Characterization and antimicrobial analysis of chitosan-based films

Synthesis, characterization and application of chitosan-N-(4-hydroxyphenyl)-methacrylamide derivative as a drug and gene carrier

The aim of this study was to develop a green method to fabricate a novel CS modified N-(4-hydroxyphenyl)- methacrylamide conjugate (CSNHMA) and to evaluate its biomedical potential. CSNHMA has been prepared by a simple method via aza Michael addition reaction between CS and N- (4-hydroxyphenyl)-methacrylamide (NHMA) in ethanol. Its structural and morphological properties were characterized by various analysis techniques. The obtained results confirmed that a highly porous network structure of CSNHMA was successfully synthesized via aza Michael addition reaction. Consequently, it was analyzed as a drug and gene carrier. CSNHMA/pGL3 showed an enhanced buffering capacity due to the presence of NHMA moiety leading to higher transfection efficiency in all cancer cells (A549, HeLa and HepG2) as compared to native CS and Lipofectamine®. Therefore, these findings clearly support the possibility of using CSNHMA as a good transfection agent. For in vitro drug release study, we prepared CSNHMA nanoparticles (NPs) and curcumin loaded CSNHMA NPs of size <230 nm respectively via the non-toxic ionic gelation route and the encapsulation efficiency of drug was found to be 77.03%. In vitro drug release studies demonstrated a faster and sustained release of curcumin loaded CSNHMA NPs at pH 5.0 compared to physiological pH.

Development of poly(vinyl alcohol)/starch/ethyl lauroyl arginate blend films with enhanced antimicrobial and physical properties for active packaging

Active packaging films have emerged as alternatives to replace petroleum-based packaging materials. In this work, poly(vinyl alcohol) (PVA)/starch/ethyl lauroyl arginate (LAE) films possessing enhanced properties were prepared. Scanning electron microscopy (SEM) showed that PVA and starch were compatible, the concentrations of LAE greatly affected the structural integrity. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction showed that the inclusion of LAE did not significantly affect the intermolecular interactions and crystal structures of the polymer matrix. With an increase of the LAE content, the tensile strength (TS) was slightly decreased due to the altered microstructures, the elongation at break (EB) significantly increased ascribed to the synergistic effect of acetic acid, glycerol and LAE. The values of TS and EB were 17.25 MPa and 586.08%, respectively when LAE was 10%. Active films showed good barrier properties from UV while retaining the transmittance in the visible light region. The films containing 1% of LAE exhibited antibacterial activity against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), the inhibition zone of bacterial growth gradually expanded with increasing LAE content. This study demonstrates the potential of using LAE as the antibacterial agent for synthesizing natural-based polymeric films for active packaging applications.

Self-Assembly of Soluble Chitosan Derivatives Nanoparticles for Vaccine: Synthesis, Characterization and Evaluation

Herein, a novel chitosan derivative nanoparticle was proposed to function as a delivery carrier. First of all, an improvement was made to the way N-2-hydroxypropyl trimcthyl ammonium chloride chitosan (N-2-HACC) was synthesized. Moreover, the solution to one-step synthesis of N-2-HACC from chitosan (CS) was developed. Different from the previous report, the synthesis process was simplified, and there was a reduction in the amount of 2,3-epoxypropyl trimethyl ammonium chloride (EPTAC) used. With its excellent water solubility maintained, the relatively low degree of substitution was controlled to facilitate the cross-linking reaction. The results obtained from 1H-NMR, FTIR spectroscopy, and XRD indicated a smooth EPTAC onto CS for the formation of N-2-HACC with 59.33% the degree of substitution (DS). According to our results, N-2-HACC could be dissolved in various organic solvents, deionized water, 1% acetic acid aqueous solution, and others at room temperature. Finally, a novel chitosan nanoparticle material was prepared using the self-assembly method with β-glycerophosphate sodium (β-GC), with excellent immune properties achieved, thus providing a new strategy for chitosan self-assembled nanoparticles.

