Synthesis, characterization and antibacterial activity of salicyloyl chitosan

Salicyloyl chitosan (SCS) with different degrees of substitution (DS) and molecular weight (MW) were synthesized from chitosan and salicylic acid. Their structures were characterized by UV, FTIR, 1H NMR and XRD, which showed that the acylate reaction took place at the N-position of chitosan. The DS value of SCS ranged from 0.10 to 0.71. The antibacterial activities were assessed according to an inhibition zone method against Escherichia coli and Staphylococcus aureus. The antibacterial results indicated that the antibacterial activity of SCS was strengthened than chitosan with the increase of DS for both E. coli and S. aureus. As a SCS solvent, the antibacterial activity of the formic acid was most effective followed by acetic acid and lactic acid. In addition, the SCS with higher MW was more effective in inhibiting bacterial growth.