Characterization and antimicrobial analysis of chitosan-based films

Mechanical, morphological, thermal, and fire-retardant properties of sustainable chitosan-lignin based bioplastics

Lignin can function as a fire retardant for biocomposites because of its excellent thermal stability. This work evaluated the impact of integrating technical lignin into chitosan-based bioplastics to enhance their mechanical and thermal properties. The solvent-casting technique was employed for the preparation of chitosan-lignin bioplastics. The incorporation of lignin improved the antioxidant properties and mechanical strength of the bioplastic, and it functions as a UV-blocking agent, as evidenced by UV-shielding studies, which indicates a reduction in the transmittance of the chitosan-lignin bioplastic by approximately four fold. The incorporation of lignin washed 3× with HCl into the chitosan-based bioplastic increased the tensile strength of the material by 36.41 % and the elastic modulus by 56.04 %. The antioxidant activity of the chitosan-lignin-based bioplastic ranged from 75.80 % to 80.38 %, whereas that of neat chitosan was only 25.02 %. Thermal analysis revealed that incorporating lignin as an additive in a chitosan-based bioplastic improved the thermal stability and flame retardancy of the bioplastic. This is indicated by a higher limiting oxygen index (LOI) value ranging from 42 to 48 % for the chitosan-lignin bioplastics than for the control bioplastic (27 %), which has a UL-94 rating in the V-0 range. These findings support the fact that the antioxidant, strength, and fire-retardant performance of chitosan-based bioplastics could be enhanced by the addition of lignin.

Fluorescent Self-Supporting Composite Film Formed from Chitosan and the Neutral Poly(3-hexylthiophene-co-1,4-phenylene) Polymer with Enhanced Dispersion Properties for a Small Molecule

A composite film of chitosan (Ch) with a neutral conjugated polymer, poly(3-hexylthiophene-co-1,4-phenylene) (PTPh), was developed to combine the adsorption capacity of Ch with the fluorescence sensitivity of PTPh. Characterization of the films using thermogravimetric analysis, microscopy, and infrared, absorption, and fluorescence spectroscopies revealed that the dispersity of the target small molecule, 4-aminoazobenzene (4-AAB), was improved in the composite film compared to the pristine Ch film as evidenced in microscopy studies. In the presence of 4-AAB, the Ch/PTPh film exhibited fluorescence quenching at low 4-AAB concentrations and changes in emission spectra at higher concentrations. Photoisomerization studies suggested that the improved dispersity of 4-AAB in the composite film is due to an increase in the free volume provided by PTPh, with faster cis-to-trans isomerization observed when PTPh was present. Proof-of-concept adsorption experiments showed that the composite film adsorbed 4-AAB from an aqueous solution, leading to a change in the emission properties of the film. This qualitative characterization uncovered a dual role for the conjugated polymer in the composite film: the addition of the polymer changed the morphology and robustness of the film, and the polymer also provides the fluorophore to sense adsorbed molecules over a wide range of 4-AAB concentrations. These results show that the strategy of incorporating water-insoluble polymers at low concentrations into a versatile biopolymer leads to enhanced functionalities of a composite material.

Antimicrobial chitosan-based hydrogels: A novel approach to obtain sanitizers

The study presents novel hydrogels obtained by crosslinking chitosan with both furfural and glutaraldehyde via dynamic imine bonds. Scanning electron microscopy confirmed the formation of porous networks with a mean diameter of the pores between 15 and 35 μm, while the supramolecular characterization by polarized optical microscopy and wide-angle X-ray diffraction proved the gelation mechanism. The hydrogels presented great rheological properties, along with an anti-creep behavior. The resulting materials were highly adhesive and had great antioxidant activity, leading to an inhibition of 78 % of DPPH free radicals, and exhibiting antimicrobial activity against Gram-positive and Gram-negative bacteria and fungi, reaching a maximum of the diameter of the inhibition zone of 31 mm against Candida albicans. The MTS assay, performed on NHDF cells confirmed the non-toxicity of the hydrogels, the viability of the cells remaining at values higher than 90 % for all samples, revealing their potential for bioapplications. In vitro release studies of the furfural monoaldehyde showed distinct release kinetics for each hydrogel, emphasizing their versatility. Fitting the data on different mathematical models indicated a diffusion-controlled release mechanism during the entire release process. All these findings highlighted the potential of these hydrogels to be used as biocidal agents for topical applications.

Advanced antimicrobial surfaces in cellulose-based food packaging

This critical review provides a comprehensive framework for selecting engineered colloidal and nanostructured systems for cellulose-based food packaging. Meta-analysis was used as a methodological approach to categorize them according to antimicrobial agents, coating methods, and synergistic effects against a broad spectrum of microorganisms. The most frequent substrate is flexible packaging paper (35-70 g/m2, uncalendered), often intended for food wrapping. Among antimicrobial agents, chitosan-based coatings are a common choice-often combined with essential oils-being particularly effective against Gram-positive bacteria (e.g., Staphylococcus aureus, Listeria monocytogenes, Bacillus subtilis). This is attributed to electrostatic interactions between the polysaccharide's protonated -NH3+ groups and teichoic acids within bacterial cell walls. Inorganic metal nanoparticles, such as ZnO nanorods and Ag nanoparticles, are broadly effective by compromising the membranes of various foodborne pathogens-including Bacillus cereus and Pseudomonas aeruginosa. Terpenoid- or phenolic-rich essential oils-commonly delivered in emulsions or encapsulated in host-guest β-cyclodextrin complexes-inhibit the growth of yeasts and molds, besides some common bacteria when grafted onto bleached paper. Synergistic effects have been observed with complex coatings such as chitosan combined with CuONPs. Despite their promising performance, the widespread industrial adoption of cellulose-based active packaging in the food sector requires addressing not only antimicrobial activity, but also barrier properties and feasible methods to functionalize the paper surface (e.g., bar coating). These challenges, often overlooked, are critically assessed herein. All considered, further studies are required to address the challenges of cellulosic antimicrobial materials in a holistic manner to accelerate its large-scale implementation in the food sector.

Development and antimicrobial activity of composite edible films of chitosan and nisin incorporated with perilla essential oil-glycerol monolaurate emulsions

Aquatic products are highly susceptible to spoilage, and preparing composite edible film with essential oil is an effective solution. In this study, composite edible films were prepared using perilla essential oil (PEO)-glycerol monolaurate emulsions incorporated with chitosan and nisin, and the film formulation was optimized by response surface methodology. These films were applied to ready-to-eat fish balls and evaluated over a period of 12 days. The films with the highest inhibition rate against Staphylococcus aureus were acquired using a polymer composition of 6 μL/mL PEO, 18.4 μg/mL glycerol monolaurate, 14.2 mg/mL chitosan, and 11.0 μg/mL nisin. The fish balls coated with the optimal edible film showed minimal changes in appearance during storage and significantly reduced total bacterial counts and total volatile basic nitrogen compared to the control groups. This work indicated that the composite edible films containing essential oils possess ideal properties as antimicrobial packaging materials for aquatic foods.

