Biodegradability Study of Modified Chitosan Films with Cinnamic Acid and Ellagic Acid in Soil.

Currently, natural polymer materials with bactericidal properties are extremely popular. Unfortunately, although the biopolymer material itself is biodegradable, its enrichment with bactericidal compounds may affect the efficiency of biodegradation by natural soil microflora. Therefore, the primary objective of this study was to evaluate the utility of fungi belonging to the genus Trichoderma in facilitating the degradation of chitosan film modified with cinnamic acid and ellagic acid in the soil environment. Only two strains (T.07 and T.14) used chitosan films as a source of carbon and nitrogen. However, their respiratory activity decreased with the addition of tested phenolic acids, especially cinnamic acid. Addition of Trichoderma isolates to the soil increased oxygen consumption during the biodegradation process compared with native microorganisms, especially after application of the T.07 and T.14 consortium. Isolates T.07 and T.14 showed high lipolytic (55.78 U/h and 62.21 U/h) and chitinase (43.03 U/h and 41.27 U/h) activities. Chitinase activity after incorporation of the materials into the soil was higher for samples enriched with T.07, T.14 and the consortium. The isolates were classified as Trichoderma sp. and Trichoderma koningii. Considering the outcomes derived from our findings, it is our contention that the application of Trichoderma isolates holds promise for expediting the degradation process of chitosan materials containing bactericidal compounds.

Photochemical stability of chitosan films doped with cannabis oil.

The effect of UV radiation from three different sources on chitosan (CS) films containing the addition of 10% by weight of cannabis oil was investigated. Cannabis oil (CBD) alone exposed to UV is unstable, but its photostability significantly increases in the chitosan matrix. The course of photochemical reactions, studied by FTIR spectroscopy, is slow and inefficient in chitosan with CBD, even under high-energy UV sources. The research also included chitosan films with CBD cross-linked with dialdehyde starch (DAS). Using AFM microscopy and contact angle measurements, the morphology and surface properties of prepared chitosan films with CBD were investigated, respectively. It was found that CBD embedded in CS is characterized by the best photostability under the influence of an LED emitting long-wave radiation. Using a monochromatic and polychromatic UV lamp (HPK and UV-C) emitting high-energy radiation, gradual degradation accompanied by oxidation was observed, both in the CS chains and in the CBD additive. Additionally, changes in surface properties are observed during UV irradiation. It was concluded that CS protects CBD against photodegradation, and a further improvement in photochemical stability is achieved after system cross-linking with DAS.

Chitosan Extracted from the Biomass of Tenebrio molitor Larvae as a Sustainable Packaging Film.

Waste from non-degradable packaging materials poses a serious environmental risk and has led to interest in developing sustainable bio-based packaging materials. Sustainable packaging materials have been made from diverse naturally derived materials such as bamboo, sugarcane, and corn starch. In this study, we made a sustainable packaging film using chitosan extracted from the biomass of yellow mealworm (Tenebrio molitor) shell waste. The extracted chitosan was used to create films, cross-linked with citric acid (CA) and with the addition of glycerol to impart flexibility, using the solvent casting method. The successful cross-linking was evaluated using Fourier-Transform Infrared (FTIR) analysis. The CA cross-linked mealworm chitosan (CAMC) films exhibited improved water resistance with moisture content reduced from 19.9 to 14.5%. Improved barrier properties were also noted, with a 28.7% and 10.2% decrease in vapor permeability and vapor transmission rate, respectively. Bananas were selected for food preservation, and significant changes were observed over a duration of 10 days. Compared to the control sample, bananas packaged in CAMC pouches exhibited a lesser loss in weight because of excellent barrier properties against water vapor. Moreover, the quality and texture of bananas packaged in CAMC pouch remained intact over the duration of the experiment. This indicates that adding citric acid and glycerol to the chitosan structure holds promise for effective food wrapping and contributes to the enhancement of banana shelf life. Through this study, we concluded that chitosan film derived from mealworm biomass has potential as a valuable resource for sustainable packaging solutions, promoting the adoption of environmentally friendly practices in the food industry.

Chitosan membranes incorporating Aloe vera glycolic extract with joint synthesis of silver nanoparticles for the treatment of skin lesions.

