Enhancement of a zwitterionic chitosan derivative on mechanical properties and antibacterial activity of carboxymethyl cellulose-based films

A type of zwitterionic chitosan derivative, N-2-hydroxylpropyl-3-trimethylammonium-O-carboxymethyl chitosan (HTCMCh), was synthesized and introduced into carboxymethyl cellulose (CMC)-based films as a film strength enhancer and antibacterial agent. The influencing factors include degree of substitution (DS) and m_HTCMCh/m_CMC. Their influences on mechanical properties, thermal stability, antibacterial activities, microstructures, transmittance, and wettability of the CMC-based films were studied. It was found that HTCMCh improves the tensile strength (by 9.0–130.9%), Young's modulus (47.8–351.6%), and elongation at break (90.8–280.8%) of CMC/HTCMCh films simultaneously, depending on the DS and mass content of HTCMCh. However, the HTCMCh shows little influence on microstructure and thermal stability of CMC/HTCMCh films. Satisfactorily, CMC/HTCMCh films show strong antibacterial activities against E. coli and S. aureus and are nontoxic to fibroblast HFF-1 cells. Pork packaging experiments demonstrated that CMC/HTCMCh_10%,0,58 film could significantly inhibit bacterial growth, indicating that the HTCMCh-doped CMC films could be used as food packaging materials.