Atmosphere-controlled high-voltage electrospray for improving conductivity, flexibility, and antibacterial properties of chitosan films

Atmosphere-controlled high-voltage electrospray (AHES) was utilised to modify the structure of chitosan (CS) films. The applied voltage in the AHES process ranged from 60 to 100 kV, with variations in the O2 content of the propellant gas from 0 to 100 %. The number density of cations in the charging environment reached 600 × 105 cations/cm3. Under these specific conditions, the one-step AHES procedure facilitated the protonation of the amine groups in the CS molecular chains, resulting in a notable increase in electrical conductivity by over 95 % and tensile elongation by over 100 %. The generation of reactive oxygen species during the AHES process also improved the antibacterial properties of the charged CS films, as evidenced by a more than 36 % increase in the inhibition zone diameter. The treated (AHES) films were employed for preserving fresh-cut muskmelon slices. These films maintained satisfactory sensory quality and effectively controlled water evaporation for up to 3 days when utilised as the inner layer of the packaging. These enhancements were achieved through a single-step AHES treatment, without the addition of chemicals or the need to alter the ambient temperature (25 °C ± 5°C). Consequently, AHES presents itself as a viable method for modifying the electrostatic characteristics of CS films and can be extended to various other materials.

Co-assembled biomimetic fibrils from collagen and chitosan for performance-enhancing hemostatic dressing

The development of safe and efficient hemostatic materials is medically important to prevent death due to trauma bleeding. Exploiting the synergistic effect between the D-periodic functional domain of collagen fibrils on platelet activation and cationic chitosan on erythrocyte aggregation is expected to develop performance-enhanced hemostatic materials. In this study, we prepared collagen fibrils and chitosan composite hemostatic materials by modulating the self-assembled bionic fibrillation of collagen with different degrees of deacetylation (DD, 50%, 70% and 85%) of chitosan. The findings indicated that chitosan promoted collagen self-assembly, with all the collagen fibrils demonstrating a typical D-periodical structure similar to that of the native collagen. Furthermore, the composite demonstrated enhanced structural integrity and procoagulant capacity along with good biocompatibility. Notably, the fibrillar composites with 70% DD of chitosan exhibited optimal mechanical properties, procoagulant activity, and adhesion of erythrocytes and platelets. Compared to pure collagen fibrils and the commercial hemostatic agent Celox™, the collagen/chitosan fibrillar composite treatment significantly accelerated hemostasis in the rat tail amputation model and liver injury model. This research offers new insights into the development of hemostatic materials and indicates that collagen-chitosan composites hold promising potential for clinical applications.

A response surface methodology study on the development of pH-sensitive wound dressings using Rhodamine B-loaded chitosan nanoparticles and sodium alginate-based films

Purpose

This study aimed to develop an innovative, intelligent wound dressing capable of signaling infections through color changes.

Design/methodology/approach

Using response surface methodology, the Rhodamine B fluorescence colorant was encapsulated within colloidal nanoparticles and integrated into a sodium alginate patch at various concentrations. The physical and chemical characteristics of the nanoparticles and the wound dressing were thoroughly analyzed via dynamic light scattering (DLS), zeta potential measurements, scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). Additionally, the biodegradability, hydrophilicity, swelling behavior, release kinetics, porosity, mechanical properties, biocompatibility, and infection detection capability of the wound dressing were evaluated.

Findings

The results indicated that the average diameter of the synthesized colloidal nanoparticles was 300 nm before loading with Rhodamine B and increased to 400 nm after loading, with zeta potentials of 52 mV and -6 mV, respectively. The Rhodamine B-loaded wound dressing demonstrated adequate levels of swelling and hydrophilicity. Release studies revealed the gradual release of Rhodamine B at low pH. Cytotoxicity assays confirmed the high biocompatibility of the engineered wound dressing with the L929 cell line. Furthermore, bacterial exposure experiments indicated that the color change was activated in the presence of infection, making it visible under UV-A light.

Originality/value

This research presents a novel approach to wound care by developing a smart wound dressing that can detect infections via color changes. These findings underscore the potential of this innovative wound dressing to improve infection management in clinical settings through its responsive and biocompatible design.

Lycopene-Loaded Emulsions: Chitosan Versus Non-Ionic Surfactants as Stabilizers

Lycopene is a natural carotenoid with well-known benefits due to its antioxidant properties, including an anti-inflammatory effect in colorectal cancer and anti-angiogenic effects along with a reduction in the risk of prostate cancer and coronary heart disease. Due to their poor water solubility, photosensitivity and heat sensitivity, their incorporation in cosmetic and food matrices should be through encapsulation systems. In the present work, lycopene-loaded emulsions were prepared using two different types of stabilizers: non-ionic surfactants, testing several ratios of Tween 80 and Span 80, and chitosan, using chitosans of different viscosities and molecular weights. Soybean oil was found to be a suitable candidate for O/W emulsion preparation. Lycopene encapsulation efficiency (EE) of 70-75% and loading capacities of 0.14 mg/g were registered in stable emulsions stabilized either by non-ionic surfactants or acidified chitosans. Therefore, chitosan is a good alternative as a sustainable stabilizer to partially replace traditional synthetic ingredients with a new biodegradable, renewable and biocompatible material which could contribute to reduce the environmental impact as well as the ingestion of synthetic toxic materials by humans, decreasing their risk of suffering from chronic and complex pathologies, among which several types of cancer stand out.

Preparation and characterization of structural and antifouling properties of chitosan/polyethylene oxide membranes

It aims to prepare the chitosan (CS) and polyethylene oxide (PEO) hydrogel membranes with different CS/PEO blend ratios (100:0, 95:5, 90:10, 80:20 and 70:30) via solvent casting. The physicochemical properties of these membranes were investigated using various characterization techniques: Fourier Transform Infrared Spectroscopy (FTIR), X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray (EDX), contact angle, and tensile testing. The interaction of PEO and chitosan was investigated by DSC in terms of freezing bound, freezing free, and non-freezing PEO fraction. The cross-sectional surface morphology of membranes displayed a smoother surface with increasing PEO content up to 20 %, beyond which nonhomogeneity on the surface was visible. The antifouling behavior of membranes was investigated by bacterial adherence study, which showed an enhanced antifouling nature of membranes with the increase in the PEO content. The peeling strength of the membranes was measured using a 90° angle peeling test, and it was found that 20 % and more PEO content promotes easy removal from the gelatin slab. In addition to this, live/ dead assay of the CS was performed to visualize the presence of live and dead bacteria on the surface. The CS/PEO blend with 20 % PEO content has properties makes it suitable for use as a protective layer on wound dressings to prevent bacterial growth. It's use in wound dressings has the potential to reduce the pain during the time of dressing removal and improve patient outcomes. The present investigation leads to the development of a CS hydrogel matrix which exhibits very interesting interaction with the PEO moiety along with its innovative feature of antifouling and antimicrobial nature.

