Au Nanoclusters Sensitized Black TiO Nanotubes for Enhanced Photodynamic Therapy Driven by Near-Infrared Light.

The low reactive oxygen species production capability and the shallow tissue penetration of excited light (UV) are still two barriers in photodynamic therapy (PDT). Here, Au cluster anchored black anatase TiO nanotubes (abbreviated as Au /B-TiO NTs) are synthesized by gaseous reduction of anatase TiO NTs and subsequent deposition of noble metal. The Au /B-TiO NTs with thickness of about 2 nm exhibit excellent PDT performance. The reduction process increased the density of Ti on the surface of TiO , which effectively depresses the recombination of electron and hole. Furthermore, after modification of Au nanoclusters, the PDT efficiency is further enhanced owing to the changed electrical distribution in the composite, which forms a shallow potential well on the metal-TiO interface to further hamper the recombination of electron and hole. Especially, the reduction of anatase TiO can expend the light response range (UV) of TiO to the visible and even near infrared (NIR) light region with high tissue penetration depth. When excited by NIR light, the nanoplatform shows markedly improved therapeutic efficacy attributed to the photocatalytic synergistic effect, and promotes separation or restrained recombination of electron and hole, which is verified by experimental results in vitro and in vivo.