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 Zn2+ ions dissolution, cell type, and organic matter. Nanoparticle IC50 values determined for Bacillus subtilis and Escherichia coli were on the order of 0.3−0.5 and 15−43 mg/L (as Zn2+), while the IC50 for Zn2+ tolerant Pseudomonas putida was always >500 mg/L. Tannic acid decreased toxic...