Double noncovalent network chitosan/hyperbranched polyethylenimine/Fe3+ films with high toughness and good antibacterial activity

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.

Synthesis of novel liquid phase exfoliation of chitosan/Bi2Se3 hybrid nanocomposites for in-vitro wound healing

Numerous studies have recently established the potential of chitosan (Chi) to enhance wound healing. Chi is a carbohydrate biopolymer that is biocompatible, low-cost, toxic-free, and has excellent antibacterial properties. In this study, we synthesized Chi/Bi2Se3 hybrid nanocomposites (NCs) using a liquid exfoliation approach. The physicochemical characterization of the hybrid NCs was investigated using X-ray diffraction, Fourier transforms infrared, Thermogravimetric, Scanning electron microscope, and Transmission electron microscope. The antibacterial ability has been investigated versus two pathogens, S. aureus and E. coli. In comparison to bare materials, the hybrid NCs demonstrated better antibacterial activity against both bacterial strains. As a result, the electrostatic attraction of positively charged Chi can easily attract the negatively charged surface of the bacteria cell membrane and NCs generate reactive oxygen species (ROS). This ROS can attack bacteria's intracellular components and eventually kill bacteria. The biocompatibility of the Chi/Bi2Se3 NCs was evaluated against L929 mice fibroblast cells, and there was no evident cytotoxicity. Furthermore, an in-vitro wound scratch test was carried out on L929 mouse fibroblast cells and the Chi/Bi2Se3 hybrid NCs promote wound healing and cell proliferation. These findings suggest that the Chi/Bi2Se3 hybrid NCs as a promising future material for bacteria-infected in-vivo wound healing.

A soft multifunctional film from chitosan modified with disulfide bond cross-links and prepared by a simple method

Chitosan was modified with thioctic acid and used to prepare soft films. As confirmed by FTIR and XPS measurements, a condensation reaction occurred between the amino groups in the chitosan and the carboxyl groups in the lipoic acid to form amide bonds in the modified chitosan. Films were then prepared by casting at ambient conditions, and the effects of the chemical modification on the physical-mechanical, antibacterial, and thermal properties of the films were investigated. The results showed that the tensile strength, flexibility and recovery performance of the modified films were significantly different from those of the unmodified films. For example, the Young's modulus of a pure chitosan film was 2600 MPa, while the modified films were much more flexible with a Young's modulus as low as 32.5 MPa. Moreover, the modified chitosan films were not dissolved or damaged by common organic solvents or in highly acidic (pH 1) or highly basic (pH 13) conditions. The modified films also showed good antibacterial activity against both E coli and S aureus with inhibition rates of almost 100 %. These desirable properties suggest that the modified chitosan films prepared here have possible application prospects in flexible devices and packaging.

Chitosan Based Biodegradable Composite for Antibacterial Food Packaging Application

A recent focus on the development of biobased polymer packaging films has come about in response to the environmental hazards caused by petroleum-based, nonbiodegradable packaging materials. Among biopolymers, chitosan is one of the most popular due to its biocompatibility, biodegradability, antibacterial properties, and ease of use. Due to its ability to inhibit gram-negative and gram-positive bacteria, yeast, and foodborne filamentous fungi, chitosan is a suitable biopolymer for developing food packaging. However, more than the chitosan is required for active packaging. In this review, we summarize chitosan composites which show active packaging and improves food storage condition and extends its shelf life. Active compounds such as essential oils and phenolic compounds with chitosan are reviewed. Moreover, composites with polysaccharides and various nanoparticles are also summarized. This review provides valuable information for selecting a composite that enhances shelf life and other functional qualities when embedding chitosan. Furthermore, this report will provide directions for the development of novel biodegradable food packaging materials.

One-pot synthesis of iron oxide - Gamma irradiated chitosan modified SBA-15 mesoporous silica for effective methylene blue dye removal

The development of adsorption technology and the processing of radiation have both been influenced by chitosan adsorbent (γ-chitosan), a raw material with unique features. The goal of the current work was to improve the synthesis of Fe-SBA-15 utilizing chitosan that has undergone gamma radiation (Fe-γ-CS-SBA-15) in order to investigate the removal of methylene blue dye in a single hydrothermal procedure. High-resolution transmission electron microscopy (HRTEM), High angle annular dark field scanning transmission electron microscopy (HAADF-STEM), small- and wide-angle X-ray powder diffraction (XRD), Fourier transform-infrared spectroscopy (FT-IR) and Energydispersive X-ray spectroscopy (EDS) were used to characterize γ-CS-SBA-15 that had been exposed to Fe. By using N₂-physisorption (BET, BJH), the structure of Fe-γ-CS-SBA-15 was investigated. The study parameters also included the effect of solution pH, adsorbent dose and contact time on the methylene blue adsorption. The elimination efficiency of the methylene blue dye was compiled using a UV-VIS spectrophotometer. The results of the characterization show that the Fe-γ-CS-SBA-15 has a substantial pore volume of 504 m² g^-1 and a surface area of 0.88 cm³ g^-1. Furthermore, the maximum adsorption capacity (Q_max) of the methylene blue is 176.70 mg/g. The γ-CS can make SBA-15 operate better. It proves that the distribution of Fe and chitosan (the C and N components) in SBA-15 channels is uniform.

