Visible Light Triggered Drug Release from TiO2 Nanotube Arrays: A Novel   Controllable Antibacterial Platform
  In this work, we use a double-layered stack of TiO2 nanotubes (TiNTs) to construct a visible-light triggered drug delivery system. Key for visible-light drug release is a hydrophobic cap on the nanotubes containing Au nanoparticles (AuNPs). The AuNPs allow for a photocatalytic scission of the hydrophobic chain under visible light. To demonstrate the principle, we loaded antibiotic (ampicillin sodium (AMP)) in the lower part of the TiO2 nanotube stack, triggered visible light induced release, and carried out antibacterial studies. The release from the platform becomes most controllable if the drug is silane-grafted in hydrophilic bottom layer for drug storage. Thus visible-light photocatalysis can also determine the release kinetics of the active drug from the nanotube wall. 
Jingwen Xu, Xuemei Zhou, Zhida Gao, Yan-Yan Song, Patrik Schmuki
physics.chem-ph cond-mat.mtrl-sci