Studying the interactions of drugs and hydrophobic model membranes using contact angle goniometry

This study demonstrates a method where contact angle goniometry combined with surface tension measurements is used to assess the interactions of drugs with the hydrophobic core of a biological membrane. To this end, self-assembled monolayers (SAMs) of two alkanethiol and one thiolipid on Au(111) surfaces are used as model membranes and their interaction with six beta-blockers is studied. The Gibbs equation and the Langmuir adsorption isotherm are used to determine the partition coefficients for the adsorption of the drugs, which are compared to the octanol-water partition coefficients as well as the liposome-water partition coefficients. The ability of the different SAMs to serve as model membranes in partitioning of drugs is discussed. (C) 2009 Elsevier B.V. All rights reserved.