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Proceedings Paper

Evaluating the mechanical integrity of bilayer lipid membranes using a high-precision pressurization system
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Paper Abstract

A new methodology has been developed to measure the mechanical integrity of a bilayer lipid membrane (BLM) formed over porous substrates. A custom test fixture was fabricated in which a stepper motor linear actuator drives a piston in order to apply pressure to a BLM in very fine increments. The pressure, monitored with a pressure transducer, is observed to increase until the BLM reaches its failure pressure, and then drop. This experiment was performed on 1-Stearoyl-2-Oleoyl-sn-Glycero-3-Phosphocholine (SOPC) lipid bilayers formed over porous polycarbonate substrates with various pore sizes ranging from 0.05 - 10 &mgr;m in diameter. A trend of increasing failure pressure with decreasing pore size was observed. The same set of experiments was repeated for BLMs that were formed from a mixture of SOPC and cholesterol (CHOL) at a cholesterol concentration of 50 mol%. The presence of cholesterol was found to increase the failure pressure of the BLMs by 1.5 times on average. A model of the characteristic pressure curve from this experiment was developed based on an initially closed fluid system in which pressure increases as it is loaded by a moving piston, and which upon reaching a critical failure pressure allows pressure to decrease as fluid escapes through a porous medium. Since the BLM is formed over many pores, this model assumes that the failure pressure for each micro-BLM follows a normal distribution over all pores. The model is able to accurately predict the major trends in the pressurization curves by curve-fitting a few statistical parameters.

Paper Details

Date Published: 25 April 2007
PDF: 12 pages
Proc. SPIE 6526, Behavior and Mechanics of Multifunctional and Composite Materials 2007, 652611 (25 April 2007); doi: 10.1117/12.715643
Show Author Affiliations
David Hopkinson, Virginia Polytechnic Institute and State Univ. (United States)
Donald J. Leo, Virginia Polytechnic Institute and State Univ. (United States)

Published in SPIE Proceedings Vol. 6526:
Behavior and Mechanics of Multifunctional and Composite Materials 2007
Marcelo J. Dapino, Editor(s)

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