial chitosan sample. In conclusion, the autoclave-assisted method proved to be highly efficient for producing low-molecular-weight chitosan with a high degree of deacetylation. However, the conventional method remains the most practical option for scalable industrial production due to its simplicity and well-established infrastructure. Moreover, the laboratory-synthesized chitosan exhibited higher thermal stability, increased porosity, and a higher degree of deacetylation compared to commercially available chitosan, which may offer functional advantages in applications requiring enhanced reactivity, solubility, or thermal resistance. Overall, the findings provide valuable insights into selecting appropriate deacetylation strategies for producing low-molecular-weight chitosan with tailored properties, thereby bridging the gap between laboratory-scale synthesis and potential industrial applications. Full article

High-performance spun bionanocomposite fibers, composed of high-molecular-weight chitosan (HMW), low-molecular-weight chitosan “oligomers” (LMW), and cellulose nanofibers (CNFs), were successfully fabricated via gel spinning of viscous aqueous chitosan (CHI) based formulations into a NaOH coagulation bath. The X-ray diffraction (XRD) analysis revealed that the incorporation of cellulose nanofibers contributed to enhance crystallinity of chitosan in spun fibers. The spinning process, which comprised sequential acidic solubilization, basic neutralization, stretching, and drying steps, produced chitosan/CNF composite fibers with high crystallinity, further enhanced by the incorporation of low molecular weight chitosan. The cellulose nanofibers seem to promote CHI crystallization, by acting as nucleation sites for the nucleation and growth of chitosan crystals, with those latter of LMW further enhancing crystallization and orientation due to higher mobility of shorter polymer chains. Two-dimensional XRD patterns demonstrated the preferential alignment of both CNFs and chitosan crystals along the fiber axis. Increasing the proportion of short-chain chitosan led to a reduction of the viscosity of collodion, facilitating the spinning of solutions with higher polymer concentrations. The X-ray diffraction (XRD) analysis revealed that the addition of low-molecular-weight chitosan (LMW), with an intermediate molecular weight Mw of ~4.4 × 10⁴ g/mol, produced the most significant improvements in the crystallinity index (CrI) and orientation. This structural enhancement corresponded to superior mechanical properties like Young’s modulus, yield stress σ_y, and stress-at-break σ_b of the processed composite fibers. By incorporating that intermediate molecular weight chitosan, a Young’s modulus as high as 20 GPa was achieved for the spun composite fibers, which was twice higher than the modulus of around 10 GPa obtained by adding the lowest molecular weight chitosan of Mw ~ 2.9 × 10⁴ g/mol in the composite, and largely above the modulus of around 5 GPa obtained for fiber just spun with chitosan without incorporation of cellulose nanofibers. Full article

Chitin deacetylases (CDAs), which catalyze the deacetylation of chitin to produce chitosan, have garnered significant interest due to their environmental compatibility and ability to control product quality. However, the low conversion efficiency resulting from chitin’s high molecular weight and crystallinity, as well as structural limitations of CDAs, has impeded their industrial application. In this study, we present the integrated approach combining bioinformatics and computational tools (adaptive Poisson–Boltzmann solver, Fpocket, and ProteinPlus) to systematically analyze sequence features and variations in active pocket properties among CDAs from diverse origins. Experimental evaluation of the deacetylation activity of AnCDA, AsCDA, BaCDA, and ScCDA, each with distinct pocket characteristics, on chitin substrates with varying molecular parameters revealed that CDAs with high hydrophobicity scores and low surface-to-volume ratios exhibited superior efficiency in converting high-molecular-weight chitin. These findings guide the rational selection and engineering of CDAs for industrial biocatalysis. Full article

The use of advanced wound dressings can significantly support the skin healing process by maintaining optimal conditions for tissue regeneration. In this study, foam-like dressings composed of agarose and chitosan, enriched with vitamin C, were developed using a simple and cost-effective freeze-drying method. Three types of chitosan with varying molecular weights (low, medium, high) were used to investigate their impact on the biological, physicochemical, and mechanical properties of the resulting foams. All fabricated biomaterials were biocompatible, non-toxic, and did not promote cell adhesion to their surfaces. The foams exhibited highly porous, hydrophilic microstructures with excellent fluid absorption capacity (~20 mL/g) and sustained vitamin C release over the first 24 h. Chitosan molecular weight had no significant effect on biological properties, but influenced samples’ wettability and mechanical parameters. The hydrophilic character of samples was observed in all tested biomaterials, with the strongest enhancement of hydrophilicity noted for the low molecular weight variant. The highest tensile strength was observed in samples prepared with medium molecular weight chitosan. The results indicate that among the analyzed variants, agarose-chitosan foam biomaterials containing medium molecular weight chitosan exhibited the most favorable properties, making them the most promising candidates for the treatment of wounds with excessive exudate. Full article