Search Results (1,225)

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

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

Biodegradable films based on polysaccharides have attracted attention as sustainable alternatives for food preservation. In this study, films and films were developed using cassava starch, chitosan, and grape seed extract, either individually or in polymeric blends, and their physicochemical, mechanical, microstructural, and preservative properties were evaluated. The films were applied to peeled shrimp stored under refrigeration for six days. Microbiological analysis showed a reduction in aerobic mesophilic bacterial counts in coated samples, indicating improved preservation. Films containing cassava starch and chitosan provided greater pH stability during storage. Film characterization revealed that grape seed extract influenced thickness and solubility, particularly in chitosan-based formulations. Cassava starch films exhibited the best water vapor permeability, while blended systems demonstrated improved mechanical performance. The highest tensile strength was observed for the chitosan-based film with extract, whereas starch-containing blends showed balanced strength and flexibility. Scanning electron microscopy revealed more cohesive and continuous structures in polymer blends, while extract-only films presented internal voids, explaining their lower mechanical resistance. Thus, the synergistic combination of cassava starch and chitosan, modulated by grape seed extract, produced films with suitable barrier, mechanical, and structural properties. These biodegradable polymeric films show promising potential for extending the shelf life of refrigerated shrimp and for application in sustainable food packaging. Full article

The growing demand for sustainable packaging materials has accelerated interest in biomass-derived carbon fillers as functional reinforcements for biodegradable polymer composites. This review critically evaluates the use of carbon materials produced from agricultural residues, particularly palm kernel shell (PKS) and coconut shell (CS), in biopolymer composite coating films for food packaging applications. Recent thermochemical conversion routes, including carbonization, activation, and catalytic graphitization, are discussed in relation to their influence on filler morphology, porosity, surface chemistry, and graphitic ordering. Particular emphasis is placed on structure–property relationships in composite systems containing matrices such as polylactic acid (PLA), starch, chitosan, gelatin, and polyvinyl alcohol (PVA). Published studies indicate that properly dispersed carbon fillers can improve tensile strength, thermal stability, ultraviolet shielding, and oxygen/water vapor barrier performance through stress-transfer mechanisms and tortuous diffusion pathways. However, excessive filler loading or poor interfacial compatibility frequently causes agglomeration, brittleness, and loss of transparency. Surface modification strategies including oxidation, silanization, and surfactant-assisted dispersion, are therefore reviewed as key approaches to optimize composite performance. Finally, current limitations involving migration safety, process scalability, and the lack of standardized testing protocols are discussed. Overall, PKS- and CS-derived carbon fillers represent promising sustainable additives for next-generation biopolymer composite packaging systems. Full article

Chronic and infected wounds remain difficult to treat due to persistent microbial burden, biofilm formation, and dysregulated inflammation. As a multifunctional polyphenol, curcumin exhibits broad-spectrum antimicrobial, anti-inflammatory, and antioxidant activities. Nevertheless, the clinical application of curcumin is constrained by its limited solubility in water, inherent instability, and insufficient bioavailability. Chitosan, a cationic polysaccharide, provides complementary advantages including intrinsic antimicrobial activity, mucoadhesion, and the capacity to form versatile delivery platforms such as nanoparticles, hydrogels, and films. This review reframes chitosan–curcumin systems as dual-function bioactive platforms in which both the carrier and payload actively contribute to therapeutic outcomes. Mechanistically, chitosan disrupts microbial membranes, enhances bioadhesion, and supports tissue regeneration, while curcumin modulates intracellular targets including reactive oxygen species, quorum sensing, and inflammatory signaling pathways. Their integration enables multimodal antimicrobial activity, improved biofilm disruption, and coordinated regulation of the wound-healing cascade. This review critically examines the structure–function relationships governing release kinetics, stability, and cytocompatibility, with particular emphasis on chitosan molecular weight, degree of deacetylation, crosslinking strategies, and curcumin loading. Solubility-enhancement strategies for curcumin, including surfactants, nanoparticles, solid dispersions, and chemical derivatives, are evaluated in the context of antimicrobial efficacy and cytotoxicity. Finally, the review highlights translational challenges and future directions, such as antibiotic synergy, antifungal applications, formulation complexity, and the emerging role of artificial intelligence in predictive material design. Collectively, these insights establish design principles for next-generation multifunctional biomaterials that integrate antimicrobial activity with immune modulation and tissue repair. Full article

