Surface Grafted N-Oxides have Low-Fouling and Antibacterial Properties

Low-fouling materials are often generated by surface zwitterionization with polymers. In this context, poly-N-oxides have recently attracted considerable attention as biomimetic stealth coatings with low protein adsorption. Herein, this study reports that poly-N-oxides can be grafted from plasma-activated plastic base materials. The resulting hydrophilic surfaces have low-fouling properties in bacterial suspensions and suppress the formation of biofilms. Moreover, efficient antibacterial activity against Gram-negative and Gram-positive bacteria caused by release of reactive oxygen species is observed. The latter effect is specific for polymeric N-oxides and is most likely triggered by a reductive activation of the N-oxide functionality in the presence of bacteria. In contrast to other zwitterionic polymers, N-oxides combine thus low-fouling (stealth) properties with antibacterial activity. The bioactive N-oxide groups can be regenerated after use by common oxidative disinfectants. Poly-N-oxides are thus attractive antibacterial coatings for many base materials with a unique combined mechanism of action.