Joe Z. Sostaric

Correlation between sonochemistry of surfactant solutions and human leukemia cell killing by ultrasound and porphyrins

The synergistic effect of ultrasound and drugs on cells is known as sonodynamic therapy. The use of sonodynamic therapy for the potential clinical treatment of certain tumors is promising, however, the mechanism of sonodynamic therapy could be due to either sonomechanical and/or sonochemical effects on the cells. The aim of the current study is to determine the importance of the sonochemical mechanism for sonodynamic therapy. Sonochemical effects arise from the formation of radical species following collapse of cavitation bubbles. The synergistic effect of ultrasound (47 kHz) and analogues of a gallium-porphyrin derivative (ATX-70) on cytolysis of Human leukemia cells (HL-525 and HL-60) suspended in a cell culture medium were studied. Organic surfactants preferentially accumulate and subsequently decompose at the gas/solution interface of cavitation bubbles, producing secondary radicals that can diffuse to the bulk solution. The gallium porphyrin analogues used in the current study possess two n-alkyl side chains (ATX-C(x), where x = number of carbon atoms, ranging from x = 2 to x = 12). By varying the n-alkyl chain length, thereby modifying the surfactant properties of the ATX-C(x) derivatives, cell killing in relation to the accumulation of ATX-C(x) derivatives at the gas/solution interface of cavitation bubbles was determined. Following sonolysis in the presence of ATX-C(x), a strong correlation for the yield of carbon-centered radicals and cell killing was observed. These results support the hypothesis that a sonochemical mechanism is responsible for the synergistic effect of ultrasound and ATX-C(x) on HL-525 and HL-60 cells.

A chemical sensor that can detect the frequency of ultrasound.

Herein is described a chemical sensor that can detect the frequency of ultrasound. Exposure of aqueous n-alkyl sulfate or sulfonate surfactant solutions to high-intensity ultrasound results in the formation of secondary carbon-centered radicals. The yield of these radicals reaches a maximum plateau, the magnitude of which is limited by the dynamic ability of the surfactant to accumulate at the rapidly oscillating gas/solution interface of cavitation bubbles. For this reason, the maximum plateau yield observed following sonolysis of sodium butane sulfonate solutions compared to that of sodium dodecyl sulfate solutions (i.e., CHSBSo/CHSDS) was greater than 1. Interestingly, it was found that the CHSBSo/CHSDS ratio had a linear dependence on ultrasound frequency. Since it is known from earlier studies that the CHSBSo/CHSDS ratio is independent of ultrasound intensity and of the geometry of flat plate exposure systems, a plot of the CHSBSo/CHSDS ratio against ultrasound frequency yields a calibration curve. W...

Complete Inhibition Of Ultrasound Induced Cytolysis In The Presence Of Inertial Cavitation

The investigation of ultrasound for biotechnological applications including non‐invasive surgery (HIFU), drug/gene delivery to cells (sonoporation) or through the skin (sonophoresis) and ultrasound assisted bioreactors has focused mainly on the physical effects of ultrasound. The beneficial effects of ultrasound rely on a number of application‐dependent mechanisms, and may include tissue heating, acoustic streaming or cavitation. Although acoustic cavitation is necessary in some systems, cavitation bubbles simultaneously result in uncontrollable cell damage and cytolysis. Thus, the development of a number of biotechnological uses of ultrasound has been hampered by the necessity to constrain exposure parameters in order to prevent the occurrence of acoustic cavitation or to at least limit the detrimental effects of cavitation. The current study shows that non‐toxic concentrations of specific n‐alkyl solutes completely inhibit ultrasound induced cytolysis of in vitro suspensions of human leukemia cells (HL‐...

Correlation between sonochemistry of surfactant solutions and human leukaemia cell killing by ultrasound and porphyrins

The synergistic effect of ultrasound and drugs on cells is known as sonodynamic therapy and has been shown to be effective in killing cancer cells in vitro and in tumor bearing animals.