Why are Silver Nanoparticles More Toxic Than Bulk Silver? Towards Understanding the Dissolution and Toxicity of Silver Nanoparticles

摘要

The mass-transport to a spherical particle in solution is considered in the context of the mechanism ofoxygen reduction on silver nanoparticles. For small particles ( m) the reduction follows a two- proton, two-electron pathway due to the rapid diffusion of the intermediate hydrogen peroxide awayfrom the interface. Above this size threshold the hydrogen peroxide is further reduced to water. Thisswitch of mechanism is of importance when interpreting the dissolution of silver nanoparticles inaqueous media and their inherent toxicity. The release of H2O2 from nanoparticles but not bulk silvermay explain why silver nanoparticles are thought more toxic than their macroscopic counterparts.