Chitosan crosslinking with pyridoxal 5-phosphate vitamer toward biocompatible hydrogels for in vivo applications

Vitamin B6 is an essential micronutrient in the mammalian diet, with role of coenzyme and synergistic effect with some antibiotics and antitumor drugs. Based on these, we hypothesized that its use for the preparation of hydrogels can yield multifunctional biomaterials suitable for in vivo applications. To this aim, chitosan was reacted with the active form of vitamin B6, pyridoxal 5-phosphate, via acid condensation, when clear hydrogels were obtained. Their investigation by structural characterization methods proved that the hydrogelation was a consequence of both covalent imine formation and physical interactions. The novel hydrogels had microporous morphology and showed shrinking effect in phosphate buffer, indicating good shape preservation and slow dissolution in in vivo environment. Their enzymatic biodegradation could be controlled by the imination degree, varying from 40 to 61% in 21 days. They demonstrated very good in vitro cytocompatibility on normal human dermal fibroblasts cells and no harmful effect on experimental mice, confirming their safely use for in vivo application.

Development of chitosan films incorporated with rambutan (Nephelium lappaceum L.) peel extract and their application in pork preservation

Chitosan (CS) films containing 0, 1, 3 and 5% (w/w) of polyphenol-rich rambutan peel extract (RPE) were developed. The micro-structural characterization and physical and functional properties of the films were determined. Results showed RPE formed strong interactions with CS, making film inner micro-structure become uniform and film crystallinity decline. Amongst different films, CS film containing 5% of RPE showed the lowest light transmission, moisture content (28.35%), water solubility (46.07%), water vapor permeability (8.41 × 10^-10 g m^-1 s^-1 Pa^-1) and oxygen permeability (0.28 cm³ mm m^-2 day^-1 atm^-1). Meanwhile, CS film containing 5% of RPE exhibited the highest tensile strength (38.87 MPa) and elongation at break (51.73%) and the strongest antioxidant and antimicrobial activities. Finally, pork was wrapped with the films and stored at 4 °C for 8 days. Results showed pork wrapped with CS film containing 5% of RPE presented the lowest total volatile basic nitrogen level (9.17 mg/100 g), thiobarbituric acid reactive substance value (0.51 mg malondialdehyde/kg) and total viable count (4.53 log colony forming unit/g) and the best sensory attributes on the eighth day. Our results suggested the potential of CS film containing 5% of RPE as an active packaging material in pork preservation.

Selected Applications of Chitosan Composites

Chitosan is one of the emerging materials for various applications. The most intensive studies have focused on its use as a biomaterial and for biomedical, cosmetic, and packaging systems. The research on biodegradable food packaging systems over conventional non-biodegradable packaging systems has gained much importance in the last decade. The deacetylation of chitin, a polysaccharide mainly obtained from crustaceans and shrimp shells, yields chitosan. The deacetylation process of chitin leads to the generation of primary amino groups. The functional activity of chitosan is generally owed to this amino group, which imparts inherent antioxidant and antimicrobial activity to the chitosan. Further, since chitosan is a naturally derived polymer, it is biodegradable and safe for human consumption. Food-focused researchers are exploiting the properties of chitosan to develop biodegradable food packaging systems. However, the properties of packaging systems using chitosan can be improved by adding different additives or blending chitosan with other polymers. In this review, we report on the different properties of chitosan that make it suitable for food packaging applications, various methods to develop chitosan-based packaging films, and finally, the applications of chitosan in developing multifunctional food packaging materials. Here we present a short overview of the chitosan-based nanocomposites, beginning with principal properties, selected preparation techniques, and finally, selected current research.

Antimicrobial Activities of Chitosan Derivatives

Considering the challenge created by the development of bacterial and fungal strains resistant to multiple therapeutic variants, new molecules and materials with specific properties against these microorganisms can be synthesized, like those synthesized from biopolymers such as chitosan with improved antimicrobial activities. Antimicrobial activities of seven obtained materials were tested on four reference strains belonging to American Type Culture Collection. The best antimicrobial activity was obtained by functionalization by impregnation of chitosan with quaternary ammonium salts, followed by that obtained by functionalization of chitosan with phosphonium. The lowest antibacterial and antifungal effects were expressed by Ch-THIO and Ch-MBT, but new materials obtained with these extractants may be precursors with a significant role in the direct control of active molecules, such as cell growth factors or cell signaling molecules.

