Construction of protein-modified TiO2 nanoparticles for use with ultrasound irradiation in a novel cell injuring method.

Recently, our group discovered an alternative titanium dioxide (TiO(2)) activation method that uses ultrasound irradiation (US/TiO(2)) instead of ultraviolet irradiation. The pre-S1/S2 protein from hepatitis B virus, which recognizes liver cells, was immobilized to the surface of TiO(2) nanoparticles using an amino-coupling method. The ability of the protein-modified TiO(2) nanoparticles to recognize liver cells was confirmed by surface plasmon resonance analysis and immuno-staining analyses. After uptake of TiO(2) nanoparticles by HepG2 cancer cells, the cells were injured using this US/TiO(2) method; significant cell injury was observed at an ultrasound irradiation intensity of 0.4 W/cm(2). Together with these results, this strategy could be applied to new cell injuring systems that use ultrasound irradiation in place of photodynamic therapy in the near future. Copyright 2010 Elsevier Ltd. All rights reserved.