The physical stresses biological cells are exposed to due to micro-streaming caused by the cavitations of ultrasound activated micro-bubbles
here have been several studies into the possible use applications of medicinal ultrasound. These include such uses as the dissolution of blood clots, a therapeutic instrument to fight cancer, and the breaking up of kidney stones. Not surprisingly there have also been several investigations into the effect that high intensity focused ultrasound (HIFU) has a biological cells. While these studies have shown that exposure to ultrasound can cause cell lysis, and increased porosity they have only provided limited investigation into the mechanism through which these effects occur.
Stable cavitation can generate high velocity fluid flow at the air water interface of the gas body, resulting in shear forces that can damage biological material. It is hypothesized that such a force can damage the cell membrane causing an increased inward or outward flow of molecules across the membrane. It is also recognized that this damage is reversible, meaning that the membrane can be repaired. If this is true, this technology can be used to increase the success rate of various drug delivery treatments.
Our experiment will examine the physical stresses biological cells are exposed to due to micro-streaming caused by the cavitations of ultrasound activated micro-bubbles. A water filled tank containing a chamber, with the biological cells pasted onto both sides of a nucleopore membrane, used to ensure stable cavitation, and an unfocused transducer, aimed at the membrane, are used to conduct the experiments. The cells will be tested under several conditions. In one test to examine to the mechanical stress caused by micro-streaming simple red blood cells will be used. The percentage of cells in which cell lysis occurs will be calculated. In the tests to examine increased porosity the percentage of cells absorbing a phosphorescent molecule under different conditions will be calculated. We expect porosity as well as the percentage of cell lysis to both increase in tests that micro-streaming is taking place.
