Embodiments of the present invention relate to a metastable silver nanoparticle composite, a process for its manufacture, and its use as a source for silver ions. In various embodiments, the composite comprises, consists essentially of, or consists of metastable silver nanoparticles that change shape when exposed to moisture, a stability modulant that controls the rate of the shape change, and a substrate to support the silver nanoparticles and the modulant.
