title: Enhanced OH radical generation by dual-frequency ultrasound with TiO2 nanoparticles: its application to targeted sonodynamic therapy.
abstract: The present study demonstrated the enhanced hydroxyl (OH) radical generation by combined use of dual-frequency (0.5 MHz and 1 MHz) ultrasound (US) and titanium dioxide (TiO2) nanoparticles (NPs) as sonocatalyst. The OH radical generation became the maximum, when 0.5 MHz US was irradiated at an intensity of 0.8 W/cm(2) and 1 MHz US was irradiated at intensities at 0.4 W/cm(2) in the presence of TiO2 NPs under the examined conditions. After incorporation of TiO2 NPs modified with targeting protein pre-S1/S2, HepG2 cancer cells were subjected to the dual-frequency US at optimum irradiation intensities ("targeted-TiO2/dual-US treatment"). Growth of the HepG2 cells was reduced by 46% compared with the control condition after irradiation of dual-frequency US for 60s with TiO2 NPs incorporation. In contrast, HepG2 cell growth was almost the same as that in the control condition when cells were irradiated with either 0.5 MHz or 1 MHz ultrasound alone without TiO2 NP incorporation.
authors.affiliation: Institute of Nature and Environmental Technology, Kanazawa University, Kanazawa 920-1192, Japan.
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Ninomiya
authors.forename: Kyohei
authors.initials: K
authors.lastname: Noda
authors.forename: Chiaki
authors.initials: C
authors.lastname: Ogino
authors.forename: Shun-ichi
authors.initials: S
authors.lastname: Kuroda
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Shimizu
mesh_terms: D049109:Cell Proliferation; D056945:Hep G2 Cells; D006801:Humans; D017665:Hydroxyl Radical / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D014025:Titanium / Q000737:chemistry*; D014464:Ultrasonic Therapy; D014465:Ultrasonics
chemical_list: C009495:titanium dioxide; D017665:Hydroxyl Radical; D014025:Titanium
keywords: Dual-frequency; Hydroxyl radical; Nanoparticles; Sonodynamic therapy; Titanium dioxide; Ultrasound