Development of active chitosan film containing bacterial cellulose nanofibers and silver nanoparticles for bread packaging

The objective was to develop an active chitosan-based coating and to evaluate its effect on the shelf life and microbial safety of bread. Bacterial cellulose nanofibers (BCNF) and various levels (0.5%, 1%, and 2%) of silver nanoparticles (AgNPs) were in the chitosan (CS) film. Characterization of films was determined by analyzing WVP, ultraviolet barrier, and opacity as well as FTIR, XRD, DSC, TGA, and SEM. The water vapor permeability (WVP) of CS was remarkably (p < .05) decreased from 3.75 × 10-10 to 0.85 × 10-10 g/smPa when filled with BCNF and 2% AgNPs. Thermal and structural properties were enhanced in nanoparticle-included films. Applying CS/BCNF/AgNPs coatings for bread samples demonstrated a significant improvement in moisture retention and a decrease in the hardness (from 10.2 to 7.05 N for CS and CS/BCNF/1% AgNPs coated samples, respectively). Moreover, microbial shelf life of bread sample increased from 5 to 38 days after packaging with CS/BCNF/2% AgNPs film. After a storage period of 15 days at 25°C, no fungal growth was detected in bread samples which were coated with nanocomposite suspensions containing 1% and 2% AgNPs. However, at the same condition, yeast and mold counts was 7.91 log CFU/g for control sample. In conclusion, the CS/BCNF/2% AgNPs film might have the potential for use as active packaging of bread.

Valorization of Seafood Waste for Food Packaging Development

Packaging plays a crucial role in protecting food by providing excellent mechanical properties as well as effectively blocking water vapor, oxygen, oil, and other contaminants. The low degradation of widely used petroleum-based plastics leads to environmental pollution and poses health risks. This has drawn interest in renewable biopolymers as sustainable alternatives. The seafood industry generates significant waste that is rich in bioactive substances like chitin, chitosan, gelatins, and alginate, which can replace synthetic polymers in food packaging. Although biopolymers offer biodegradability, biocompatibility, and non-toxicity, their films often lack mechanical and barrier properties compared with synthetic polymer films. This comprehensive review discusses the chemical structure, characteristics, and extraction methods of biopolymers derived from seafood waste and their usage in the packaging area as reinforcement or base materials to guide researchers toward successful plastics replacement and commercialization. Our review highlights recent advancements in improving the thermal durability, mechanical strength, and barrier properties of seafood waste-derived packaging, explores the mechanisms behind these improvements, and briefly mentions the antimicrobial activities and mechanisms gained from these biopolymers. In addition, the remaining challenges and future directions for using seafood waste-derived biopolymers for packaging are discussed. This review aims to guide ongoing efforts to develop seafood waste-derived biopolymer films that can ultimately replace traditional plastic packaging.

Novel chitosan-based smart bio-nanocomposite films incorporating TiO2 nanoparticles for white bread preservation

Chitosan (CS)-based bio-nanocomposite food packaging films were prepared via solvent-casting method by incorporating a unique combination of additives and fillers, including polyvinyl alcohol (PVA), glycerol, Tween 80, castor oil (CO), and nano titanium dioxide (TiO2) in various proportions to enhance film properties. For a comprehensive analysis of the synthesized films, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), thermogravimetric analysis (TGA), tensile testing, field emission scanning electron microscopy (FESEM), energy dispersive X-ray spectroscopy (EDS), and UV-vis spectrophotometry were employed. Furthermore, the antimicrobial efficacy of the films against S. aureus, E. coli, and A. niger was examined to assess their potential to preserve food from foodborne pathogens. The results claimed that the inclusion of castor oil and TiO2 nanoparticles considerably improved antimicrobial properties, UV-vis light barrier properties, thermal stability, optical transparency, and mechanical strength of the films, while reducing their water solubility, moisture content, water vapor and oxygen permeability. Based on the overall analysis, CS/PVA/CO/TiO2-0.3 film can be selected as the optimal one for practical applications. Furthermore, the practical application of the optimum film was evaluated using white bread as a model food product. The modified film successfully extended the shelf life of bread to 10 days, surpassing the performance of commercial LDPE packaging (6 days), and showed promising attributes for applications in the food packaging sector. These films exhibit superior antimicrobial properties, improved mechanical strength, and extended shelf life for food products, marking a sustainable and efficient alternative to conventional plastic packaging in both scientific research and industrial applications.

Chitosan nanofiber paper used as separator for high performance and sustainable lithium-ion batteries

Separators are indispensable components in lithium-ion batteries (LIBs), providing efficient pathways for lithium ions to travel and isolating the positive and negative electrodes to avoid short circuits. However, traditional polyolefin-based separators exhibit inferior electrolyte affinities, limited porosities, and low thermal stabilities. In this study, a novel method was developed to prepare chitosan micro/nanofiber membranes as LIB separators using natural materials. The pore sizes of the chitosan micro/nanofibers separators were modulated by changing the diameters of the chitosan fibers. The results demonstrated that the chitosan nanofiber separators (CSNFs) had superior electrolyte uptake (281 %), excellent thermal dimensional stability, and electrochemical performance in LiFePO4/Li half-cell, as indicated by the higher discharge capacity after 100 cycles, and higher rate capacity than commercial Celgard2325 separator. This study paves the way for the fabrication of eco-efficient and environment-friendly separators for high-performance LIBs.

UV- shielding and antioxidant properties of chitosan film impregnated with Acacia catechu modified with calcium carbonate for food packaging

Acacia catechu contains polyphenolic compounds such as catechin and tannins, which exhibit antioxidant and antimicrobial properties that have the potential to be used in food packaging applications. In this study, chitosan-based (CH) antioxidant films were developed with the incorporation of calcium carbonate (CC) and Acacia catechu (CT). The films were fabricated by the solvent-casting method, and the effects of the different concentrations of Acacia catechu were analyzed. The physicomechanical, antioxidant, and UV shielding properties of the films were determined. The addition of Acacia catechu and calcium carbonate has significantly increased the tensile from 2.30 MPa to 4.95 MPa, respectively, for neat CH and CH/CC/CT-4 film. At the same time, there is a reduction in the elongation at break from 26.75 % in neat CH film to 12.11 % in CH/CC/CT-4 film. The CH/CC/CT-4 film has shown the highest ferric-reducing antioxidant power (FRAP) of 0.440 mg Trolox/g dried weight of the film and 2,2 diphenyl picrylhydrazyl (DPPH) radical scavenging activity of 93.05 %. The UV transmittance of CH/CC/CT-4 film was 0.46 %, the lowest compared to the rest of the fabricated films. These active properties depict that CH/CC/CT-4 film has the potential to be utilized for the packaging of light and oxygen-sensitive food products.

