Anticancer Effects of Functionalized Carbon Nanotubes Combined with Ultrasound Irradiation through Reactive Oxygen Species Generation

The sonodynamically induced antitumor effect of functionalized carbon nanotubes (CNT) combined with ultrasound through reactive oxygen species generation was investigated. Both in vitro and in vivo antitumor effects were tested in combination with ultrasound at 2 MHz. The rate of ultrasonically induced damage on isolated sarcoma 180 cells was enhanced by twice with 80 mM CNT. This enhancement was significantly inhibited by histidine, which may suggest it was mediated by ultrasonically induced oxidation. The coadministraion of 25 mg/kg and ultrasonic exposure suppressed the growth of implanted colon 26 tomors at an intensity with which ultrasound alone showed only a slight antitumor effect. In addition, the combination of CNT and ultrasound substantially enhanced singlet oxygen generation. Sonodynamically induced cell damage and singlet oxygen generation were significantly suppressed by histidine and NaN3. These results indicate singlet oxygen plays an important role in sonodynamically induced antitumor effect. In conclusion, the presented results suggest that CNT is a potential sensitizer for sonodynamic tumor treatment.