Preparation, characterization and antimicrobial activity of chitosan–Zn complex

Five chitosan–zinc complexes with different zinc content were prepared and characterized by FT-IR, XRD, AAS and elemental analysis. It was found that the complexes with different zinc content had different molecule structure. Three possible structures corresponding to different chelate ratios were proposed and preliminarily complexation mechanisms were discussed. In vitro antimicrobial activities of complexes were evaluated against 11 species of bacteria and fungi. The complexes showed wide spectrum of effective antimicrobial activities, which were 2–8 times and 4–16 times higher than those of chitosan and zinc sulfate, respectively, and improved with increasing content of zinc ions. The complexes had a better antibacterial activity than antifungal activity, and showed excellent activity particularly against E. Coli. and Corynebacterial both with a MIC value of 0.000313% (CS–Zn w/v).