Stability, bioavailability, and bacterial toxicity of ZnO and iron-doped ZnO nanoparticles in aquatic media.
The stability and bioavailability of nanoparticles is governed by the interfacial properties that nanoparticles acquire when immersed in a particular aquatic media as well as the type of organism or cell under consideration. Herein, high-throughput screening (HTS) was used to elucidate ZnO nanoparticle stability, bioavailability, and antibacterial mechanisms as a function of iron doping level (in the ZnO nanoparticles), aquatic chemistry, and bacterial cell type. ζ-Potential and aggregation state of dispersed ZnO nanoparticles was strongly influenced by iron doping in addition to electrolyte composition and dissolved organic matter; however, bacterial inactivation by ZnO nanoparticles was most significantly influenced by Zn(2+) ions dissolution, cell type, and organic matter. Nanoparticle IC(50) values determined for Bacillus subtilis and Escherichia coli were on the order of 0.3-0.5 and 15-43 mg/L (as Zn(2+)), while the IC(50) for Zn(2+) tolerant Pseudomonas putida was always >500 mg/L. Tannic acid decreased toxicity of ZnO nanoparticles more than humic, fulvic, and alginic acid, because it complexed the most free Zn(2+) ions, thereby reducing their bioavailability. These results underscore the complexities and challenges regulators face in assessing potential environmental impacts of nanotechnology; however, the high-throughput and combinatorial methods employed promise to rapidly expand the knowledge base needed to develop an appropriate risk assessment framework.
Department of Civil & Environmental Engineering, California NanoSystems Institute, University of California-Los Angeles (UCLA), Los Angeles, California, 90095-1593, USA.
Minghua
M
Li
Suman
S
Pokhrel
Xue
X
Jin
Lutz
L
Mädler
Robert
R
Damoiseaux
Eric M V
EM
Hoek
D001412:Bacillus subtilis / Q000187:drug effects; D001419:Bacteria / Q000187:drug effects*; D004926:Escherichia coli / Q000187:drug effects; D007501:Iron / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity; D053768:Metal Nanoparticles / Q000737:chemistry / Q000633:toxicity* / Q000648:ultrastructure; D050296:Microbial Viability / Q000187:drug effects; D046529:Microscopy, Electron, Transmission; D016958:Pseudomonas putida / Q000187:drug effects; D018570:Risk Assessment; D014874:Water Pollutants, Chemical / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity; D015034:Zinc Oxide / Q000737:chemistry / Q000378:metabolism* / Q000633:toxicity
D014874:Water Pollutants, Chemical; D007501:Iron; D015034:Zinc Oxide