Silver nanoparticles - wolves in sheep's clothing?

Silver nanoparticles (Ag NPs) are one of the most widely utilized engineered nanomaterials (ENMs) in commercial products due to their effective antibacterial activity, high electrical conductivity, and optical properties. Therefore, they have been one of the most intensively investigated nanomaterials in terms of their toxic effects on humans and the environment. It has become clear during recent years that nanomaterials can behave unexpectedly due to new and unique characteristics when their particle size reaches the nanoscale (1-100 nm). Consequently, their effect on human health and the environment has been hard to predict. Widespread applications increase the chances of public and environmental exposure to Ag NPs and have thereby increased concerns regarding the potential adverse effects of Ag NPs on human health and environmental safety. To fully understand and predict possible health effects following exposure to Ag NPs, information about the mechanisms for their cytotoxicity and genotoxicity is necessary. The present paper attempts to review the cellular and molecular mechanisms behind Ag NP toxicity. In addition, the role of silver ions in the toxicity of Ag NPs is discussed.