Thermoresponsive Antibacterial Surfaces Switching from Bacterial Adhesion to Bacterial Repulsion

Herein, ene-functionalized dopamine is first coated onto a polyether sulfone membrane surface to introduce double bonds as anchoring sites for hydrogel film. Then, a hydrogel film is synthesized and simultaneously attached onto the membrane via photoinduced crosslinking copolymerization of N-isopropylacrylamide (NIPAAm) and methacryloxyethyltrimethyl ammonium chloride. The thickness of the hydrogel film can be well-controlled ranging from the nanometer to micrometer scales, which can retain the permeability of the membrane. Water contact angle and swelling tests demonstrate that the modified membrane shows thermoresponsive surface wettability. The quaternary ammonium salts in the hydrogel film can kill the attached bacteria efficiently and the dead bacteria can be detached by reducing the temperature below the lower critical solution temperature of poly(NIPAAm). The modified membrane also shows improved hemocompatibility, confirmed by prolonged clotting time and low hemolysis ratio. Hence, the designed thermoresponsive antibacterial hydrogel film with enhanced hemocompatibility has great potential to be applied in biomedical areas.