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Please use this identifier to cite or link to this item: http://hdl.handle.net/1860/2520

Title: Ultrasound and model membrane interaction
Authors: Pong, Mona
Keywords: Chemical engineering;Ultrasound contrast media;Contrast-enhanced ultrasound--Equipment and supplies
Issue Date: 27-Dec-2007
Abstract: The fields of ultrasound bioeffects and membrane properties have been studied extensively in the past. However, the effects of membrane properties on ultrasound susceptibility have not been systematically studied. This work investigated the changes in membrane permeation (as indicated by fluorophore leakage) in vitro during exposure to ultrasound applied at center frequencies of 20 kHz, 1 MHz, and 1.55 MHz. Model membranes were used for the studies described here. Vesicles of various sizes, ranging from 100 nm to 1 μm, and various compositions were examined. The effect of incorporation of polyethylene glycol (PEG) into the bilayer membrane was studied using PEG concentrations ranging from 0-8 mol%. This work also gave the leakage profiles of samples containing cholesterol concentrations up to 65 mol%. In addition to PEG and cholesterol, the bilayer membranes were also composed of a combination of egg phosphatidylcholine, 1,2-Dioleoyl-sn-Glycero-3-Phosphocholine (DOPC), and 1,2-Dipalmitoyl-sn-Glycero-3-Phosphocholine (DPPC). Leakage was quantified in terms of temporal fluorescence intensity changes observed during carefully controlled ultrasound ON/OFF time intervals. In some experiments, the ON intervals were kept constant throughout. There were also experiments where the ON interval was allowed to vary. The OFF intervals were the same for all experiments. Results shown here demonstrated that while the ultrasound parameters were important in the ultrasound/membrane interaction, the properties of the membrane, as determined by composition and size, were equally as important. The major purpose of this work was to enhance the understanding of the interaction between ultrasound and cell membranes by studying the ultrasound parameters and membrane properties that govern this interaction. This work will prove to be helpful in diagnostic and therapeutic ultrasound applications.
URI: http://hdl.handle.net/1860/2520
Appears in Collections:Drexel Theses and Dissertations

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