This study investigated the development, fabrication, and characterization of a novel biodegradable food packaging film based on chitosan (CH) and fucoidan (FU), incorporating blackcurrant-derived anthocyanins (BCAs). The system was designed to enable real-time monitoring of tuna (Thunnus spp.) freshness, while addressing environmental concerns through the replacement of synthetic materials with a bioactive, multifunctional alternative that provides both mechanical protection and dynamic spoilage indication. Films were prepared using a casting method with varying BCA concentrations (0.2%, 0.4%, and 0.6%) and systematically evaluated in terms of their structural, physicochemical, and biological properties. The results indicated that the CH/FU/BCA film containing 0.4% BCA exhibited optimal performance, characterized by enhanced tensile strength, reduced water solubility and moisture content, and improved thermal stability and barrier properties. The incorporation of BCA enabled distinct color changes in response to spoilage-related conditions, supporting its function as a pH-responsive indicator. In addition, the films demonstrated significant antimicrobial activity against Escherichia coli and Staphylococcus aureus, affirming their suitability as active packaging materials. Zeta potential analysis further indicated improved colloidal stability upon BCA incorporation. Overall, the synergistic interactions among CH, FU, and BCA resulted in a multifunctional film with combined protective and freshness-indicating capabilities. These findings highlight the potential of the developed biofilm for application in intelligent seafood packaging systems. Full article

In this work, we propose a bamboo-shaped Mach-Zehnder interferometer coated with chitosan for relative humidity (RH) and temperature measurement. The sensor is fabricated by fusing no-core fiber and multimode fiber segments through arc discharge, followed by tapering with a hydrogen–oxygen flame to form a unique bamboo-shaped configuration. To functionalize the structure for humidity sensing, chitosan is coated onto the fiber surface. The refractive index of chitosan varies with water molecule adsorption, which enhances the spectral response of the sensor to RH. Therefore, the sensitivity response is enhanced after the film coating is applied. Experimental results demonstrate that the proposed sensor achieves the maximum sensitivities to RH and temperature determined at −0.9261 nm/%RH and 0.0952 nm/°C, respectively. The sensor features a compact structure, high sensitivity and the ability to achieve dual-parameter sensing, which supports applications in biomedical, agricultural and electronic manufacturing fields. Full article

Polyethylene (PE) microplastics are increasingly recognized as a critical environmental and food-safety concern; however, routine monitoring remains limited by conventional methods that are labor-intensive, time-consuming, and difficult to translate into rapid, on-site screening. Here, we report a machine learning-guided electrochemical fingerprinting platform for rapid PE microplastic detection using a chitosan–PE interfacial film coupled with electrochemical impedance spectroscopy (EIS) and coulometry. The platform generated concentration-dependent electrical fingerprints in artificial ocean water, captured through Bode, Nyquist, and charge–time responses. Quantification was achieved across 1–256 ng/mL with strong linearity (R² = 0.976) and an ultralow LoD of 0.1 ng/mL, demonstrating high analytical sensitivity. Practical applicability was validated through spike–recovery in ocean water (R² = 0.967) and shrimp-derived matrices with matrix-matched normalization, yielding recoveries of 90–105% across low, mid, and high spike levels. Under the tested particle set, PE produced stronger responses than non-target polypropylene (PP) and polystyrene (PS), supporting empirical polymer discrimination. Machine learning classification using impedance-derived features achieved an AUC = 0.98, with 100% correct identification of Low and 95.24% correct identification of High samples. Overall, this electrochemical–ML framework enables rapid, sensitive, and matrix-tolerant PE microplastic screening in environmental water and seafood-related matrices, offering a promising pathway toward portable microplastic monitoring. Full article