New wound dressings based on polymeric membranes have been widely exploited for clinical applications to assist in the healing process and prevent additional complications (e.g., bacterial infections). Here we propose the development of a new production method of polymeric membranes based on chitosan, incorporating glycolic extract of Aloe vera with joint synthesis of silver nanoparticles for use as a new bioactive dressing. The membranes were obtained by casting technique, and their morphological, physicochemical characteristics, degree of swelling, degradation profile and antimicrobial activity evaluated. Morphological analyzes confirmed the synthesis and presence of silver nanoparticles in the polymeric membrane. The chemical compatibility between the materials was demonstrated through thermal analysis (TGA and DSC) combined with ATR-FTIR tests, showing the complexation of the membranes (Mb-Ch-Ex.Av-NPs). All membranes were characterized as hydrophilic material (with a contact angle (Ó©) < 90°); however, the highest degree of swelling was obtained for the chitosan. (Mb-Ch) membrane (69.91 ± 5.75%) and the lowest for Mb-Ch-Ex.Av-NPs (26.62 ± 8.93%). On the other hand, the degradation profile was higher for Mb-Ch-Ex.Av-NPs (77.85 ± 7.51%) and lower for Mb-Ch (57.60 ± 2.29%). The manufactured bioactive dressings showed activity against Escherichia coli and Staphylococcus aureus. Our work confirmed the development of translucent and flexible chitosan-based membranes, incorporating Aloe vera glycolic extract with joint synthesis of silver nanoparticles for use as a new bioactive dressing, with proven antimicrobial activity.

Laccase-Mediated Oxidation of Phenolic Compounds from Wine Lees Extract towards the Synthesis of Polymers with Potential Applications in Food Packaging.

Laccase from Trametes versicolor was applied to produce phenolic polymeric compounds with enhanced properties, using a wine lees extract as the phenolic source. The influence of the incubation time on the progress of the enzymatic oxidation and the yield of the formed polymers was examined. The polymerization process and the properties of the polymeric products were evaluated with a variety of techniques, such as high-pressure liquid chromatography (HPLC) and gel permeation chromatography (GPC), Fourier-transform infrared (FTIR) and nuclear magnetic resonance (NMR) spectroscopies, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The enzymatic polymerization reaction resulted in an 82% reduction in the free phenolic compounds of the extract. The polymeric product recovery (up to 25.7%) and the molecular weight of the polymer depended on the incubation time of the reaction. The produced phenolic polymers exhibited high antioxidant activity, depending on the enzymatic oxidation reaction time, with the phenolic polymer formed after one hour of enzymatic reaction exhibiting the highest antioxidant activity (133.75 and 164.77 µg TE mg-1 polymer) towards the ABTS and DPPH free radicals, respectively. The higher thermal stability of the polymeric products compared to the wine lees phenolic extract was confirmed with TGA and DSC analyses. Finally, the formed phenolic polymeric products were incorporated into chitosan films, providing them with increased antioxidant activity without affecting the films' cohesion.

Colorimetric Glucose Biosensor Based on Chitosan Films and Its Application for Glucose Detection in Beverages Using a Smartphone Application.

Nowadays, biosensors are gaining increasing interest in foods' and beverages' quality control, owing to their economic production, enhanced sensitivity, specificity, and faster analysis. In particular, colorimetric biosensors can be combined with color recognition applications on smartphones for the detection of analytes, rendering the whole procedure more applicable in everyday life. Herein, chitosan (CS) films were prepared with the deep eutectic solvent (DES) choline chloride/urea/glycerol (ChCl:U:Gly). Glucose oxidase (GOx), a widely utilized enzyme in quality control, was immobilized within CS films through glutaraldehyde (GA), leading to the formation of CS/GOx films. The optimized GOx concentration and DES content were determined for the films. Moreover, the effect of the pH and temperature of the glucose oxidation reaction on the enzymatic activity of GOx was studied. The structure, stability, and specificity of the CS/GOx films as well as the Km values of free and immobilized GOx were also determined. Finally, the analytical performance of the films was studied by using both a spectrophotometer and a color recognition application on a smartphone. The results demonstrated that the films were highly accurate, specific to glucose, and stable when stored at 4 °C for 4 weeks and when reused 10 times, without evident activity loss. Furthermore, the films displayed a good linear response range (0.1-0.8 mM) and a good limit of detection (LOD, 33 µM), thus being appropriate for the estimation of glucose concentration in real samples through a smartphone application.

Measurement of the degree of deacetylation in chitosan films by FTIR, 1H NMR and UV spectrophotometry.

The chitosan films were prepared from shrimp, squid, and crab to corroborate that regardless of the source of the chitosan, it was possible to measure the degree of deacetylation. In this work, the degree of deacetylation of chitosan was evaluated via UV, FTIR and 1H NMR spectrophotometry methodologies. Values in a range of 74 to 99% degree of deacetylation (DD) were obtained and varied depending on the method used and the source of chitosan. The spectrophotometric method is one of the most commonly used for this determination; however, it has the limitation that D-glucosamine and N-acetylglucosamine share similar wavelengths. All three methods were simple and provided rapid analysis; however, NMR, in particular, was expensive due to its equipment specifications. For this reason, its important to select the simplest method than can be routinely used.•The simplest used technique to determine the degree of deacetylation is infrared spectroscopy.•The degree of acetylation of chitosan is related to its physicochemical properties; its determination is an important parameter due to its association with chitosan applications in different industrial areas.•The 1H NMR method is very precise and requires expensive equipment and trained personal. Thus, it cannot be used routinely to determine the degree of deacetylation.