Synthesis of New Chitosan from an Endemic Chilean Crayfish Exoskeleton (Parastacus Pugnax): Physicochemical and Biological Properties

Chitin is one of the most abundant natural polysaccharides in the world and it is mainly used to produce chitosan by a deacetylation process. In the present study, the extraction of chitin and chitosan from the Parastacus pugnax (P. pugnax) crayfish exoskeleton was studied for the first time. Thus, the P. pugnax crayfish exoskeleton was converted to chitosan following the steps of depigmentation, deproteinization, and deacetylation. The produced chitosan (Chitosan-CGNA) was characterized in terms of the protein content, solubility, degree of deacetylation, viscosity, molecular weight, FTIR, SEM, XRD, antimicrobial, and antioxidant activity. The results showed that the obtained chitosan had a high degree of deacetylation (91.55%) and a medium molecular weight (589.43 kDa). The antibacterial activity of the chitosan was tested against bacterial strains relevant for the food industry and the lowest minimum inhibitory concentration (MIC) values were evidenced with Salmonella tiphymurium (S. typhimurium), Staphylococcus aureus (S. aureus), Enterococcus faecalis (E. faecalis) and Listeria. Monocytogenes (L. monocytogenes). Moreover, the Chitosan-CGNA showed an effect on DPPH radical scavenging activity, and its antioxidant activity was dependent on concentration and deacetylation degree. These results suggest that P. pugnax exoskeleton could be an excellent natural source for the production of chitosan with potential applications in the health system, and to prevent infections associated with pathogens strains.

Effect of glucose substitution by low-molecular weight chitosan-derivatives on functional, structural and antioxidant properties of maillard reaction-crosslinked chitosan-based films

In this study, the effects of different temperatures, incubation times and types of reducing sugars, including glucose and different low molecular weight (Mw) chito-oligosaccharides (COS) with varying acetylation degree (AD), on the extent of Maillard reaction (MR) on chitosan-based films were studied. Interestingly, an improvement of structural and functional properties of all MR-crosslinked films was noted, which is more pronounced by heating at higher temperature and exposure time. These findings were proved through Fourier-transform infrared and X-ray diffraction analyses. In addition, color change and Ultraviolet spectra demonstrate that glucose addition provides the high extent of MR, followed by COS1 (Mw < 4.4 kDa; AD, 18.20%) and COS2 (Mw < 4.4 kDa; AD, 10.63%). These results were confirmed by enhanced water resistance and thermal properties. Moreover, MR-chitosan/COS films showed the highest mechanical properties, whereas, glucose-loaded films were brittle, as demonstrated by scanning electron microscopy micrographs. Furthermore, MR-chitosan/COS1 films exhibited the better antioxidant behavior followed by chitosan/glucose and chitosan/COS2 films, mainly at higher heating-conditions. Thereby, MR-crosslinked chitosan/COS based films were attractive to be applied as functional and active coating-materials in various fields.

Antimicrobial Food Packaging with Biodegradable Polymers and Bacteriocins

Innovations in food and drink packaging result mainly from the needs and requirements of consumers, which are influenced by changing global trends. Antimicrobial and active packaging are at the forefront of current research and development for food packaging. One of the few natural polymers on the market with antimicrobial properties is biodegradable and biocompatible chitosan. It is formed as a result of chitin deacetylation. Due to these properties, the production of chitosan alone or a composite film based on chitosan is of great interest to scientists and industrialists from various fields. Chitosan films have the potential to be used as a packaging material to maintain the quality and microbiological safety of food. In addition, chitosan is widely used in antimicrobial films against a wide range of pathogenic and food spoilage microbes. Polylactic acid (PLA) is considered one of the most promising and environmentally friendly polymers due to its physical and chemical properties, including renewable, biodegradability, biocompatibility, and is considered safe (GRAS). There is great interest among scientists in the study of PLA as an alternative food packaging film with improved properties to increase its usability for food packaging applications. The aim of this review article is to draw attention to the existing possibilities of using various components in combination with chitosan, PLA, or bacteriocins to improve the properties of packaging in new food packaging technologies. Consequently, they can be a promising solution to improve the quality, delay the spoilage of packaged food, as well as increase the safety and shelf life of food.