Aloe vera/Chitosan-Based Edible Film with Enhanced Antioxidant, Antimicrobial, Thermal, and Barrier Properties for Sustainable Food Preservation

Food bioactive packaging has received increasing attention from consumers and the food industry for its potential to reduce food waste and environmental issues. Several materials can be used to produce edible films/coats; however, bio-based, cost-effective, and sustainable coatings have gained a high reputation these days. For instance, Aloe vera gel (AV) is a promising bio-based material for edible coatings and films; therefore, the present study aimed to investigate the film-forming abilities of AV and Chitosan (CH) combination as a potential active food packaging material. The physicochemical and mechanical characteristics of formed films of various combinations were prepared at different concentrations, i.e., CH (0.5% w/v), AV (100%), CH:AV (75:25), and CH:AV (60:40). The results showed significant differences among all the prepared edible films wherein these differences were mainly on account of incorporating AV gel. The rheological and antioxidant properties of the formulations improved with the inclusion of AV gel. The films composed of CH:AV (60:40) positively affected the water solubility, thermal properties, and water vapour permeability of the edible films. The X-ray Diffraction (XRD) and Scanning electron microscopy (SEM) results showed that the films composed of CH:AV, (60:40) were amorphous and had smooth morphology. Further, the edible film solutions were applied to fresh figs (Ficus carica) to investigate their role in preserving fruits during storage. A significant reduction in microbial growth was found in coated fruits after 28 days of cold storage. The films composed of CH and AV showed overall improved results compared to the CH (0.5%, w/v). Therefore, the used formulations (CH:AV, 60:40) can form a sustainable film that has the potential to be utilized for fresh product preservation to maintain its quality and shelf life.

Construction of a multifunctional dual-network chitosan composite aerogel with enhanced tunability

Typically, the tailorable versatility of biomass aerogels is attributed to the tunable internal molecular structure, providing broad application prospects. Herein, a simple and novel preparation strategy for developing multifunctional dual-network chitosan/itaconic acid (CSI) aerogel with tunability by using freeze-drying and vacuum heat treatment techniques. By regulating the temperature and duration of amidation reaction, electrostatic interactions between chitosan (CS) and itaconic acid (IA) was abstemiously converted into amide bond in frozen aerogel, with IA acting as an efficient in-situ cross-linking agent, which yielded CSI aerogels with different electrostatic/covalent cross-linking ratios. Heat treatment and tuning of the covalent cross-linking degree of CSI aerogel changed their microstructure and density, which led to enhanced performance. For example, the specific modulus of CSI1.5-160 °C-5 h (71.69 ± 2.55 MPa·cm3·g-1) increased by 119 % compared to that of CSI1.5 (32.73 ± 0.718 MPa·cm3·g-1), converting the material from superhydrophilic to hydrophobic (124° ± 3.6°), exhibiting favorable stability and heat transfer performance. In addition, part of -NH3+ of CS was retained in the electrostatic cross-linked network, endowing the aerogel with antibacterial properties. The findings of this study provide insights and a reliable strategy for fabricating biomass aerogel with good comprehensive performance via ingenious structural design and simple regulation methods.

Antimicrobial peptides grafted onto the surface of N-acetylcysteine-chitosan nanoparticles can revitalize drugs against clinical isolates of Mycobacterium tuberculosis

Tuberculosis is caused by Mycobacterium tuberculosis (MTB) and is the leading cause of death from infectious diseases in the World. The search for new antituberculosis drugs is a high priority, since several drug-resistant TB-strains have emerged. Many nanotechnology strategies are being explored to repurpose or revive drugs. An interesting approach is to graft antimicrobial peptides (AMPs) to antibiotic-loaded nanoparticles. The objective of the present work was to determine the anti-MTB activity of rifampicin-loaded N-acetylcysteine-chitosan-based nanoparticles (NPs), conjugated with the AMP Ctx(Ile21)-Ha; against clinical isolates (multi- and extensively-drug resistant) and the H37Rv strain. The modified chitosan and drug-loaded NPs were characterized with respect to their physicochemical stability and their antimycobacterial profile, which showed potent inhibition (MIC values <0.977 μg/mL) by the latter. Furthermore, their accumulation within macrophages and cytotoxicity were determined. To understand the possible mechanisms of action, an in silico study of the peptide against MTB membrane receptors was performed. The results presented herein demonstrate that antibiotic-loaded NPs grafted with an AMP can be a powerful tool for revitalizing drugs against multidrug-resistant M. tuberculosis strains, by launching multiple attacks against MTB. This approach could potentially serve as a novel treatment strategy for various long-term diseases requiring extended treatment periods.

Development and properties of biodegradable film from peach palm (Bactris gasipaes)

Formulations of biodegradable films using macrocarpa peach palm flour (low amylose starch), chitosan and glycerol, were developed and the effects of the drying temperature on films by assessing their physicochemical, mechanical, barrier, optical, structural, antioxidant properties, and the biodegradability in soil were evaluated. Chitosan enhanced the mechanical properties of the films, but they showed no antimicrobial activity against the tested food-borne pathogens, except for Listeria monocytogenes, for which the inhibition zone was from 0.1 to 0.6 cm. Films with higher concentrations of peach palm flour are opaquer, with better antioxidant characteristics and content of phenolic compounds compared to films made with lower concentrations of flour. The films presented a yellowish color because of the carotenoids found in peach palm flour, 29.63 μg 100 g-1, and exhibited a C-type X-ray pattern, characteristic peak of materials where amylose and amylopectin are present. After 15 days in soil, the films lost 30% of their initial weight. Therefore, these results suggest that the development of films as food preservative is a promising field and that the material used in the study are suitable for their formulation.

Vanillin Cross-Linked Chitosan Film with Controlled Release of Green Tea Polyphenols for Active Food Packaging

We report a novel cross-linked chitosan composite film containing vanillin, glycerol, and green tea extract. The effects of vanillin-mediated cross-linking and the incorporation of antimicrobial green tea polyphenols were investigated. The cross-linking effect, confirmed by Fourier transform infrared (FTIR) analysis, increased the tensile strength of the biopolymer film to 20.9 ± 3 MPa. The release kinetics of polyphenols from the chitosan-vanillin matrix was studied, and we reported an initial burst release (8 h) followed by controlled release (8 to 400 h). It was found that both vanillin and green tea polyphenols were successful inhibitors of foodborne bacteria, with a minimum inhibitory concentration of the tea polyphenols determined as 0.15 mg/mL (Staphylococcus aureus). These active components also displayed strong antioxidant capacities, with polyphenols quenching >80% of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radicals at all concentrations tested. Degradation results revealed that there was a significant (>85%) mass loss of all samples after being buried in compost for 12 weeks. The biopolymeric films, prepared by solvent casting methods, adhere to green chemistry and waste valorization principles. The one-pot recipe reported may also be applied to other cross-linkers and active compounds with similar chemical functionalities. Based on the obtained results, the presented material provides a promising starting point for the development of a degradable active packaging material.

