Structure of anionic phospholipid coatings on silica by dissipative quartz crystal microbalance.
ABSTRACT The adsorption of anionic phospholipids on silica was investigated by the dissipative quartz crystal microbalance (QCM) technique. