Antibacterial activities and mechanisms of fluorinated graphene and guanidine-modified graphene†
The antibacterial properties and mechanism of three types of graphene derivatives, graphene oxide (GO), fluorinated graphene (FG), and guanidine-modified graphene (PHGH-G), were comparatively studied. The PHGH-G nano-sheets were synthesized using the FG as a substrate. The results obtained from atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM) demonstrated that antibacterial activity of FG sheets, similar to that of GO, depends on how they interact with bacterial cells. In contrast to GO and FG, the PHGH-G with a low grafting ratio, about 2%, had a high antibacterial activity while the nanosheets applied to the culture medium at a concentration of 20 μg mL−1 can lead to a 99.9% viability loss in Escherichia coli (E. coli). The local damage to E. coli cells was induced by PHGH-G upon contact, resulting in the collapse of bacteria. It is considered that the strong interaction between PHGH-G and the membrane of E. coli cells attracts the cells to the surface of the nano sheets, and then the local bonded PHGH oligomers with a high concentration destroy the cell membranes.