An insight on sources and biodegradation of bioplastics: a review

Durability and affordability are two main reasons for the widespread consumption of plastic in the world. However, the inability of these materials to undergo degradation has become a significant threat to the environment and human health To address this issue, bioplastics have emerged as a promising alternative. Bioplastics are obtained from renewable and sustainable biomass and have a lower carbon footprint and emit fewer greenhouse gases than petroleum-based plastics. The use of these bioplastics sourced from renewable biomass can also reduce the dependency on fossil fuels, which are limited in availability. This review provides an elaborate comparison of biodegradation rates of potential bioplastics in soil from various sources such as biomass, microorganisms, and monomers. These bioplastics show great potential as a replacement for conventional plastics due to their biodegradable and diverse properties.

Chitosan-based composite films containing eugenol nanoemulsion, ZnO nanoparticles and Aloe vera gel for active food packaging

Biopolymer-based food packaging films are gaining increasing popularity, as consumers' demands for sustainable alternatives and environmental concerns associated with synthetic plastic packaging grow. In this research work, chitosan-based active antimicrobial films reinforced with eugenol nanoemulsion (EuNE), Aloe vera gel, and zinc oxide nanoparticles (ZnONPs) were fabricated and characterized for their solubility, microstructure, optical properties, antimicrobial and antioxidant activities. The rate of release of EuNE from the fabricated films was also evaluated to determine active nature of the films. The EuNE droplet size was about 200 nm, and they were uniformly distributed throughout the film matrices. Incorporation of EuNE in chitosan drastically improved UV-light barrier property of the fabricated composite film by 3 to 6 folds, while maintaining their transparency. The XRD spectra of the fabricated films showed good compatibility between the chitosan and the incorporated active agents. The incorporation of ZnONPs significantly improved their antibacterial properties against foodborne bacteria and tensile strength about 2-folds, whereas incorporation of EuNE and AVG improved DPPH scavenging activities of the chitosan film up to 95 %, respectively.

Development of composite film based on collagen and phenolic acid-grafted chitosan for food packaging

Collagen, a fibrous protein with triple-helical structure, is a good film-forming substrate for food packaging films because collagen films show advantages of biodegradability, high mechanical strength and good water resistance. However, collagen films lack functional activities, which may limit their applications in the field of active packaging. In this work, phenolic acid-grafted-chitosan was blended with collagen to improve the antioxidant and antimicrobial activities of collagen films. Gallic acid (GA), ferulic acid (FA) and caffeic acid (CA) were respectively grafted onto chitosan, and the physical properties and functional activities of the collagen/phenolic acids-g-chitosan (CGC, CFC and CCC) films were compared. The prepared films presented varying degrees of yellow color, and exhibited significantly improved UV light blocking capacity, antioxidant and antimicrobial properties due to the function of phenolic acid. Moreover, compared with collagen/chitosan (CC) film, CGC, CFC and CCC films showed higher mechanical strength (69.08-73.79 MPa), higher thermal denaturation temperature (69.4-71.2 °C), and lower water vapor permeability values (2.64-2.98 × 10^-12 g m^-1 s^-1 Pa^-1). The properties of collagen/ phenolic acids-g-chitosan films were greatly affected by the type of phenolic acid grafted. CGC film had the best antioxidant property as well as the best mechanical property, thermostability, UV light and water vapor blocking capacity.

Characterization of heat-treated chitosan cast films and their antimicrobial activity on the growth of natural flora of pasteurized milk

This research aimed to evaluate the physicochemical and biocidal properties of chitosan films obtained through the solvent casting method using two different molecular weights, and thermally treated for an extended time (3 weeks) at 70 °C under vacuum condition (RH 0 %). The effect of storage time (for 30 and 180 days) under ambient conditions (23 °C and RH 40 %) on the properties of heat-treated cast films and their biocidal effectiveness was also assessed. FTIR-ATR, TGA and XRD of resulting films were analyzed to explore the dependency of antibacterial performance on the alteration in molecular and chemical structure. The results demonstrated that the solubility of treated films at 70 °C was proportionally reduced, resulting from the reduction of protonated amines and an increase in crystallinity. Likewise, increasing storage time led to a significant lowering in the solubilization of cast films. It was found that the solubilized fraction of chitosan cast films is the active fraction with the biocide behavior that can act against bacteria. In addition, the effectiveness of migrated chitosan was examined against the natural flora of pasteurized milk, such as Paenibacillus and Pseudomonas fluorescens. The results showed that cast films obtained from chitosan with lower molecular weight caused a reduction in the total count of viable cells without a significant effect on the properties of milk.

Chitosan modified with bio-extract as an antibacterial coating with UV filtering feature

Benzophenone-3 grafted chitosan (CS-BP-3) was successfully synthesized and applied as an antibacterial coating for the first time. The grafting mechanism is based on the reaction between ketone and primary amine to form imine derivatives and the chemical structure of grafted chitosan was studied by Fourier transform infrared (FT-IR) spectroscopy. Water solubility of BP-3 is enhanced after covalently grafted on chitosan and consequently renders the chitosan coating with UV blocking property. Results of thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) further confirmed the thermal stability of BP-3 modified chitosan is enhanced. The CS-BP-3 coating was applied on a variety of substrates of glass, plastics, wood, and metal. The surface features of the coatings such as morphology, water contact angle (WCA), and surface roughness were investigated. The optical and thermal stabilities of the coatings under UV irradiation were studied for 16 h. Antibacterial activity of CS-BP-3 was evaluated against both Gram-negative and Gram-positive bacteria. And the results of bacterial inhibition by CS-BP-3 coating indicate its potential for future application in food packaging.

Waste Orange Peels as a Source of Cellulose Nanocrystals and Their Use for the Development of Nanocomposite Films

To date, approximately 30-50% of food is wasted from post-harvesting to consumer usage. Typical examples of food by-products are fruit peels and pomace, seeds, and others. A large part of these matrices is still discarded in landfills, while a small portion is valorized for bioprocessing. In this context, a feasible strategy to valorize food by-products consists of their use for the production of bioactive compounds and nanofillers, which can be further used to functionalize biobased packaging materials. The focus of this research was to create an efficient methodology for the extraction of cellulose from leftover orange peel after juice processing and for its conversion into cellulose nanocrystals (CNCs) for use in bionanocomposite films for packaging materials. Orange CNCs were characterized by TEM and XRD analyses and added as reinforcing agents into chitosan/hydroxypropyl methylcellulose (CS/HPMC) films enriched with lauroyl arginate ethyl (LAE). It was evaluated how CNCs and LAE affected the technical and functional characteristics of CS/HPMC films. CNCs revealed needle-like shapes with an aspect ratio of 12.5, and average length and width of 500 nm and 40 nm, respectively. Scanning electron microscopy and infrared spectroscopy confirmed the high compatibility of the CS/HPMC blend with CNCs and LAE. The inclusion of CNCs increased the films' tensile strength, light barrier, and water vapor barrier properties while reducing their water solubility. The addition of LAE improved the films' flexibility and gave them biocidal efficacy against the main bacterial pathogens that cause foodborne illness, such as Escherichia coli, Pseudomonas fluorescens, Listeria monocytogenes, and Salmonella enterica.

