Preparation, characterization and antibacterial properties of cellulose membrane containing N-halamine

Polyethylenimine (PEI), a type of water-soluble chain polymer containing a great number of primary, secondary and tertiary amine groups in the molecule, was used as an N-halamine precursor. It was grafted onto dialdehyde cellulose membrane (DCM) followed by chlorination to prepare a novel N-halamine antibacterial cellulose membrane (Cl–PEI–DCM). The appropriate conditions affecting the aldehyde content of DCM and the active chlorine (Cl⁺) content of Cl–PEI–DCM were systematically studied at oxidation, grafting and chlorination stages, respectively. The structure and properties of the samples were investigated by SEM, ATR–FTIR, XRD, XPS, light transmittance measurements and tensile tests. The stability and rechargeability of the Cl–PEI–DCM were evaluated, and its antibacterial activity was tested against S. aureus and E. coli. Results showed that the Cl⁺ content of the chlorinated samples was strongly dependent on the aldehyde content of DCM and PEI concentration. Under the optimum testing condition, the Cl⁺ content of the Cl–PEI–DCM reached 1.30 wt%. The hydroxyl groups on the cellulose membrane were changed to aldehyde groups and the successful introduction of PEI and N–Cl bond were confirmed. The 1.30 wt% Cl–PEI–DCM exhibited high antibacterial activity against both S. aureus and E. coli, which can completely inactivate two bacterial pathogens within 5 min even after 15 days of storage. Moreover, the Cl–PEI–DCM membrane displayed good stability, rechargeability, transparency and high mechanical strength. These results demonstrated that the Cl–PEI–DCM can be considered as a visualized wound dressing material or antibacterial shoe insole.