Surface modification of polytetrafluoroethylene membrane and lysozyme immobilization

Polytetrafluoroethylene membrane was modified via self-polymerization of dopamine, and then lysozyme was immobilized on the surface of membrane, aiming at preparing waterproof and breathable antibacterial materials. The results show that with modification time increased, the surface animo groups density of membrane increases while the contact angle and gas flux decline. Animo group density and contact angle reach saturation after 12 h. With dopamine concentration increased within 0.5 mg/mL, the surface animo groups density of membrane increases while the contact angle declines, and they are substantially unchanged when the dopamine concentration exceeds 1 mg/mL. Effects of immobilization conditions on enzyme activity were measured by hydrolyzing micrococcus lysodeikticu cells. The optimum conditions are 0.1% glutaraldehyde, 2 mg/mL lysozyme, pH7.0 and 8 h reaction time. The maximum activity of immobilized lysozyme is 3.5 U/cm². The results of FT-IR, SEM and XPS confirm the presence of polydopamine coating, and an antibacterial ratio of 89% is obtained.