Ag@TiO2 Nanoprisms with Highly Efficient Near-Infrared Photothermal Conversion for Melanoma Therapy.

Melanoma is a primary reason of death from skin cancer and associated with high lethality. Photothermal therapy (PTT) has been developed into a powerful cancer treatment technique in recent years. Here, we created a low-cost and high-performance PTT agent, Ag@TiO2 NPs, which possesses a high photothermal conversion efficiency of ≈65 % and strong near-infrared (NIR) absorption about 808 nm. Ag NPs were synthesized using a two-step method and coated with TiO2 to obtain Ag@TiO2 NPs by a facile sol-gel method. Because of the oxide, Ag@TiO2 NPs exhibit remarkable high photothermal conversion efficiencies and biocompatibility in vivo and in vitro. Cytotoxicity and therapeutic efficiency of photothermal cytotoxicity of Ag@TiO2 NPs were tested in B16-F10 cells and C57BL/6J mice. Under light irradiation, the elevated temperature causes cell death in Ag NPs-treated (100 µg mL-1 ) cells in vitro (both p<0.01). In the case of subcutaneous melanoma tumor model, Ag@TiO2 NPs (100 µg mL-1 ) were injected into the tumor and irradiated with a 808 nm laser of 2 W cm-2 for 1 minute. As a consequence, the tumor volume gradually decreased by NIR laser irradiation with only a single treatment. The results demonstrate that Ag@TiO2 NPs are biocompatible and an attractive photothermal agent for cutaneous melanoma by local delivery.