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Molecular Mechanisms of ZnO Nanoparticle Dispersion in Solution: Modeling of Surfactant Association, Electrostatic Shielding and Counter Ion Dynamics.

ABSTRACT: Molecular models of 5 nm sized ZnO/Zn(OH)2 core-shell nanoparticles in ethanolic solution were derived as scale-up models (based on an earlier model created from ion-by-ion aggregation and self-organization) and subjected to mechanistic analyses of surface stabilization by block-copolymers. The latter comprise a poly-methacrylate chain accounting for strong surfactant association to the nanoparticle by hydrogen bonding and salt-bridges. While dangling poly-ethylene oxide chains provide only a limited degree of sterical hindering to nanoparticle agglomeration, the key mechanism of surface stabilization is electrostatic shielding arising from the acrylates and a halo of Na+ counter ions associated to the nanoparticle. Molecular dynamics simulations reveal different solvent shells and distance-dependent mobility of ions and solvent molecules. From this, we provide a molecular rationale of effective particle size, net charge and polarizability of the nanoparticles in solution.

SUBMITTER: Duchstein P

PROVIDER: S-EPMC4427181 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Molecular Mechanisms of ZnO Nanoparticle Dispersion in Solution: Modeling of Surfactant Association, Electrostatic Shielding and Counter Ion Dynamics.

Duchstein Patrick P Milek Theodor T Zahn Dirk D

PloS one 20150511 5

Molecular models of 5 nm sized ZnO/Zn(OH)2 core-shell nanoparticles in ethanolic solution were derived as scale-up models (based on an earlier model created from ion-by-ion aggregation and self-organization) and subjected to mechanistic analyses of surface stabilization by block-copolymers. The latter comprise a poly-methacrylate chain accounting for strong surfactant association to the nanoparticle by hydrogen bonding and salt-bridges. While dangling poly-ethylene oxide chains provide only a li ...[more]

PMID: 25962096

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Project description:An antivirulence approach targets bacterial virulence rather than cell viability in the antibiotic approach that can readily lead to drug resistance. Opportunistic human pathogen Pseudomonas aeruginosa produces a variety of virulence factors, and biofilm cells of this bacterium are much more resistant to antibiotics than planktonic cells. To identify novel inorganic antivirulence compounds, the dual screenings of thirty-six metal ions were performed to identify that zinc ions and ZnO nanoparticle inhibited the pyocyanin production and biofilm formation in P. aeruginosa without affecting the growth of planktonic cells. Moreover, zinc ion and ZnO nanoparticle markedly reduced the production of 2-heptyl-3-hydroxy-4(1H)-quinolone and siderophore pyochelin, while increased the production of another sideropore pyoverdine and swarming motility. Further, zinc ion and ZnO nanoparticle clearly suppressed hemolytic activity in P. aeruginosa. Transcriptome analyses showed that ZnO nanoparticle induced zinc cation efflux pump czc operon, porin genes (oprD and opdT), and Pseudomonas type III repressor A ptrA, while repressed pyocyanin-related phz operon, which partially explains the phenotypic changes. Overall, ZnO nanoparticle is a potential candidate for use in an antivirulence approach against persistent P. aeruginosa infection. P. aeruginosa Genechip Genome Array (Affymetrix, P/N 900339) was used in order to study the cells after the addition of ZnO nanoparticles. DNA microarray analysis with one biological replicate was performed with an Affymetrix system. P. aeruginosa was inoculated in 25 ml of LB medium in 250 ml shaker flasks with overnight cultures (1 : 100 dilution). Cells were cultured for 5 h with shaking at 250 rpm with and without ZnO nanoparticles (1 mM). Before sample collection, RNase inhibitor (RNAlater, Ambion, TX, USA) was added, and the cells were immediately chilled with dry ice and 95% ethanol (to prevent RNA degradation) for 30 s before centrifugation at 16,000 g for 2 min. The cell pellets were immediately frozen with dry ice and stored at –80°C. Total RNA was isolated using a Qiagen RNeasy mini Kit (Valencia, CA, USA).

Dataset Information

Molecular Mechanisms of ZnO Nanoparticle Dispersion in Solution: Modeling of Surfactant Association, Electrostatic Shielding and Counter Ion Dynamics.

Publications

Molecular Mechanisms of ZnO Nanoparticle Dispersion in Solution: Modeling of Surfactant Association, Electrostatic Shielding and Counter Ion Dynamics.

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