This study developed high-oxygen-barrier active bilayer packaging films by combining corona-treated low-density polyethylene (LDPE) with chitosan/glycerol (CS/Gl) and carvacrol@natural zeolite (CV@NZ) nanohybrid layers using industrially scalable processes. LDPE film was surface-activated via ambient-pressure corona treatment (0.75 s/cm² at 45 kV, 30 W) and assembled with solution-cast CS/Gl or CS/Gl/CV@NZ monolayers via hot-pressing (110 °C, 1 min). Corona treatment enabled robust interfacial adhesion, evidenced by statistical equivalence between monolayer and bilayer mechanical properties. Incorporation of 10 wt.% CV@NZ nanohybrid increased elastic modulus by 60% (to ≈2970 MPa) and tensile strength by 30% (to ≈50 MPa). The LDPE-CS/Gl film achieved a 64-fold reduction in oxygen permeability; CV@NZ incorporation maintained excellent barrier performance (22-fold reduction). Antioxidant potency increased 16-fold upon CV@NZ incorporation. The LDPE-CS/Gl/CV@NZ film demonstrated exceptional antibacterial activity (5.08–5.30 log reductions; >99.999% kill) against both Listeria monocytogenes and Escherichia coli—substantially exceeding additive effects—confirming synergistic action between chitosan and carvacrol. In fresh minced pork preservation (8 days, 4 °C), the active film achieved a 1.73 log reduction in Total Viable Count (98.2% inhibition) and extended microbiological shelf life from 6 to beyond 8 days (33% increase). The bilayer configuration utilizes only 40% of the total thickness as biopolymer, aligning with circular economy principles. Unlike conventional high-barrier films (e.g., PA/PE) which require complex compatibilization for recycling, the water-soluble chitosan layer in this bilayer design can be readily separated from the LDPE backbone, enabling recovery of a pure polymer stream. This work demonstrates a feasible pathway for developing next-generation active packaging that combines a high oxygen barrier, potent antioxidant activity, and exceptional antimicrobial efficacy through industrially scalable manufacturing. Full article

The growing environmental plastic pollution triggered research for biodegradable and safe materials, among which biopolymer-based films stand as the most promising. Among these, chitosan has gained significant attention due to its biocompatibility, film-forming ability, and inherent antimicrobial properties. In this context, the use of fillers to design chitosan nanocomposite films has been shown to enhance the mechanical, barrier, thermal, optical, and antimicrobial properties of the resulting bioplastics. However, the fate and destiny of these fillers, as well as their impact on the biological properties and biodegradability of chitosan films, remain underexplored. We herein report a more comprehensive screening of a set of fillers, encompassing three clay variants (montmorillonite, sepiolite, and halloysite) and microcrystalline chitin. The films were systematically characterized to assess their antibacterial performance, cytocompatibility, hemocompatibility, and biodegradability. The highest antibacterial activity was observed for CS@MMT-f film towards Staphylococcus aureus and Escherichia coli. Importantly, all developed films demonstrated negligible hemolytic activity and low cytotoxicity, indicating their safety for potential biomedical or food-contact applications. Moreover, the selected films completely degrade within four to six weeks under soil burial conditions, demonstrating their potential as environmentally friendly packaging materials. Full article

Hydrocolloids comprise a diverse class of high-molecular-weight polymeric carbohydrates associated with a wide range of physicochemical and functional properties. This review provides an integrated analysis of natural hydrocolloids derived from algal (agar, alginate, carrageenan, fucoidan, laminarin, and ulvan), animal (chitin, chitosan, chondroitin sulfate, dermatan sulfate, keratan sulfate, heparin, heparan sulfate, glycogen, and hyaluronan), and plant (pectin, starch, and locust bean gum) sources, together with semisynthetic cellulose-based derivatives. Emphasis is placed on the relationship between molecular structure, charge density, sulfation patter, and branching degree, and how these parameters modulate hydration, gelation, and rheological behavior. Comparative analyses are presented, establishing structure–function interactions that link molecular characteristics to functional properties, including thickening, gelling, emulsifying, stabilizing, film-forming, and controlled-release capacities. The review also discusses the biological activities and application potential of these hydrocolloids in pharmaceutical, biomedical, and advanced material systems. In addition, emerging modification strategies, including chemical functionalization, crosslinking, and nanostructuring are discussed as tools to adjust their action and diversify their application range. Special attention is given to structure–rheology–gelation relationships and to the influence of molecular organization on mechanical strength, stability, and delivery performance. Current challenges associated with scalability, processability, reproducibility, and long-term functional stability are also critically discussed. Overall, this review provides a comprehensive structure–function perspective on hydrocolloids as sustainable and multifunctional polymeric materials, supporting their rational design and continued development in pharmaceutical sciences, biomedical engineering, and advanced material applications. Full article

Chitosan-based copper composites have attracted considerable interest for biomedical and antimicrobial uses due to their biocompatibility, adjustable dielectric characteristics, and ion-mediated antimicrobial effectiveness. In this study, chitosan films doped with Cu(NO₃)₂, containing 3, 6, and 9 wt% of copper nitrate were produced using a solution-casting method at room temperature. This was done to explore the relationship between structural interactions, dielectric relaxation, optical properties, and antimicrobial efficacy. The resulting composite has been investigated physically using FTIR, XRD, optical analysis, and dielectric spectroscopy, and biologically for its antimicrobial activity. FTIR revealed the molecular structure of Cs-Cu(NO₃)₂ and changes resulting from new bond(s) formation and/or decomposition. XRD indicated that there are no peaks assigned for CuO, which weakens the composite antimicrobial activity. Optical analysis showed an increase in the band gap with copper (II) nitrate concentration over 3%. Additionally, the electrical impedance of the resulting composite increased by approximately one decade. A detailed electrical analysis of the charge-carrier types is provided. Moreover, the antimicrobial activity of chitosan is slightly enhanced by the additive copper (II) nitrate in a dose-dependent manner. The current research offers a mechanistic understanding of the structure–property relationships that govern the behavior of Cu(NO₃)₂–chitosan composites, emphasizing the significant influence of processing conditions on adapting of their dielectric and biological properties. Full article

