DEVELOPMENT AND CHARACTERIZATION OF CHITOSAN AND 4-CHLOROBENZALDEHYDE-BASED SCHIFF BASES AND ASSESSMENT OF THE ANTIMICROBIAL PERFORMANCE OF DERIVED HYDROGELS

Abstract

Introduction. Microbial resistance to antibiotics is a major global health challenge, as the growing number of multidrug-resistant pathogens limits treatment options and increases morbidity and mortality. This situation necessitates the development of eco-friendly and effective alternatives, including novel antibacterial agents. Schiff bases—organic compounds with an imine group (>C=N–)—are promising due to their simple synthesis, structural diversity, and broad biological activities, including antimicrobial effects. Of particular interest are Schiff bases derived from chitosan, a natural polymer known for its biocompatibility, non-toxicity, and high potential for chemical modification, which can improve its physicochemical and biological properties for applications in medicine and biotechnology. This study aimed to synthesise Schiff bases based on chitosan and 4-chlorobenzaldehyde and to evaluate their structural and functional properties. The compounds were characterised by IR and NMR spectroscopy, and their properties were studied using thermal analysis, rheological measurements, and assessment of adhesive behaviour. Results and Discussion. The formation of Schiff bases was confirmed by IR and NMR spectroscopy. Thermal analysis showed increased glass transition temperature and thermal stability of the samples. Hydrogels prepared from methylcellulose and modified chitosan exhibited thixotropic behaviour and significant antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans. Conclusion. Modified chitosan demonstrated improved properties and strong antimicrobial activity, indicating its potential as a basis for creating new antimicrobial materials for use in medicine, cosmetology, and the food industry.