▎ 摘　　要

Graphene nanosheets are highly recognized for their utility toward the development of biomedical device applications. The present study investigated the antibacterial efficiency of graphene nanosheets against four types of pathogenic bacteria. Graphene nanosheets are synthesized by a hydrothermal approach (under alkaline conditions using hydrazine hydrate). UV-vis and X-ray diffraction show a maximum absorbance at 267 nm and appearance of new broad diffraction peak at 26 degrees, which ensures the reduction of graphene oxide into graphene nanosheets. Stretching and bending vibrations of C-C bonds, chemical states, disorder, and defects associated with the graphene nanosheets are evaluated in comparison with graphene oxide. The minimum inhibitory concentration (MIC) of graphene nanosheets against pathogenic bacteria was evaluated by a microdilution method. MICs such as 1 mu g/mL (against Escherichia coli and Salmonella typhimurium), 8 mu g/mL (against Enterococcus faecalis), and 4 mu g/mL (against Bacillus subtilis) suggest that graphene nanosheets have predominant antibacterial activity compared to the standard antibiotic, kanamycin. Measurement of free radical modulation activity of graphene nanosheets suggested the involvement of reactive oxygen species in antibacterial properties.