Wrinkled Surface-Mediated Antibacterial Activity of Graphene Oxide Nanosheets.

Surface wrinkles are commonly observed in large-scale of graphene films. As a new feature, the wrinkled surface of graphene films may directly affect bacterial viability by means of various interactions of bacterial cells with graphene sheets. In the present study, we introduce a wrinkled surface geometry of graphene oxide (GO) thin films for antibacterial application. Highly wrinkled GO films were formed by vacuum filtration of a GO suspension through a prestrained filter. Several types of wrinkled GO surfaces were obtained with different roughness grades determined by root-mean-square values. Antibacterial activity of the fabricated GO films toward three different bacterial species, Escherichia coli, Mycobacterium smegmatis, and Staphylococcus aureus, was evaluated in relation to surface roughness. Because of their nanoscopically corrugated nature, the wrinkled GO films exhibited excellent antibacterial properties. On the basis of our detailed observations, we propose a novel concept of the surrounded contact-based mechanism for antimicrobial activity of wrinkled GO films. It postulates formation of a mechanically robust GO surface "trap" that prompts interaction of bacteria with the diameter-matched GO sink, which results in substantial damages to the bacterial cell membrane. We believe that our approach uncovered a novel use of a promising two-dimensional material for highly effective antibacterial treatment.