Evaluation of bioactive release kinetics from crosslinked chitosan films with Aloe vera

Thermocompression was employed to prepare citric acid-crosslinked chitosan films with Aloe vera (AV) as bioactive compound. Films were easy to handle and mechanical properties did not change with the addition of AV up to 10 wt%, although both TS and EAB decreased for the films with 15 wt% AV, indicating that high AV contents would hinder intermolecular interactions among the formulation components. Maillard reaction occurred between chitosan and citric acid at the processing temperature used (115 °C), while physical interactions took place with AV, as shown by FTIR analysis. All films were insoluble but displayed hydration and limited swelling due to both physical and chemical interactions promoted by AV and citric acid, respectively. A slow AV release, governed by a Fickian diffusion controlled mechanism, and an increase of surface hydrophilicity, which favors cell adhesion, were observed.

Synthesis of chitosan grafted polymethyl methacrylate nanopolymers and its effect on polyvinyl chloride membrane for acetone recovery by pervaporation

In comparison to conventional nanoparticles biopolymer like chitosan based nanoparticles will be of much lower cost, non-toxic and more compatible with polymer membranes. As a cationic polymer surfactant chitosan is able to generate polymer nanoparticles during emulsion polymerization of methyl methacrylate. Accordingly, the organophilicity of polyvinyl chloride (PVC) membrane was significantly improved by incorporating chitosan grafted polymethyl methacrylate (PMMA) nanopolymers(NPs) prepared by emulsion polymerization. The NPs and the PVC-NP blend membranes were characterized. The chitosan: MMA wt. ratio and the wt.% of NP in PVC were optimized by a 5-level factorial design. The membranes prepared from i) PVC, PVC blended with 6.5 wt.% each of ii) chitosan, iii) PMMA and iv) NP showed a pervaporative flux (kg/m²h)/acetone selectivity of 0.439/24.31, 0.477/21.56, 0.461/23.41 and 0.502/27.96, respectively for 5.6 wt.% acetone in feed. The sorption and pervaporation data showed close fitting to ENSIC and six-parameter solution-diffusion model, respectively.

Chitosan derivatives-based films as pH-sensitive drug delivery systems with enhanced antioxidant and antibacterial properties

The purpose of this study was to develop and characterize chitosan (Ch)-based films incorporated with varying molecular weight (Mw) and acetylation degree (AD) chitosan-depolymerization-products (CDP), to be applied as drug delivery materials. As compared to Ch-film, optical and antioxidant potentials of Ch/CDP-based films were improved, particularly using low Mw and AD-CDP. Whereas, films water resistance, mechanical and antibacterial properties increased as CDP-Mw increased and AD decreased. For the thermal and swelling behaviors, better values were obtained using higher Mw and AD-CDP. Further, to assess their in vitro ciprofloxacin (CFX)-release behavior, loaded-CFX Ch/CDP-based films, crosslinked using glutaraldehyde, were prepared. Expect of elongation at break, crosslinked CFX-loaded films showed increased optical, water resistance, tensile strength and thermal properties, as compared to unloaded films. The CFX-release profiles indicated that a slower and sustained release was observed, particularly when using lower Mw and AD-CDP, and mainly for the crosslinked films during 48 h. These films can release CFX for up to 54% in 6 and 24 h, at pH 1.2 and 7.4, respectively. Through this study, novel biodegradable, swellable and pH-sensitive crosslinked Ch/CDP-based films may be considered as suitable and promising drug delivery systems.

