Interrogate the antibacterial activities of nano graphene oxide sheets

Nanographene oxide (GO) sheets or GO nanosheets have been regarded as promising antimicrobial materials in recent years. In the present work, we intended to investigate the effect of nano GO sheets on antibiotic-resistant bacteria or “superbugs”, Klebsiella pneumoniae (K. pneumoniae). Wild-type and capsule-deficient K. pneumoniae were used as model bacteria in this study. The difference between the wild-type and capsule-deficient bacteria is that the thick polysaccharide capsular layer surrounded the wild-type bacteria that can protect the bacteria from environmental stresses has been genetically removed in the capsule-deficient bacteria. Cell viability was evaluated using both a colony counting assay and a fluorescence technique. Both methods demonstrated that nano GO sheets had no observable effects on the viability of either the wild-type or the capsule-deficient K. pneumoniae. The results indicate that nano GO sheets cannot be regarded as a broad-spectrum antimicrobial material to kill bacteria.