Cheap synthesis offers edge over gold particles for biomedicine and solar cells. In the realm of nanoparticles, gold reigns supreme. Stable and easy to handle, gold nanoparticles have been used to image cells, deliver drugs and detect disease biomarkers. Silver, by contrast, has suffered from a tarnished reputation, because it is more easily oxidized than gold. It is cheaper, but its nanoparticles degrade far too easily for most uses. Two teams of chemists are now burnishing silver’s status. They have independently developed methods to make robust silver nanoparticles on a large scale — and have worked out what makes them...