Characterization and antibacterial properties of epsilon-poly- l-lysine grafted multi-functional cellulose beads

In recent years, harmful microorganisms in water pose great harm to ecological environment and human health. To solve this problem, epsilon-poly-l-lysine (EPL) grafted cellulose beads were prepared via 2, 2, 6, 6-tetramethylpiperidine-1-oxyl (TEMPO) mediated oxidation and carbodiimide mediated cross-linking reaction. Hydroxyl groups on C6 of cellulose were oxidized to carboxyl groups by TEMPO and grafting reaction was achieved between newly formed carboxyl groups of cellulose and amino of EPL. The beads were characterized by FTIR, SEM, XRD and TGA. The crystalline form of cellulose transformed from cellulose I to cellulose II after being dissolved and regenerated. The grafted cellulose beads showed good antibacterial activities against Gram-negative Escherichia coli, Gram-positive Staphylococcus aureus and Alicyclobacillus acidoterrestris with 10 h. The beads could be biodegraded in soil after 28 days. It is expected that the bio-based composite beads could have potential applications in water purification and food treatment fields.

Use of gamma irradiation technology for modification of bacterial cellulose nanocrystals/chitosan nanocomposite film

The objective of this work was to investigate the influence of different gamma ray dosages (5, 10, and 10 kGy) on the structural, mechanical, surface and barrier properties of chitosan (Ch) based nanocomposite film. The results showed gamma irradiation caused an increase in the surface hydrophobicity, water vapor permeability and sensitivity of films to water and also, yellowness and opacity of films increased, simultaneously. By increasing the irradiation doses up to 10 kGy, the mechanical properties of Ch/BCNC film was significantly enhanced. As observed by FTIR spectra, no change occurred in the chemical functional groups of the films during irradiation. XRD studies confirmed that crystallinity of films was increased after irradiation. The nanocomposite film irradiated by 10 kGy had the highest thermal stability. In conclusion, gamma radiation can be considered as a safe method for sterilization of foods and modification of Ch/BCNC film properties.

Surface coating of chitosan of different degree of acetylation on non surface sized writing and printing grade paper

Chitosan is a renewable biopolymer which can be applied on the surface of writing and printing (W&P) grade paper to enhance its different properties. A variety of chitosan is available based on degree of acetylation (DA), molecular weight, viscosity, etc. DA has a profound effect on the performance of chitosan in many applications. Present study compared the performance of different DA chitosan for surface application of W&P grade paper. Chitosan samples of 23 %, 16 % and 6% DA were studied for their impact on various physical and surface properties of W&P grade paper. Surface coating of chitosan was done at 1.6 ± 0.2 g/m² (lower dose) and 2.3 ± 0.3 g/m² (higher dose) on W&P grade paper. Some properties including air permeance, TEA, showed considerable effect of DA in which high DA chitosan outperformed the low DA. Broadly, chitosan with different DA had varied impact on individual properties of paper.

Development of Chitosan/Peptide Films: Physical, Antibacterial and Antioxidant Properties

Chitosan/peptide films were prepared by incorporating peptides (0.4%, w/v) from soy, corn and caseins into chitosan films. The presence of peptides significantly affected the physical, antibacterial and antioxidative properties of chitosan films. Among these films, those containing corn peptide showed the best water vapor barrier properties, and the tensile strength and elongation at break increased to 24.80 Mpa and 23.94%, respectively. Characterization of surface hydrophobicity and thermal stability suggested the strongest intermolecular interactions between corn peptides and chitosan. Moreover, films containing casein peptides showed the highest antibacterial activity and radical scavenging activity. The DPPH scavenging rate of films containing casein peptides reached 46.11%, and ABTS scavenging rate reached 66.79%. These results indicate the chitosan/peptide films may be promising food packaging materials.