Recovery and Purification of Cutin from Tomato By-Products for Application in Hydrophobic Films

Tomato pomace is a low-cost, renewable resource that has been studied for the extraction of the biopolyester cutin, which is mainly composed of long-chain hydroxy fatty acids. These are excellent building blocks to produce new hydrophobic biopolymers. In this work, the monomers of cutin were extracted and isolated from tomato pomace and utilized to produce cutin-based films. Several strategies for the depolymerization and isolation of monomeric cutin were explored. Strategies differed in the state of the raw material at the beginning of the extraction process, the existence of a tomato peel dewaxing step, the type of solvent used, the type of alkaline hydrolysis, and the isolation method of cutin monomers. These strategies enabled the production of extracts enriched in fatty acids (16-hydroxyhexadecanoic, hexadecanedioic, stearic, and linoleic, among others). Cutin and chitosan-based films were successfully cast from cutin extracts and commercial chitosan. Films were characterized regarding their thickness (0.103 ± 0.004 mm and 0.106 ± 0.005 mm), color, surface morphology, water contact angle (93.37 ± 0.31° and 95.15 ± 0.53°), and water vapor permeability ((3.84 ± 0.39) × 10^-11 mol·m/m²·s·Pa and (4.91 ± 1.33) × 10^-11 mol·m/m²·s·Pa). Cutin and chitosan-based films showed great potential to be used in food packaging and provide an application for tomato processing waste.

Evaluation of a chitosan dressing in the management of hard-to-heal wounds

It is vital that as tissue viability teams, we are constantly striving to improve service delivery, healing rates and positive patient outcomes. In 2021 the author's team were introduced to a unique bioactive microfibre gelling (BMG) dressing, MaxioCel®, which uses chitosan to maintain a cohesive structure to increase fluid handling, antimicrobial and wound-healing properties.

METHOD

Following Isle of Wight NHS Foundation Trust guidelines and with patient consent, 11 patients with chronic wounds of various aetiologies and wound durations were enrolled in a multicentre, clinical 4-week evaluation.

RESULTS

Over a 4-week evaluation period, all patients showed a significant improvement in wound healing parameters including average tissue type, condition of periwound skin, patient comfort, exudate levels. The assessments demonstrated a significant decrease in necrotic and sloughy tissue (from >75% at the start of treatment), replaced with healthy granulation and epithelial tissue (>80% by week 4). Significant reduction in pain score was also reported in all patients, with average pain score at the start of the evaluation reducing from 5.8 ± 2.7 to a score of 2.5 ± 1.9 within 3 weeks.

CONCLUSION

The complicated wounds seen in this study were previously non-healing and MaxioCel, with BMG technology, demonstrated both significant clinical improvement and a positive impact on patient quality of life within just 4 weeks, resulting in its addition to the team's woundcare formulary.

Preparation of highly stable and ultrasmooth chemically grafted thin films of chitosan

Chitosan-coated surfaces are of great interest for biomedical applications (antibacterial coatings, implants, would healing, single-cell microfluidics…). However, one major limitation of chitosan-based systems is the high solubility of the polymer under acidic aqueous conditions. Herein, we describe a simple procedure to prepare extremely smooth and stable chitosan coatings. In detail, chitosan films with a low degree of N-acetylation and of thicknesses varying from 40 nm to 10 μm were grafted onto epoxy-functionalized silicon wafers via an optimized water-temperature treatment (WTT). The formation of a grafted chitosan network insoluble in acidic aqueous media (pH 3.5) was evidenced and the films were stable for at least 2 days at pH 3.5. The film morphology and the swelling behavior were characterized by atomic force microscopy (AFM) and neutron reflectivity, which showed that the film roughness was extremely low. The physical cross-linking of the films was demonstrated using infrared spectroscopy, dynamic mechanical analysis (DMA) and wide-angle X-ray scattering (WAXS). Finally, we show that the swelling behavior of such films was largely influenced by the environmental conditions, such as the pH or ionic strength of the solution.

Quaternized chitosan/chitosan nanofibrous mats: An approach toward bioactive materials for tissue engineering and regenerative medicine

Chitosan based nanofibers are emerging biomaterials with a plethora of applications, especially in medicine and healthcare. Herein, binary quaternized chitosan/chitosan fibers are reported for the first time. Their preparation strategy consisted in the electrospinning of ternary chitosan/quaternized chitosan/poly(ethylene oxide) solutions followed by the selective removal of poly(ethylene oxide). Their morphology and performances were systematically investigated and discussed in detail. It was found that the fibers had reversible water vapor adsorption/desorption and showed swelling degrees similar to commercial wound dressings. They presented good mechanical properties and the content of quaternized chitosan modulated their bioadhesion, mucoadhesion and biodegradation rate and conferred them strong antimicrobial activity. Tests on normal human fibroblasts confirmed their safely use in contact with tissues and the biocompatibility investigation on rats showed no harmful effect when subcutaneous implanted. All these proved the binary quaternized chitosan/chitosan fibers as bioactive materials suitable for tissue regeneration, wound healing and drug delivery systems.

Potential Oral Anticancer Therapeutic Agents of Hexahydrocurcumin-Encapsulated Chitosan Nanoparticles against MDA-MB-231 Breast Cancer Cells

Hexahydrocurcumin-encapsulated chitosan nanoparticles (HHC-CS-NPs) were formulated by oil-in-water emulsification and ionotropic gelation and optimized using the Box-Behnken design. The particle size, zeta potential, and encapsulation efficiency of the optimized HHC-CS-NPs were 256 ± 14 nm, 27.3 ± 0.7 mV, and 90.6 ± 1.7%, respectively. The TEM analysis showed a spherical shape and a dense structure with a narrow size distribution. The FT-IR analysis indicated no chemical interaction between the excipients and the drugs in the nanoparticles, but the existence of the drugs was molecularly dispersed in the nanoparticle matrices. The drug release profile showed a preliminary burst release followed by a sustained release under simulated gastrointestinal (GI) and physiological conditions. A stability study suggested that the HHC-CS-NPs were stable under UV light, simulated GI, and body fluids. The in vitro bioaccessibility and bioavailability of the HHC-CS-NPs were 2.2 and 6.1 times higher than those of the HHC solution, respectively. The in vitro evaluation of the antioxidant, anti-inflammatory, and cytotoxic effects of the optimized HHC-CS-NPs demonstrated that the CS-NPs significantly improved the biological activities of HHC in radical scavenging, hemolysis protection activity, anti-protein denaturation, and cytotoxicity against MDA-MB-231 breast cancer cells. Western blot analysis showed that the apoptotic protein expression of Bax, cytochrome C, caspase-3, and caspase-9, were significantly up-regulated, whereas the anti-apoptotic protein Bcl-2 expression was down-regulated in the HHC-CS-NP-treated cells. Our findings suggest that the optimized HHC-CS-NPs can be further developed as an efficient oral treatment for breast cancer.

