Original Article
Clinical Nanomedicine
Synthesis and effect of silver nanoparticles on the antibacterial activity of different antibiotics against Staphylococcus aureus and Escherichia coli

https://doi.org/10.1016/j.nano.2007.02.001Get rights and content

Abstract

Silver nanoparticles (Ag-NPs) have been known to have inhibitory and bactericidal effects. Resistance to antimicrobial agents by pathogenic bacteria has emerged in recent years and is a major health problem. The combination effects of Ag-NPs with the antibacterial activity of antibiotics have not been studied. Here, we report on the synthesis of metallic nanoparticles of silver using a reduction of aqueous Ag+ ion with the culture supernatants of Klebsiella pneumoniae. Also in this article these nanoparticles are evaluated for their part in increasing the antimicrobial activities of various antibiotics against Staphylococcus aureus and Escherichia coli. The antibacterial activities of penicillin G, amoxicillin, erythromycin, clindamycin, and vancomycin were increased in the presence of Ag-NPs against both test strains. The highest enhancing effects were observed for vancomycin, amoxicillin, and penicillin G against S. aureus.

Section snippets

Synthesis of Ag-NPs

Colloidal Ag-NPs solution was prepared following the method already described [8], [9]. Müller-Hinton medium was prepared, sterilized, and inoculated with a fresh growth of test strain. The cultured flasks were incubated at 37°C for 24 hours. After the incubation time the culture was centrifuged at 12,000 rpm and the supernatant was used for the synthesis of Ag-NPs. K. pneumoniae culture supernatant was separately added to the reaction vessels containing silver nitrate at a concentration of 10–3

Results and discussion

Ag-NPs were synthesized from Ag+ ions by treating the supernatant of K. pneumonia. The appearance of a yellowish brown color in the reaction vessels suggested the formation of Ag-NPs [10]. The supernatant of the K. pneumonia culture changed the solution to a brownish color upon the completion of the 5-minute reaction with Ag+ (Figure 1). The Ag-NPs were characterized by UV-vis spectroscopy. The technique outlined above has proved to be very useful for the analysis of nanoparticles [11], [12],

Acknowledgments

This research was supported by the Medical Nanotechnology Research Center, Faculty of Pharmacy, Medical Sciences/University of Tehran, Tehran, Iran.

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