Silver's antibacterial properties: it's all in the ions

“We could not get consistent results,” he said. “It was very frustrating and really weird.” Zongming Xiu, a Rice postdoctoral researcher recently authored a paper describing his experiment. Xiu and his colleagues set out to understand why silver nanoparticles, widely used as an antibacterial agent, work. The long-held belief has been that the silver particles themselves are harmful to the bacteria, and Xiu's "weird" experiment tried to show that smaller particles are more toxic. Xiu performed the experiment in an oxygen-free environment, to prevent ion-releasing oxidization, and found that toxicity dropped almost to zero. In the end he found that the particles themselves are not harmful -- silver ions are the culprit. "These findings suggest that the antibacterial application of silver nanoparticles could be enhanced and environmental impacts could be mitigated by modulating the ion release rate, for example, through responsive polymer coatings," Xiu said.