title: Synergistic photocatalytic inactivation mechanisms of bacteria by graphene sheets grafted plasmonic AgAgX (X = Cl, Br, I) composite photocatalyst under visible light irradiation.
abstract: By coupling graphene sheet and plasmonic photocatalysis technologies, a series of AgAgX/RGOs (X = Cl, Br, I; RGO = reduced graphene oxide) composites were prepared and found to be efficient antimicrobial agents for water disinfection upon visible light. Attributed to the efficient charge transfer by RGO sheets, the optimum AgAgBr/0.5% RGO could completely inactivate 2 × 10(7) cfu mL(-1) of Escherichia coli within 8 min, much faster than bare AgAgBr within 35 min. The synergistic antimicrobial mechanism of AgAgBr/0.5% RGO was studied by Ag(+) ions release evaluation, radical scavengers study, and radical determination. The enhanced photocatalytic activity of irradiated AgAgBr/0.5% RGO originated from the synergistic activities of its three components including Ag, AgBr and RGO, and the proposed mechanisms contained enhanced attraction by RGO followed by two pathways: primary oxidative stress caused by plasma induced reactive species like H2O2 and bactericidal effect of released Ag(+) ions. Furthermore, characterization of E. coli cells using SEM, fluorescent microscopy, and cytoplasmic substance leakage illustrated that VL irradiated AgAgBr/0.5% RGO could not only cause metabolic dysfunction but also destroy the cell envelope and biomolecular, while irradiated Ag(+) ions play a differential bactericidal action with a limited metabolic injury and no cell-membrane damage. The present work provides an efficient water disinfection technology and also opens a new idea in studying the antimicrobial mechanism of plasmonic photocatalyst.
authors.affiliation: School of Life Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong Special Administrative Region.
authors.forename: Dehua
authors.initials: D
authors.lastname: Xia
authors.affiliation: Institute of Environmental Health and Pollution Control and School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China. Electronic address: antc99@gdut.edu.cn.
authors.forename: Taicheng
authors.initials: T
authors.lastname: An
authors.affiliation: Institute of Environmental Health and Pollution Control and School of Environmental Science and Engineering, Guangdong University of Technology, Guangzhou 510006, China.
authors.forename: Guiying
authors.initials: G
authors.lastname: Li
authors.affiliation: School of Life Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong Special Administrative Region.
authors.forename: Wanjun
authors.initials: W
authors.lastname: Wang
authors.affiliation: Centre for Clean Environment and Energy, Gold Coast Campus, Griffith University, Queensland 4222, Australia.
authors.forename: Huijun
authors.initials: H
authors.lastname: Zhao
authors.affiliation: School of Life Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong Special Administrative Region. Electronic address: pkwong@cuhk.edu.hk.
authors.forename: Po Keung
authors.initials: PK
authors.lastname: Wong
mesh_terms: D002384:Catalysis; D004926:Escherichia coli / Q000187:drug effects; D006108:Graphite; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008027:Light; D012834:Silver / Q000494:pharmacology; D018030:Silver Compounds / Q000494:pharmacology*
chemical_list: D018030:Silver Compounds; D012834:Silver; D006108:Graphite; D006861:Hydrogen Peroxide
keywords: Ag(+) ions; Bacterial inactivation; Plasmonic photocatalyst; Synergistic mechanism; Visible light