Solvothermal synthesis of Nb-doped TiO nanoparticles with enhanced sonodynamic effects for destroying tumors.

Titania (TiO) nanomaterials have been proved to be biocompatible sonosensitizers for sonodynamic therapy (SDT) of various cancer cells, while they suffer from weak sonodynamic effects due to fast combination of excited carriers. In this work, to improve the therapeutic efficiency, we prepared PEGylated Nb-doped TiO (TiO :Nb) nanoparticles by a simple solvothermal method and a subsequent surface modification process. The TiO :Nb nanoparticles exhibited an average size of 11 nm and a polydisperse index of 0.12. The Nb doping had no obvious effect on the phase of TiO matrixes but released electrons to the conduction band of TiO, resulting in high concentrations of deficiencies. As a result, the TiO :Nb nanoparticles exhibited a higher efficiency of singlet oxygen (O) generation than that of pure TiO nanoparticles upon ultrasound irradiation. Importantly, the TiO :Nb nanoparticles had high biocompatibility similar to pure TiO nanoparticles, while they could efficiently produce cytotoxic O to destroy cancer cells in comparison to the partially destroyed cancer cells by pure TiO nanoparticles upon ultrasound irradiation. More importantly, the TiO :Nb nanoparticles displayed obvious tumor cellular injury in tumor-bearing mice through high SDT effects. Therefore, the synthesized PEGylated TiO :Nb nanoparticles in this study exhibited higher therapeutic effects of SDT than that of the pure TiO nanoparticles, and the doping strategy would provide some insights for tuning traditional weak sonosensitizers into efficient ones.