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Gram-negative Escherichia coli promotes deposition of polymer-capped silver nanoparticles in saturated porous media

Abstract

This study employed column tests to explore the co-transport of polyvinylpyrrolidone (PVP) polymer-capped silver nanoparticles (AgNPs) with Escherichia coli (E.coli) in model and natural porous medium systems, which respectively comprised of artificial groundwater and two glass beads (uncoated and iron-oxide-coated), and real groundwater and aquifer sand. Column results suggest insignificant effect of AgNP on E.coli transport in all systems. By contrast, the effect of E.coli on AgNP mobility differed between the model and the natural systems: E.coli promoted AgNP deposition in both glass beads, despite their contrasting electrical properties, but had insignificant effect on AgNP deposition in the natural system. Analyzing the filtrate of the AgNP-cell mixture in artificial groundwater suggests insignificant attachment of AgNP to the cell while the cell-released polymers altered the surface property of the nanoparticles. It was speculated that the insignificant effect of AgNP on E.coli mobility was due to the repulsive PVP-cell membrane interaction which prevented the nanoparticle to modify the cell surface property; while a surface modification by the cell-released polymer for both the AgNP and glass beads could lead to the promoting effect of E.coli on AgNP deposition. In natural system, sulfide in groundwater inhibited the attachment of the cell-released polymer on AgNP and consequently diminished the role of E.coli on AgNP mobility. This study highlighted the critical role of AgNP coating and outer membrane of bacteria in determining the eco-toxic impact of AgNP in porous media. Additionally, it emphasizes that the characterization of field physicochemistry and the identification of the governing environment factors is critical to better predicting the mobility and impact of silver nanoparticles in natural environment.

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Publication details

The article was received on 16 Jan 2018, accepted on 08 May 2018 and first published on 09 May 2018


Article type: Paper
DOI: 10.1039/C8EN00067K
Citation: Environ. Sci.: Nano, 2018, Accepted Manuscript
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    Gram-negative Escherichia coli promotes deposition of polymer-capped silver nanoparticles in saturated porous media

    F. Chen, X. Yuan, Z. Song, S. Xu, Y. Yang and X. Yang, Environ. Sci.: Nano, 2018, Accepted Manuscript , DOI: 10.1039/C8EN00067K

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