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14-03-2012 | Infectious disease | Article

Silver nanoparticles ‘active against oral Candida infection’


Free abstract

MedWire News: Silver nanoparticles have shown promise as a treatment for oral Candida infection, Portuguese researchers say.

Their study found that silver nanoparticles had antifungal activity against Candida albicans and Candida glabrata, which cause oral thrush and dental stomatitis and for which there are limited therapeutic options.

Mariana Henriques (University of Minho, Braga) and team evaluated the in vitro antifungal activity of silver nanoparticles in colloidal suspensions. These particles are already known to act on a broad range of microbial targets, and smaller particles are thought to have greater activity than larger particles.

Henriques et al first synthesized silver colloidal nanoparticles in three sizes (5, 10, and 60 nm) and then added them to yeast cultures, grown on artificial saliva biofilms to mimic in vivo conditions in the oral cavity.

Results, published in Letters in Applied Microbiology, showed that both Candida species were susceptible to all the silver nanoparticles tested at very low concentrations (0.4-3.3 µg/mL). The greatest efficacy was achieved against C. glabrata biofilms, achieving around a 90% reduction in yeast mass at a silver concentration of 108 µg/mL.

The three sizes of nanoparticles were equally effective, the researchers report. All of the tested suspensions brought about a significant reduction in the mean number of yeast cells at a silver concentration of 108 µg/mL or greater.

In addition, the choice of stabilizing agent - either ammonia or polyvinylpyrrolidone - did not interfere with antifungal activity of the solutions against either of the Candida biofilms.

In their discussion, Henriques et al note that oral Candida infections are common, especially in denture wearers, and are increasingly developing resistance to existing antifungal therapy.

Alternative approaches are therefore needed, they note, and the current results support silver nanoparticles as a potential therapeutic option. "As the nanoparticles are relatively stable in liquid medium, they could be developed into a mouthwash solution in the near future," say the authors in a press statement.

Their paper concludes: "On the basis of these findings, additional investigations with silver colloidal nanoparticles will be needed regarding their therapeutic potential, namely to assess formulation and delivery means."

MedWire ( is an independent clinical news service provided by Springer Healthcare Limited. © Springer Healthcare Ltd; 2012

By Joanna Lyford