Supramolecular aggregates of cyclodextrins with co-solvent modulate drug dispersion and release behavior of poorly soluble corticosteroid from chitosan membranes

In this study, the ability of different beta-cyclodextrins to facilitate homogeneous dispersion of triamcinolone acetonide (TA) into chitosan membranes is assessed. Drug loading was assessed through atomic force microscopy (AFM), scanning electron microscopy (MEV-FEG), and X-ray diffraction analyses. Drug interactions with the co-polymer were investigated with Fourier transform infrared spectroscopy, thermal analyses. Swelling assay, and in vitro drug release experiment were used to assess TA release behavior. Undispersed particles of drug were observed to remain in the simple chitosan membranes. Hydroxypropyl-β-cyclodextrin enabled the dispersion of TA into chitosan membranes and subsequent sustained drug release. In addition, the membrane performance as a drug delivery device is improved by adding specified amounts of the co-solvent triethanolamine. The experimental data presented in this study confirm the utility of our novel and alternative approach for obtaining a promising device for slow and controlled release of glucocorticoids, such as triamcinolone acetonide, for topical ulcerations.

Amphiphilic diethylaminoethyl chitosan of high molecular weight as an edible film

Edible films and coatings can enhance the quality of food products, protecting them from biological deterioration, especially against fungal diseases and pathogenic microorganisms. In this study, films from chitosan, diethylaminoethyl-chitosan (DEAE-CH) and its hydrophobicized derivative DEAE-CH-DD were prepared by casting and their physicochemical and antimicrobial properties evaluated. The grafting with DEAE and dodecyl groups resulted in films with an elasticity modulus up to five times higher than commercial chitosan and increased water vapor permeability. Field emission gun - scanning electron microscopy and atomic force microscopy techniques showed films with smooth surfaces and the contact angle measurements revealed a correlation between the grafted group and hydrophilic/hydrophobic nature of the surface of the film. The amphiphilic derivatives exhibited better antimicrobial activity than unmodified chitosan against Penecillium expansum, Alternaria alternata and Alternaria solani. The amphiphilics DEAE-CH and DEAE-CH-DD showed no toxicity and delayed rotting and loss of water in strawberries and bananas, suggesting that this kind of film has great potential for increasing the shelf-life of different fruits.

Phenothiazine-chitosan based eco-adsorbents: A special design for mercury removal and fast naked eye detection

The aim of the paper was to investigate the ability of an eco-friendly luminescent xerogel prepared by chitosan crosslinking with a phenothiazine luminogen to detect and remove heavy metals. Its ability to give a divergent morphological and optical response towards fifteen environmental relevant metals was investigated by naked eye and UV lamp, fluorescence spectroscopy and scanning electron microscopy. A distinct response was noted for mercury, consisting in the transformation of the xerogel into a rubber-like material accompanied by the red shifting of the color of emitted light from yellow-green to greenish-yellow domain. The particularities of the metals anchoring into the xerogel were analyzed by FTIR spectroscopy and X-ray diffraction. The morphological changes and the metal uptake were analyzed by SEM-EDAX, swelling and gravimetric methods. It was concluded that mercury has a superior affinity towards this heteroatoms rich system, leading to a secondary crosslinking. This directed a great absorption capacity of 1673 mg/g and a specific morphological response for mercury ion concentrations up to 0.001 ppm.

Citryl-imine-PEG-ylated chitosan hydrogels - Promising materials for drug delivery applications

The present paper focuses on the synthesis and characterization of new hydrogels and drug delivery systems, designed for local therapy. The hydrogels were obtained by reacting PEG-ylated chitosan derivatives with citral in different molar ratios of their functionalities. The drug delivery systems were obtained by the in situ hydrogelation of PEG-ylated chitosan derivatives with citral, in the presence of a hydrophilic anti-inflammatory drug, diclofenac sodium salt. The hydrogels and the drug delivery systems were characterized from the structural, supramolecular and morphological points of view by FTIR spectroscopy, wide angle X-ray diffraction, polarized optical microscopy and scanning electron microscopy. The in vitro release kinetics of the drug has been monitored in physiological conditions, while the in vivo release was evaluated by the somatic pain model on rats. The in vitro enzymatic degradability of the hydrogels was evaluated in the presence of lysozyme, leading to a significant mass loss of 47% in 21 days. All the findings, recommend the investigated materials as promising candidates for local drug delivery applications.