Preparation and Performance of Biodegradable Poly(butylene adipate-co-terephthalate) Composites Reinforced with Novel AgSnO2 Microparticles for Application in Food Packaging

Biodegradable composites with antimicrobial properties were prepared with microparticles of silver stannate (AgSnO₂) and poly(butylene adipate-co-terephthalate) (PBAT) and tested for applications in food packaging. The PBAT matrix was synthesized and confirmed by ¹H-nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, and X-ray diffraction (XRD). Ultrasonic and coprecipitation methods were used to synthesize AgSnO₂. A two-step mixing method and a solvent cast technique were utilized to fabricate the PBAT composites (different weight % of AgSnO₂) for packaging foods. Attenuated total reflection-infrared spectroscopy, X-ray photoelectron spectroscopy, XRD, and scanning electron microscopy were used to investigate the formation, structure, and size of the composites. Thermogravimetric analysis and differential thermal calorimetry were used to examine the PBAT/AgSnO₂ composites. The best characteristics are exhibited in 5.0 wt. % AgSnO₂ loaded PBAT composite. The tensile strength, elongation at break, water vapor transmission rate, and oxygen transmission rate were 22.82 MPa, 237.00%, 125.20 g/m²/day, and 1104.62 cc/m²/day.atm, respectively. Incorporating AgSnO₂ enhanced the hydrophobicity of the PBAT materials as evaluated by the water contact angle. The 5.0 wt. % AgSnO₂/PBAT film shows a favorable zone of inhibition against the bacteria pathogens S. aureus and E. coli, according to an evaluation of its antimicrobial activity. The weight loss of 5% AgSnO₂/PBAT film was 78.4% after eight weeks in the natural soil environments. In addition, the results of food quality studies recommend that AgSnO₂/PBAT (5.0 wt. %) film had a longer food shelf life than the neat PBAT and commercial, increasing it from one to 14 days for carrot vegetables.

Deep Chemical and Physico-Chemical Characterization of Antifungal Industrial Chitosans-Biocontrol Applications

Five different chitosan samples (CHI-1 to CHI-5) from crustacean shells with high deacetylation degrees (>93%) have been deeply characterized from a chemical and physicochemical point of view in order to better understand the impact of some parameters on the bioactivity against two pathogens frequently encountered in vineyards, Plasmopara viticola and Botrytis cinerea. All the samples were analyzed by SEC-MALS, ¹H-NMR, elemental analysis, XPS, FTIR, mass spectrometry, pyrolysis, and TGA and their antioxidant activities were measured (DPPH method). Molecular weights were in the order: CHI-4 and CHI-5 (MW >50 kDa) > CHI-3 > CHI-2 and CHI-1 (MW < 20 kDa). CHI-1, CHI-2 and CHI-3 are under their hydrochloride form, CHI-4 and CHI-5 are under their NH₂ form, and CHI-3 contains a high amount of a chitosan calcium complex. CHI-2 and CHI-3 showed higher scavenging activity than others. The bioactivity against B. cinerea was molecular weight dependent with an IC50 for CHI-1 = CHI-2 (13 mg/L) ≤ CHI-3 (17 mg/L) < CHI-4 (75 mg/L) < CHI-5 (152 mg/L). The bioactivity on P. viticola zoospores was important, even at a very low concentration for all chitosans (no moving spores between 1 and 0.01 g/L). These results show that even at low concentrations and under hydrochloride form, chitosan could be a good alternative to pesticides.

The effect of essential oils mixture on chitosan-based film surface energy and antiadhesion activity against foodborne bacteria

In the food sector, the formation of biofilms as a result of microbial adherence on food-grade surfaces causes a major problem resulting in significant economic losses. Thereby, this work aimed to elaborate a biodegradable film using chitosan (CS-film) and reinforce its antiadhesion activity by incorporating pelargonium, clove, thyme, and cinnamon essential oils (EOs). Firstly, the antibacterial activity of these EOs alone and combined against four foodborne bacteria were analyzed by the microdilution method. Synergism was observed in the case of EOs combination. Secondly, the physicochemical characteristics and antiadhesion behavior of the CS-films were assessed by the contact angle method and ESEM, respectively. Results revealed that the EOs mixture treatment impacted considerably the physicochemical characteristics of the CS-film and reduced its qualitative and quantitative hydrophobicity. Moreover, the treated CS-film showed a strong antiadhesion behavior against Enterococcus hirae, Pseudomonas aeruginosa, Escherichia coli, and Staphylococcus aureus with percentages of non-covered surface equal to 97.65 ± 1.43%, 98.76 ± 0.32%, 99.68 ± 0.28%, and 95.63 ± 1.32% respectively. From all these results, the CS-film treated with the mixture of EOs presents a great potential for application as surface coating and food packaging preventing microbial adhesion and thus, avoiding food contamination and spoilage.

Chitosan Edible Films and Coatings with Added Bioactive Compounds: Antibacterial and Antioxidant Properties and Their Application to Food Products: A Review

Chitosan is the deacetylated form of chitin regarded as one of the most abundant polymers and due to its properties, both chitosan alone or in combination with bioactive substances for the production of biodegradable films and coatings is gaining attention in terms of applications in the food industry. To enhance the antimicrobial and antioxidant properties of chitosan, a vast variety of plant extracts have been incorporated to meet consumer demands for more environmentally friendly and synthetic preservative-free foods. This review provides knowledge about the antioxidant and antibacterial properties of chitosan films and coatings enriched with natural extracts as well as their applications in various food products and the effects they had on them. In a nutshell, it has been demonstrated that chitosan can act as a coating or packaging material with excellent antimicrobial and antioxidant properties in addition to its biodegradability, biocompatibility, and non-toxicity. However, further research should be carried out to widen the applications of bioactive chitosan coatings to more foods and industries as well was their industrial scale-up, thus helping to minimize the use of plastic materials.

