The Science Nano Difference

THE SCIENCE: Nano Difference

Bulk gold is inert, but microscopic gold particles behave differently. Below 100 nanometers, the ratio of surface atoms to interior atoms spikes, exposing reactive sites that bulk gold keeps buried. This size-dependent reactivity is why gold can sit unchanged for millennia and then suddenly interact with living cells when broken down. The smaller the particle, the greater its biological influence. But if shrinking something inert makes it reactive, what determines whether that reactivity heals or harms?