Issue 9, 2021

Emerging investigator series: chemical transformation of silver and zinc oxide nanoparticles in simulated human tear fluids: influence of biocoronae

Abstract

With the rapid development of nanotechnology, personal care products with silver nanoparticles (Ag-NPs) or zinc oxide nanoparticles (ZnO-NPs) are being widely used because of their superior antibacterial efficacies. Biological fluids would thus inevitably interact with Ag-NPs or ZnO-NPs. Human tear fluid is an important model that was ignored in past studies, restricting the comprehensive understanding of the stability and health risks of Ag-NPs and ZnO-NPs. Herein, two simulated tear fluid models were examined, allowing us to understand potential transformations that can affect the properties and toxicity of Ag-NPs and ZnO-NPs. Both Ag-NPs and ZnO-NPs exhibited high chemical stability in the simulated tear fluid containing proteins even after an incubation time of 168 h due to the formation of biocoronae on the particles, resulting in inferior antibacterial activities of Ag-NPs and ZnO-NPs to E. coli. Nevertheless, Ag-NPs and ZnO-NPs could gradually transform into AgCl and Zn5(CO3)2(OH)6 respectively in the simulated tear fluid without protein, wherein AgCl or Zn5(CO3)2(OH)6 accounted for 59.7% of silver or 91.7% of zinc through a selective dissolution method established in this study. The size of AgCl particles was far smaller than that of pristine Ag-NPs, whereas Zn5(CO3)2(OH)6 exhibited a needle-crossed morphology with a large size compared to pristine ZnO-NPs. An enhanced antibacterial efficacy was observed for the transformed Ag-NPs relative to that for pristine Ag-NPs, since high concentrations of dissolved silver were detected in the culture medium with the transformed Ag-NPs. Compared to pristine ZnO-NPs, in contrast, the transformed ZnO-NPs showed moderate antibacterial activity to E. coli. In total, the chemical stability of Ag-NPs and ZnO-NPs in the simulated tear fluid was highly affected by the protein, which would further influence their antibacterial efficacies.

Graphical abstract: Emerging investigator series: chemical transformation of silver and zinc oxide nanoparticles in simulated human tear fluids: influence of biocoronae

Supplementary files

Article information

Article type
Paper
Submitted
20 Jun 2021
Accepted
15 Aug 2021
First published
16 Aug 2021

Environ. Sci.: Nano, 2021,8, 2430-2440

Emerging investigator series: chemical transformation of silver and zinc oxide nanoparticles in simulated human tear fluids: influence of biocoronae

L. Li, A. U. Khan, X. Zhang, X. Qian and Y. Wang, Environ. Sci.: Nano, 2021, 8, 2430 DOI: 10.1039/D1EN00566A

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