Antimicrobial Effects of Silver and Gold Nanoparticles Alone, and Functionalized with Ampicillin
Helmstetter, Nicholas J.
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There is a need for the development of effective and novel antimicrobials as alternatives for the control of antibiotic resistant pathogens. Certain nanomaterials like metallic nanoparticles (NPs) show antimicrobial activity and may be an inexpensive and effective solution. The goals of this study were to first demonstrate the antimicrobial effects of NPs then to explore the synergistic antimicrobial effect of ampicillin bound to NPs (NPs-amp). Gold and silver NPs (Au-NPs, Ag-NPs) 5 nm in diameter were added to Luria- Bertani (LB) agar at a concentration of 1.2 x 1016 NPs/mL. To demonstrate antibacterial activity, Escherichia coli (E. coli) was plated onto Petri dishes containing NPs, grown overnight and then counted. The count for E. coli grown in the absence of NPs was 9 log10 Colony Forming Units/mL (CFU/mL). Growth on plates containing Au-NPs was 8.98 log10 CFU/mL, while the count for E. coli grown in the presence of Ag-NPs was 4.49 log10 CFU/mL. Bacteria grown in the presence of Ag-NPs showed a significantly lower rate of survival compared to control plates while E. coli grown on plates containing Au-NPs did not. For the second component of the study, ampicillin was functionalized, or bound to the surface of the NPs. E. coli grown in absence of NPs-amp had a CFU/mL of 8.81 log10. Interestingly, there were no CFUs of E. coli in the presence of Ag-NPs-amp or Au- NPs-amp. These results suggest that Ag-NPs bound to bactericidal agents may be useful as effective and novel agents for use in the control of bacterial pathogens.