Antibacterial cellulose membrane via one-step covalent immobilization of ammonium/amine groups

This work describes a direct covalent linking of quaternary ammonium salts (QAS) and aminoalkyl groups onto regenerated cellulose (RC) membrane surface to prepare contact active antibacterial membrane materials. The membranes were prepared via alkoxysilane polycondensation reaction with three silane coupling agents, including trimethoxysilylpropyl trimethyl ammonium chloride (QASC0), trimethoxysilylpropyl octadecyldimethyl ammonium chloride (QASC18) and 3-aminopropyltrimethoxysilane (APS). FTIR, XPS, FESEM and AFM were used to characterize the chemical composition and surface morphology of the resulted RC-QASC0, RC-QASC18 and RC-NH2 membranes. Membrane surface charge properties were measured by the streaming potential method. Static water contact angle (WCA) and permeation flux were measured to investigate surface wettability and membrane permeability. Escherichia coli and Staphylococcus aureus were used as model bacteria to evaluate the antibacterial properties of membranes. The bacterial cell viability on membrane surfaces was evaluated by the dynamic shake flask test and the bacterial anti-adhesion properties were evaluated by confocal laser scanning microscopy (CLSM) measurements following the immersion test. RC-QASC18 and RC-NH2 membranes show strong antibacterial and bacteria anti-adhesion properties. Both membranes have a bacteria killing ratio over 99.5%. The stability study shows that the antibacterial property of modified membranes is robust in a wide range of pH and temperature conditions.