Evaluating the Potential for Resistance Evolution in E. coli Exposed to Silver Nanowires

Department

North Carolina A&T State University

Document Type

Poster

Publication Date

4-17-2026

Abstract

Silver nanoparticles are potent antimicrobials against Gram-negative and Gram-positive bacteria, making them promising for healthcare use. However, Escherichia coli (E. coli) can evolve resistance to standard silver nanoparticles after repeated exposure (Graves et al. 2015), raising concerns about long-term efficacy. Silver nanowires, with sharp ends that may enhance membrane penetration, could provide both physical and chemical antimicrobial activity, potentially slowing resistance. This study tested whether E. coli could evolve resistance to silver nanowires. We hypothesized that their dual mode of action would create an evolutionary trap, preventing adaptation. Using E. coli K-12 MG1655, we determined the minimum inhibitory concentration (MIC) of silver nanowires as 10 mg/mL, then conducted a 21-day experimental evolution study at the sub-MIC 8 mg/mL. Cultures were serially passaged daily under this condition. Post- experiment MIC assays showed that E. coli evolved increased resistance. Whole-genome sequencing identified mutations in cusS, a histidine kinase regulating the copper-silver efflux pump. These findings suggest that even nanostructured silver can be overcome by bacterial adaptation. Future work will test additional nanoparticle shapes on high-touch surfaces. If resistance proves less likely in such contexts, silver-coated nanosurfaces may still hold promise for healthcare applications.

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