Microwave-Assisted Synthesis of Black Titanium Monoxide for Synergistic Tumor Phototherapy

Black titanium oxide has attracted tremendous interest in tumor phototherapy via converting light energy to heat and reactive oxygen species (ROS). Nevertheless, current synthesis methods suffer from inert gas shielding, high costs, complicated procedures, and expensive facilities, which are fairly impractical for treatment application. Herein, we propose a one-step strategy for fast facile synthesis of black TiO nanoparticles via a microwave-assisted hydrothermal synthesis approach with Ti power, hydrochloric acid, and hydrofluoric acid without the requirement of an reducing agent and high-temperature calcination. The prepared black TiO nanoparticles with an average size of 52 nm exhibit strong absorbance from ultraviolet (UV) to near-infrared light region, favoring a single agent and single light-induced synergistic phototherapy of tumors. The black TiO nanoparticles shows an excellent performance in phototherapy with a photothermal conversion efficiency up to 50% and a prominent ROS generation under 808 nm laser irradiation. The toxicity and therapeutic effect in vitro and in vivo are investigated, and the results elucidate that black TiO nanoparticles possess good biocompatibility and remarkable synergistic tumor therapeutic efficacy. The proposed microwave-assisted method opens up a novel way for the synthesis of titanium-based material in a simple and fast manner, promoting their applications in the biomedical field.