of work: Sonodynamic therapy is a promising new modality for cancer treatment based on the synergistic effects of cell killing by a combination of sonosensitzer and ultrasound. Ultrasound can penetrate deeply into tissue and can be focused in a small region of tumor to activate non-toxic molecules (e.g. porphyrins ) thus minimizing undesirable side effects. The experimental evidence suggests that sonosensitization is due to the chemical activation of sonosensitizers inside or in close vicinity of hot collapsing cavitation bubbles to form sensitizer-derived radicals either by direct pyrolysis of the sensitizer at the water-gas interface or due to the reactions of hydrogen atoms and hydroxyl radicals formed by the pyrolysis of water. The free radicals derived from the sonosensitizer (mostly carbon-centered) react with oxygen to form peroxyl and alkoxyl radicals. Unlike OH radicals and H atoms which are formed by pyrolysis inside cavitation bubbles, the reactivity of alkoxyl and peroxyl radicals with organic compounds in biological media is much lower and hence they have a higher probability of reaching critical cellular sites. Recently we have succeeded in spin-trapping the carbon radicals formed during the sonolysis of aqueous solutions of various porphyrins .Umemura et al have proposed that the sonoluminescent light produced during cavitational collapse of microbubbles is responsible for the photoexcitation of the sensitizer, with subsequent formation of singlet oxygen, a known reactive cytotoxic species. We recently obtained further evidence against the singlet oxygen mechanism of Umemura by studying the sonolysis of aqueous oxygen-saturated solutions of Hematoporphyrin and Rose Bengal in 90% D2O using a sensitive new reagent which reacts specifically with singlet oxygen to produce an EPR detectable signal .Our results were inconsistent with a major role for singlet oxygen formation in the sonolysis of these compounds. The role of the hydrophobicity of sonosensitzers in determining their accumulation at the water - gas interface of ultrasound-induced cavitation bubbles is being studied by considering the Gibbs surface excess and the possible role of the dynamic surface tension using model surfactant molecules.Recent Publications:Misik,V., Miyoshi,N. and Riesz,P. Free Rad Biol Med 26:961-67, 1999.Misik,V. and Riesz,P. in """"""""Sonochemistry and Sonoluminescence""""""""ed.L.A.Crum et al. (eds.) NATO ASI Series,Kluwer Academic Publishers, 225-236, 1999Misik, V. and Riesz, P. Ann. New York Acad. Sci., 899:335-348, 2000.Miyoshi, N., Igarashi, T. and Riesz, P. Ultrasonics-Sonochemistry, 7:121-124, 2000.

National Institute of Health (NIH)
Division of Clinical Sciences - NCI (NCI)
Intramural Research (Z01)
Project #
Application #
Study Section
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Clinical Sciences
United States
Zip Code
Buldakov, Mikhail A; Hassan, Mariame A; Zhao, Qing-Li et al. (2009) Influence of changing pulse repetition frequency on chemical and biological effects induced by low-intensity ultrasound in vitro. Ultrason Sonochem 16:392-7
Sostaric, Joe Z (2008) A comparative sonochemical reaction that is independent of the intensity of ultrasound and the geometry of the exposure apparatus. Ultrason Sonochem 15:1043-8
Sostaric, Joe Z (2008) A chemical sensor that can detect the frequency of ultrasound. J Am Chem Soc 130:3248-9
Cheng, Jason Y; Riesz, Peter (2007) Mechanism of the protective effects of long chain n-alkyl glucopyranosides against ultrasound-induced cytolysis of HL-60 cells. Ultrason Sonochem 14:667-71
Sostaric, Joe Z; Miyoshi, Norio; Riesz, Peter et al. (2005) n-Alkyl glucopyranosides completely inhibit ultrasound-induced cytolysis. Free Radic Biol Med 39:1539-48
Feril Jr, Loreto B; Tsuda, Yuko; Kondo, Takashi et al. (2004) Ultrasound-induced killing of monocytic U937 cells enhanced by 2,2'-azobis(2-amidinopropane) dihydrochloride. Cancer Sci 95:181-5
Feril Jr, L B; Kondo, T; Takaya, K et al. (2004) Enhanced ultrasound-induced apoptosis and cell lysis by a hypotonic medium. Int J Radiat Biol 80:165-75
Rosenthal, Ionel; Sostaric, Joe Z; Riesz, Peter (2004) Sonodynamic therapy--a review of the synergistic effects of drugs and ultrasound. Ultrason Sonochem 11:349-63