Colored titanium oxides: From jewelry to biomedical applications

Titanium surface properties are related to the presence on the metal surface of a nanometric TiO2 film. It is possible to modify the TiO2 film by different techniques, among which the most effective is anodic oxidation. By modulating the operating conditions-electrolytic solution, cell voltage, and current density-it is possible to obtain films of increasing thicknesses and different crystalline structure which correspond to enhanced properties. In particular, it is possible to tune the surface color increasing the film thickness from few nanometers up to few hundreds of nanometers. The colored oxides thus obtained find applications ranging from the world of architecture and jewelry to the biomedical context. Anodic oxidation was exploited by Pietro Pedeferri as a powerful painting technique that permits to visualize the infinitely small and complex world where nanotechnologies operate and let anodizing become art.