Bacteria-responsive surfaces popularly exert their smart antibacterial activities by bacteria-triggered delivery of antibacterial agents; however, the antibacterial agents should be additionally reloaded for the renewal of these surfaces. Herein, a reversible, nonleaching bacteria-responsive antibacterial surface is prepared by taking advantage of a hierarchical polymer brush architecture. In this hierarchical surface, a pH-responsive poly(methacrylic acid) (PMAA) outer layer serves as an actuator modulating the surface behavior on demand, while antimicrobial peptides (AMP) are covalently immobilized on the inner layer. The PMAA hydration layer renders the hierarchical surface resistant to initial bacterial attachment and biocompatible under physiological conditions. When bacteria colonize the surface, the bacteria-triggered acidification allows the outermost PMAA chains to collapse, therefore exposing the underlying bactericidal AMP to on-demand kill bacteria. In addition, the dead bacteria can be released once the PMAA chains resume their hydrophilicity because of the environmental pH increase. The functionality of the nonleaching surface is reversible without additional reloading of the antibacterial agents. This approach provides a new methodology for the development of smart surfaces in a variety of practical biomedical applications.
Keywords: bacteria-responsive; cationic antimicrobial peptides; hierarchical architecture; pH-responsive polymer; smart surfaces.