Long-Term Refrigerated Storage of Beef Using an Active Edible Film Reinforced with Mesoporous Silica Nanoparticles Containing Oregano Essential Oil (Lippia graveolens Kunth)

Beef is a fundamental part of the human diet, but it is highly susceptible to microbiological and physicochemical deterioration which decrease its shelf life. This work aimed to formulate an active edible film (AEF) incorporated with amino-functionalized mesoporous silica nanoparticles (A-MSN) loaded with Mexican oregano (Lippia graveolens Kunth) essential oil (OEO) and to evaluate its effect as a coating on fresh beef quality during refrigerated storage. The AEF was based on amaranth protein isolate (API) and chitosan (CH) (4:1, w/w), to which OEO emulsified or encapsulated in A-MSN was added. The tensile strength (36.91 ± 1.37 MPa), Young's modulus (1354.80 ± 64.6 MPa), and elongation (4.71%) parameters of AEF made it comparable with synthetic films. The antimicrobial activity of AEF against E. coli O157:H7 was improved by adding 9% (w/w) encapsulated OEO, and interactions of glycerol and A-MSN with the polymeric matrix were observed by FT-IR spectroscopy. In fresh beef, after 42 days, AEF reduced the population growth (Log CFU/cm², relative to uncoated fresh beef) of Brochothrix thermosphacta (5.5), Escherichia coli (3.5), Pseudomonas spp. (2.8), and aerobic mesophilic bacteria (6.8). After 21 days, odor acceptability of coated fresh beef was improved, thus, enlarging the shelf life of the beef and demonstrating the preservation capacity of this film.

Synthesis and Evaluation of Poly(3-hydroxypropyl Ethylene-imine) and Its Blends with Chitosan Forming Novel Elastic Films for Delivery of Haloperidol

This study aimed to develop novel elastic films based on chitosan and poly(3-hydroxypropyl ethyleneimine) or P3HPEI for the rapid delivery of haloperidol. P3HPEI was synthesized using a nucleophilic substitution reaction of linear polyethyleneimine (L-PEI) with 3-bromo-1-propanol. ¹H-NMR and FTIR spectroscopies confirmed the successful conversion of L-PEI to P3HPEI, and the physicochemical properties and cytotoxicity of P3HPEI were investigated. P3HPEI had good solubility in water and was significantly less toxic than the parent L-PEI. It had a low glass transition temperature (T_g = -38.6 °C). Consequently, this new polymer was blended with chitosan to improve mechanical properties, and these materials were used for the rapid delivery of haloperidol. Films were prepared by casting from aqueous solutions and then evaporating the solvent. The miscibility of polymers, mechanical properties of blend films, and drug release profiles from these formulations were investigated. The blends of chitosan and P3HPEI were miscible in the solid state and the inclusion of P3HPEI improved the mechanical properties of the films, producing more elastic materials. A 35:65 (%w/w) blend of chitosan-P3HPEI provided the optimum glass transition temperature for transmucosal drug delivery and so was selected for further investigation with haloperidol, which was chosen as a model hydrophobic drug. Microscopic and X-ray diffractogram (XRD) data indicated that the solubility of the drug in the films was ~1.5%. The inclusion of the hydrophilic polymer P3HPEI allowed rapid drug release within ~30 min, after which films disintegrated, demonstrating that the formulations are suitable for application to mucosal surfaces, such as in buccal drug delivery. Higher release with increasing drug loading allows flexible dosing. Blending P3HPEI with chitosan thus allows the selection of desirable physicochemical and mechanical properties of the films for delivery of haloperidol as a poorly water-soluble drug.

Dicalcium Phosphate Dihydrate Mineral Loaded Freeze-Dried Scaffolds for Potential Synthetic Bone Applications

Dicalcium Phosphate Dihydrate (DCPD) mineral scaffolds alone do not possess the mechanical flexibility, ease of physicochemical properties' tuneability or suitable porosity required for regenerative bone scaffolds. Herein, we fabricated highly porous freeze-dried chitosan scaffolds embedded with different concentrations of Dicalcium Phosphate Dihydrate (DCPD) minerals, i.e., 0, 20, 30, 40 and 50 (wt)%. Increasing DCPD mineral concentration led to increased scaffold crystallinity, where the % crystallinity for CH, 20, 30, 40, and 50-DCPD scaffolds was determined to be 0.1, 20.6, 29.4, 38.8 and 69.9%, respectively. Reduction in scaffold pore size distributions was observed with increasing DCPD concentrations of 0 to 40 (wt)%; coalescence and close-ended pore formation were observed for 50-DCPD scaffolds. 50-DCPD scaffolds presented five times greater mechanical strength than the DCPD mineral-free scaffolds (CH). DCPD mineral enhanced cell proliferation for the 20, 30 and 40-DCPD scaffolds. 50-DCPD scaffolds presented reduced pore interconnectivity due to the coalescence of many pores in addition to the creation of closed-ended pores, which were found to hinder osteoblast cell proliferation.

Characterization and release kinetics model of thymol from starch-based nanocomposite film into food simulator

To improve the performance of potato starch films and solve the problems of high volatility and low stability of thymol (Thy), thymol was loaded into the channel of SBA-15 to prepare Thy-SBA-15, and the Thy-SBA-15/potato starch film was prepared. The results showed thymol was successfully loaded into the pores of SBA-15. The addition of Thy-SBA-15 enhanced the tensile strength of potato starch film (3.93 Mpa), reduced the water vapor permeability (1.56 × 10^-12  g·d^-1  m^-1  Pa^-1 , WVP) and moisture absorption (80.97%, MA), which enhanced the barrier properties of the films. Thy-SBA-15 had good compatibility with potato starch films. Notably, the thymol released from Thy-SBA-15/potato starch film was initially explosive, and then continuous, which showed this film could effectively slow down the release rate of thymol and prolong the fresh-keeping period of food. The Korsmeyer-Peppas model M t M ∞ = k t n $$ \left(\frac{{\mathrm{M}}_{\mathrm{t}}}{{\mathrm{M}}_{\infty }}=\mathrm{k}{\mathrm{t}}^{\mathrm{n}}\right) $$ (R²  > .96) had the best fit for the release curve of thymol. PRACTICAL APPLICATIONS: This work offers a new method for the preparation of potato starch sustained-release antibacterial film, and provides a theoretical basis and technical support for the development of intelligent packaging.

Self-Healing Chitosan Hydrogels: Preparation and Rheological Characterization

The paper aims at the preparation of chitosan self-healing hydrogels, designed as carriers for local drug delivery by parenteral administration. To this aim, 30 hydrogels were prepared using chitosan and pyridoxal 5-phosphate (P5P), the active form of vitamin B6 as precursors, by varying the ratio of glucosamine units and aldehyde on the one hand and the water content on the other hand. The driving forces of hydrogelation were investigated by nuclear magnetic resonance (NMR), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction, and polarized light microscopy (POM) measurements. NMR technique was also used to investigate the stability of hydrogels over time, and their morphological particularities were assessed by scanning electron microscopy (SEM). Degradability of the hydrogels was studied in media of four different pH, and preliminary self-healing ability was visually established by injection through a syringe needle. In-depth rheological investigation was conducted in order to monitor the storage and loss moduli, linear viscoelastic regime, and structural recovery capacity. It was concluded that chitosan crosslinking with pyridoxal 5-phosphate is a suitable route to reach self-healing hydrogels with a good balance of mechanical properties/structural recovery, good stability over time, and degradability controlled by pH.