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Download fileSelf-Damaging Aerobic Reduction of Graphene Oxide by Escherichia coli: Role of GO-Mediated Extracellular Superoxide Formation
journal contribution
posted on 2018-10-02, 00:00 authored by Huiru Zhao, Chengdong Zhang, Yaqi Wang, Wei Chen, Pedro J. J. AlvarezMicrobial
reduction of graphene oxide (GO) under aerobic conditions
is poorly understood despite its critical role in changing GO toxicity
and environmental fate. Here we show that 20 mg/L GO interacts with
the membrane-bound cytochrome c of E. coli in saline, shuttling electrons from the respiratory chain to extracellular
molecular oxygen. This results in the formation of superoxide anions
(O2•–), which in turn reduce GO
in 30 min. The critical role of superoxide was demonstrated by impeding
GO reduction upon addition of superoxide dismutase, or by carrying
out experiments under strictly anaerobic conditions that preclude
O2•– formation. Coating GO with
bovine serum albumin also stopped GO reduction, which indicates the
need for direct contact between GO and the cell membrane. Cell death
was observed as a consequence of GO bioreduction. Apparently, electron
shuttling by GO (via membrane contact) interrupts the respiratory
chain and induces oxidative stress, as indicated by a 20% decrease
in electron transport activity and an increase in intracellular reactive
oxygen species. This novel antimicrobial mechanism could be relevant
to assess GO stability and biocompatibility, and informs potential
applications for microbial control.
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Keywords
superoxide dismutasesuperoxide anionsGO-Mediated Extracellular Superoxide Formation Microbial reductionnovel antimicrobial mechanismgraphene oxideformationGraphene Oxidecell membranemembrane contactEscherichia coliSelf-Damaging Aerobic Reductionoxidative stressintracellular reactive oxygen speciesmembrane-bound cytochrome croleelectron transport activity30 mincell deathserum albumin