pH-activated antibacterial coating switching from polyzwitterion to polycation

Stimuli-responsive surfaces have the potentials to solve the trade-off between biocompatibility and antibacterial performance by switching specific function on-demand, which makes them a promising option for developing biocompatible antibacterial surfaces. In this study, a pH-responsive antibacterial surface was created by grafting polycationic brushes and forming an acid-sensitive zwitterionic structure through a spontaneous amino-yne click reaction. Under physiological conditions, the zwitterionic structure provided the surface with good biocompatibility, as confirmed by lower hemolysis and cytotoxicity, as well as low adhesion and activation of platelets. When bacteria begin to colonize on the biomaterial surface, the decrease in local pH can break the acid-sensitive enamine bond and expose the polycations, activating the bactericidal activity. The good and on demand bactericidal activity was verified by the stimulated and authentic bacterial infection conditions. This study highlights the potential of stimuli-responsive zwitterionic surfaces as a valuable option for infection-resistant medical devices .