In the present study, innovative active gelatin–chitosan films enriched with blackberry (ACTIVE-BF) and sage flower (ACTIVE-SF) extracts were developed and comprehensively characterised with regard to their physicochemical, functional and environmental properties. The incorporation of phenolic compounds increased the film’s UV–Vis (ultraviolet–visible spectroscopy) absorbance, confirming the presence of chromophoric groups and the improvement of light-barrier properties. FTIR (Fourier Transform Infrared Spectroscopy) analysis revealed hydrogen bond formation and intermolecular interactions between polyphenols and the –OH/–NH groups of the biopolymer matrix, which enhanced the structural stability of the films. Adding blackberry and sage extracts slightly increased the hydrophilicity and solubility of the films (40–48%), without significantly affecting their water vapour transmission rate (531–547 g/m²·d). The obtained films exhibited strong antioxidant activity, with FRAP (Ferric Reducing Antioxidant Power) values ranging from 17.75 to 40.83 mM Trolox/mg, DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging capacity between 42.58 and 46.88%, and metal chelating ability up to 50.82%. During the nine-day storage of salmon fillets at 4 °C, the active films effectively inhibited microbial growth (reduction of 1.5–2.1 log CFU/g) while maintaining pH stability (6.2–6.4). Respiration activity confirmed environmental safety. The developed materials represent biodegradable, multifunctional films with high potential for application as sustainable active packaging for perishable food products. Full article

The aim of this study was to use lemon balm extract (Melissa officinalis L.), prepared via microwave-assisted extraction, for the development of novel formulations of functional edible films based on chitosan, gum arabic, and gelatine (simple and blended formulations). This study focused on changes in the antioxidant properties of enriched films, in addition to their physicochemical and barrier performance for potential applications. Thickness, colour, transparency, water solubility, gas and water vapour permeability, total polyphenol content, and antioxidant capacity were evaluated. The addition of lemon balm extract resulted in an increased polyphenol content (of about 30%) and enhanced antioxidant properties (approximately three-fold), without influencing hydration-related properties (solubility, moisture content and water absorption). These parameters were significantly influenced by the matrix structure (neat chitosan vs. blends with gelatine and gum arabic). Significant increases in the oxygen (three-fold for neat chitosan and five-fold for blends) and carbon dioxide (21-fold for blends) permeability coefficients were also observed in all films with extracts. However, all values remained below 30 × 10⁻⁵ cm³ m⁻¹ d⁻¹ bar⁻¹, indicating that all films retained good gas barrier properties. The results indicate the potential of the developed material for applications in active food packaging as a sustainable alternative to traditional packaging materials, which should be further validated through studies on real food systems and shelf-life evaluation. Full article

This paper highlights the importance of chitosan’s intrinsic parameters on its performance as a film. Fungal (FC) and crustacean (CSC) chitosans with similar molecular weight (400 kDa) and different deacetylation degrees (FC DDA = 84.2%; CSC DDA ≈ 75%) were utilized to elaborate eco-friendly and functional chitosan-based films (C-films). The physicochemical properties as well as bioactivities were evaluated. Results showed that DDA was positively correlated with the zeta potential of the film-forming solutions. Furthermore, the FC films showed a decrease in moisture and swelling levels by about 20%, accompanied by a slight drop in qualitative hydrophobicity. On the other hand, the antibacterial activity of FC film was significantly stronger against Gram-negative bacteria compared to CSC film. Additionally, the C-films considerably mitigated the adherence of Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli, where the percentage of the covered surface ranged from 0.5 to 24%. Conversely, Enterococcus faecalis was more resistant, with percentages of the covered surface higher than 50%. Nonetheless, disintegration in cell structure was noticed regarding the CSC film. Ultimately, the theoretical prediction of cell adherence was highly correlated with experimental results (r = −0.89). These promising results demonstrate that C-films with high DDA are excellent candidates for preventing biofilm formation. Full article