Chitosan Film Containing Mansoa hirsuta Fraction for Wound Healing

Chitosan films entrapped with the Mansoa hirsuta fraction (CMHF) was developed as a new dressing for wound care. The chromatographic profile of the M. hirsuta fraction (MHF) was evaluated by ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry, and the results showed that MHF is rich in acid triterpenes. Physicochemical characterization of the films prepared using the solvent casting method was performed by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetry (TGA), differential scanning calorimetry (DCS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and mechanical properties. CMHF exhibited characteristic bands of both chitosan and MHF, revealing a physical mixture of both. CMHF presented an amorphous nature, thermostability, and dispersion of MHF in the chitosan matrix, resulting in a rough structure. Incorporation of M. hirsuta fraction into chitosan matrix favorably enhanced the mechanical performance and films thickness. The in vivo wound treatment with CMHF for seven days showed a characteristic area of advanced healing, re-epithelization, cell proliferation, and collagen formation. Furthermore, wound closure reached 100% contraction after 10 days of treatment with modulation of interleukins. The incorporation of M. hirsuta fraction into chitosan films was advantageous and showed great potential for stimulating wound repair and regeneration.

Conception of novel blue crab chitosan films crosslinked with different saccharides via the Maillard reaction with improved functional and biological properties

This work aimed to modify blue crab chitosan-based films through the Maillard reaction (MR) as a novel alternative to improve their functional and biological properties. To this end, different saccharides (glucose (aldohexose), fructose (ketohexose), xylose (aldopentose) and arabinose (aldopentose)), at different weight ratios 0.5, 1.0 and 2.0 % (g/100 g polymer), were studied, and films were heated at 90 °C for 24 h. Based on color changes and browning index measurements, the extent of MR was the highest with aldopentoses, whereas hexoses and particularly ketohexoses, exhibited a relative crosslinking rate. These findings were further reflected with an improvement in treated films mechanical properties and thermal degradation temperatures, and advantageously, barrier properties against UV light and water. In addition, the MR-modified Cs-based films antioxidant activity was interestingly enhanced with mainly aldopentoses. Consequently, MR crosslinked chitosan-based films are promising alternative for active and functional packaging able of food oxidation hindering, especially using aldopentoses.

Structure-properties relationship of chitosan/collagen films with potential for biomedical applications

Chitosan/collagen films were developed and characterized in order to assess the suitability of these films for biomedical applications. Hence, physicochemical, thermal, barrier and mechanical properties were analyzed and related to the film structure, which showed the prevalence of the triple helix of native collagen after the addition of chitosan. Furthermore, collagen fiber diameter changed from 3.9 ± 0.6 μm, for collagen films without chitosan, to 1.8 ± 0.5 μm, for collagen films with low molecular weight chitosan. These results suggested interactions between collagen and chitosan molecules, as observed by Fourier transform infrared (FTIR) analysis. Regarding film barrier properties, chitosan/collagen films showed a water vapor transmission rate around 1174 g m^-2 day^-1, suitable for biomedical applications such as wound healing. Additionally, biological tests confirmed that the chitosan/collagen films developed are suitable for biomedical applications.

Preparation and characterization of thermally crosslinked films based on chitosan and poly(2-ethyl-2-oxasoline)

Сrosslinked films based on chitosan (СHI) and poly(2-ethyl-2-oxazoline) (POZ) were prepared by thermal crosslinking. The optimal synthesis conditions and the composition of the film compositions were determined. The highest yield of the gel fraction was observed for CHI:POZ (80:20) films with a crosslinking time of 4 h at a temperature of 100°С. The main physicochemical properties of films based on pure CHI and CHI:POZ have been studied. The film swelling ability was reduced with the increase of poly(2-ethyl-2-oxazolin) content. The formation of crosslinks between N,N’-methylene-bis-acrylamide and functional amine groups of chitosan was proposed based on IR-spectroscopy data.