Double-Network Chitosan-Based Hydrogels with Improved Mechanical, Conductive, Antimicrobial, and Antibiofouling Properties

In recent years, the antimicrobial activity of chitosan-based hydrogels has been at the forefront of research in wound healing and the prevention of medical device contamination. Anti-infective therapy is a serious challenge given the increasing prevalence of bacterial resistance to antibiotics as well as their ability to form biofilms. Unfortunately, hydrogel resistance and biocompatibility do not always meet the demands of biomedical applications. As a result, the development of double-network hydrogels could be a solution to these issues. This review discusses the most recent techniques for creating double-network chitosan-based hydrogels with improved structural and functional properties. The applications of these hydrogels are also discussed in terms of tissue recovery after injuries, wound infection prevention, and biofouling of medical devices and surfaces for pharmaceutical and medical applications.

Effect of branched polyethyleneimine and citric acid on the structural, physical and antibacterial properties of corn starch/chitosan films

To improve the antibacterial and physical properties of corn starch/chitosan films effectively, starch/chitosan/polyethyleneimine (PEI) blend films crosslinked by citric acid (labeled SCPC) with different contents (2.5 %, 5.0 %, 7.5 % and 10.0 %) were prepared by the solution casting method. The films were characterized in detail. The results showed that the addition of 3.75 % PEI improved the tensile strength and elongation at break of the starch/chitosan film simultaneously, but the thermal stability decreased. After CA was incorporated, the tensile strength and thermal stability of the films were enhanced significantly. FTIR, XRD, and ¹H NMR analyses revealed strong interactions among CA, PEI and starch-chitosan. All films showed smooth and homogenous fragile cross-sections. The water vapor permeability of the film decreased overall after PEI and CA addition. Moisture uptake (MU) accelerated after PEI addition, but the balanced MU was reduced by CA cross-linking. All films showed an inhibitory effect on E. coli and S. aureus, and CA incorporation significantly improved the inhibition ability of the film. The SCPC film with 3.75 % PEI and 5.0 % CA addition has the best comprehensive properties, which endowed its application in the bioactive packaging field.

Multi-crosslinked network chitosan films containing caffeic acid and Fe3+ with high anti-oxidation and anti-UV abilities

In this study, caffeic acid (CA) and Fe³⁺ were added to chitosan solution to prepare chitosan/caffeic acid/Fe³⁺ (CCAF) composite films. CA was used to introduce covalent bonds and hydrogen bonds. Fe³⁺ was used to introduce metal coordination bonds which combined with hydrogen bond and covalent bonds to form a multi-crosslinked system to enhance the tensile strength (TS), improve the antioxidant properties and UV resistance performance. The results showed that the TS of chitosan/caffeic acid (CCA) film with the addition of 0.3 mmol CA was increased by 36.6 % compared with pure chitosan film. The TS of the CCAF film increased from 42.6 MPa to 73.9 MPa with an increase of 73.5 %. The free radical scavenging rate of CCA film and CCAF film, in comparison to pure chitosan film, were improved by 155.7 % and 148.24 %, respectively. The UV resistance property of the CCAF solution was tested at 365 nm and the results showed that the UV barrier rate reached 99.99 %. The water vapor transmission (WVT) and water vapor permeability (WVP) of CCAF film both showed a 25.71 % reduction compared to that of the chitosan film. Besides, the composite film also showed excellent antibacterial properties, which provided the possibility for more applications.

Recent Research on Hybrid Hydrogels for Infection Treatment and Bone Repair

The repair of infected bone defects (IBDs) is still a great challenge in clinic. A successful treatment for IBDs should simultaneously resolve both infection control and bone defect repair. Hydrogels are water-swollen hydrophilic materials that maintain a distinct three-dimensional structure, helping load various antibacterial drugs and biomolecules. Hybrid hydrogels may potentially possess antibacterial ability and osteogenic activity. This review summarizes the recent progress of different kinds of antibacterial agents (including inorganic, organic, and natural) encapsulated in hydrogels. Several representative hydrogels of each category and their antibacterial mechanism and effect on bone repair are presented. Moreover, the advantages and disadvantages of antibacterial agent hybrid hydrogels are discussed. The challenge and future research directions are further prospected.