Graphene Oxide Wrapped SiO2 /TiO2 Hollow Nanoparticles Loaded with Photosensitizer for Photothermal and Photodynamic Combination Therapy.

Graphene oxide (GO) enwrapped SiO2 /TiO2 hollow nanoparticles (GO-HNP) are synthesized by the Stöber method and used as a nanocarrier for loading protoporphyrin IX (PpIX). The synthesized nanoparticle has high dispersibility and high uniformity in diameter (ca. 50 nm). Furthermore, this nanoparticle shows λ=808 nm laser induced PpIX release properties (photoinduced "on-off" drug-release system). GO-HNP-PpIX is employed for inducing both photothermal therapy (PTT) and photodynamic therapy (PDT). The synergic effect of PTT and PDT exhibits powerful anticancer properties. When cancer cells are treated with GO-HNP-PpIX and irradiated with both visible light and a NIR laser, the cell viability drops dramatically to 2.5 %, which is an anticancer effect approximately 13 times higher than that obtained in a previous study. Moreover, no significant cell damage has been observed under λ=808 nm laser irradiation. The GO-HNP-PpIX system suggests an external stimuli-responsive efficient anticancer treatment effect toward human breast cancer cells.