The first electrochemical N-arylation of chitosan. Antibacterial effect of novel cationic chitosan derivatives

Abstract

In this study, we present the first electrochemical N-arylation of chitosan, which serves as a straightforward and convenient method for chemical modification of chitosan under mild conditions. Importantly, this method avoids any undesirable depolymerization of the polysaccharide backbone. Through this process, we successfully synthesized chitosan derivatives with varying molecular weights: low, medium, and high. These derivatives exhibited different degrees of substitution, with values of approximately 20 %, 30 %, and 65 %, respectively. Our elaborately designed polymers possess excellent water solubility across a broad pH range, ranging from strongly alkaline to strongly acidic. Furthermore, we conducted an investigation into the antimicrobial activity of the synthesized derivatives against two bacterial strains, namely S. aureus and E. coli. We found that the antimicrobial effectiveness of the polymers strongly relies on both the degree of substitution and the molecular weight of the derivatives. Notably, derivatives with a high degree of substitution and low molecular weight exhibited the most potent antimicrobial activity. Additionally, we explored the formation of nanoparticles through ionic gelation using highly active antimicrobial derivatives. These nanoparticles displayed an even greater antibacterial effect, comparable to that of commercially available antibiotics. Overall, our findings highlight the significance of electrochemical N-arylation as a viable approach for modifying chitosan, yielding chitosan derivatives with desirable properties for potential applications in various fields, particularly in antimicrobial and nanomedicine domains.