Hydroxyapatite/platinum bio-photocatalyst: a biomaterial approach to self-cleaning

A bio-inspired approach to photocatalysis with a selection of biologically acceptable building blocks that can be activated by non-toxic visible light is a direction of research for the design of advanced, biomaterials that are able to induce self-cleaning. Here we show that a combination of hydroxyapatite (HAp) with platinum (Pt-0 and Ptn+) is suitable to form a novel photocatalytically active material. The so-formed hybrid semiconductor/metallic nanocomposites made of apatite plates with Pt metallic nanoparticles attached to their surface and two different types of surface-adsorbed Pt-complexes are an innovative solution for the design of functional bioactive materials. This material can be activated by exposure to either ultraviolet (UV) or visible (Vis) light. UV activation is allowed by the semiconductor HAp phase, while the activity induced by Vis light is related to complexes adsorbed onto the HAp surface. Pt metallic nanoparticles have the ability to trap electrons, which provides an extension of the material's activity during the period when it is kept in the dark.