Ultrasound activation of TiO2 in melanoma tumors.

Sonodynamic therapy (SDT) is a new modality using ultrasound (US) to activate certain chemical sensitizers for cancer therapy. In this study, the effect of US combined with a nanoparticle titanium dioxide (TiO(2)) on melanoma cell was investigated in vitro and in vivo. Melanoma cells (C32) were irradiated with US in the presence and/or absence of TiO(2). Cell viability was measured immediately after US irradiation (1MHz, 0.5 and 1.0W/cm(2) for 10s). The effect of the combination of TiO(2) and US exposure (1MHz, 1.0W/cm(2), 2 min duration) on subcutaneously implanted C32 solid tumors in mice were investigated by measuring tumor volume regression. The cell viability was significantly decreased only after US irradiation in the presence of TiO(2). In vivo results showed significant inhibition of tumor growth in groups treated with TiO(2) and US. To our knowledge, this is the first report to demonstrate the cell killing effect of TiO(2) nanoparticles under the irradiation US in vitro and in vivo. Copyright © 2010 Elsevier B.V. All rights reserved.