Identification of protein corona on graphene oxide in B medium

As antimicrobials, graphene materials (GMs) may have advantages over traditional antibiotics due to their physical mechanisms of action which ensure less chance of development of microbial resistance. However, the fundamental question as to whether the antibacterial mechanism of GMs originates from penetration by their sharp edges or wrapping of the cell membrane, or from a combination of these and other mechanisms, remains controversial. In this study, we show both experimentally and theoretically that GMs with high surface oxygen content (SOC) predominantly attach in parallel to the bacterial cell surface when in the suspension phase. The interaction mode shifts to perpendicular interaction when the SOC reaches a threshold of ~ 0.3 (the atomic percent of O in the total atoms). However, neither mode necessarily kills bacteria. Rather, bactericidal activity depends on the interaction of GMs with surrounding biomolecules. Proteomic study shows that protein corona forms on the surface graphene oxide in LB medium, thus explain the different antibacterial activity in different culture medium.