title: Availability of the basal planes of graphene oxide determines whether it is antibacterial.
abstract: There are significant controversies on the antibacterial properties of graphene oxide (GO): GO was reported to be bactericidal in saline, whereas its activity in nutrient broth was controversial. To unveil the mechanisms underlying these contradictions, we performed antibacterial assays under comparable conditions. In saline, bare GO sheets were intrinsically bactericidal, yielding a bacterial survival percentage of <1% at 200 μg/mL. Supplementing saline with ≤10% Luria-Bertani (LB) broth, however, progressively deactivated its bactericidal activity depending on LB-supplementation ratio. Supplementation of 10% LB made GO completely inactive; instead, ∼100-fold bacterial growth was observed. Atomic force microscopy images showed that certain LB components were adsorbed on GO basal planes. Using bovine serum albumin and tryptophan as well-defined model adsorbates, we found that noncovalent adsorption on GO basal planes may account for the deactivation of GO's bactericidal activity. Moreover, this deactivation mechanism was shown to be extrapolatable to GO's cytotoxicity against mammalian cells. Taken together, our observations suggest that bare GO intrinsically kills both bacteria and mammalian cells and noncovalent adsorption on its basal planes may be a global deactivation mechanism for GO's cytotoxicity.
authors.affiliation: CAS Key Laboratory of Materials for Energy Conversion, ‡Department of Materials Science and Engineering, §CAS Key Laboratory of Soft Matter Chemistry, and ∥Department of Polymer Science and Engineering, University of Science and Technology of China , 96 Jinzhai Road, Hefei, Anhui 230026, China.
authors.forename: Liwei
authors.initials: L
authors.lastname: Hui
authors.forename: Ji-Gang
authors.initials: JG
authors.lastname: Piao
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Auletta
authors.forename: Kan
authors.initials: K
authors.lastname: Hu
authors.forename: Yanwu
authors.initials: Y
authors.lastname: Zhu
authors.forename: Tara
authors.initials: T
authors.lastname: Meyer
authors.forename: Haitao
authors.initials: H
authors.lastname: Liu
authors.forename: Lihua
authors.initials: L
authors.lastname: Yang
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001412:Bacillus subtilis / Q000187:drug effects; D002417:Cattle; D004926:Escherichia coli / Q000187:drug effects; D006108:Graphite / Q000737:chemistry* / Q000494:pharmacology*; D056945:Hep G2 Cells; D006801:Humans; D008826:Microbial Sensitivity Tests; D008856:Microscopy, Fluorescence; D010087:Oxides / Q000737:chemistry* / Q000494:pharmacology*; D012710:Serum Albumin, Bovine / Q000737:chemistry; D012965:Sodium Chloride
chemical_list: D000900:Anti-Bacterial Agents; D010087:Oxides; D012710:Serum Albumin, Bovine; D012965:Sodium Chloride; D006108:Graphite