Synthesis of 2-Hydroxypropyl Dimethylbenzyl Ammonium N,O-Carboxymethyl Chitosan Chloride and Its Antibacterial Activity

Abstract

N,O-carboxymethyl chitosan (N,O-CMC) was prepared from chitosan with chloroacetic acid as modifying agent and NaOH as binding-acid agent. 2-Hydroxypropyl dimethyl benzyl ammonium N,O-carboxymethyl chitosan chloride (HPDMBA-N,O-CMC) was obtained by the reaction between N,O-CMC and glycidyl dimethyl benzyl ammonium chloride (GDMBA) using NaOH as catalyst. The structures of chitosan derivatives were characterized by FT-IR, 1H NMR and gel permeation chromatography (GPC). The antimicrobial activity of HPDMBA-N,O-CMC was evaluated against a Gram-negative bacterium Escherichia coli (E. coli) and a Gram-positive bacterium Staphylococcus aureus (S. aureus). Compared with CTS, N,O-CMC and 2-hydroxypropyl dimethylbenzyl ammonium chitosan chloride (HPDMBA-CTS), HPDMBA-N,O-CMC had much stronger antimicrobial activity . When the substitution degree of carboxymethylation (DS of CM) was 0.856 and the substitution degree of quaternary ammonium group (DQ) was 0.573, the minimum inhibitory concentrations (MICs) of HPDMBA-CMC were 6.3 and 12.5 μg/mL against S. aureus and E. coli, respectively.