We developed a time-resolved high throughput screening (HTS) method utilizing an Escherichia coli genome-wide knockout clone library to study zinc containing nanomaterials (Zn-eNMs) interactions. The library was screened against nanoscale zerovalent zinc (nZn), nanoscale zinc oxide (nZnO), and zinc chloride (ZnCl2) salt for reference. Initial screening over 24 hours identified 173 sensitive clones, which fell into two groups, early and late responders. Furthermore, sensitivity profiles differed between Zn-eNMs and ZnCl2. Secondary screening of sensitive clones at 6 and 24 hr, suggested bacterial toxicity changed from pathways related to general metabolic function, transport, signaling, and metal homeostasis to membrane synthesis pathways. To confirm these results, reverse transcription quantitative PCR (RT-qPCR) of a subset of genes showed transient up-regulation at either 6 or 24 hr. Unlike single time point, mortality-based assays like IC50, our time resolved approach captures dynamic nano-bio interactions and allows investigation of all potential nanotoxicity mechanisms in parallel.

Time-dependent nanotoxicity mechanisms in <i>Escherichia coli</i> revealed by a genome-wide investigation

245th National Meeting (2013)

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Time-dependent nanotoxicity mechanisms in Escherichia coli revealed by a genome-wide investigation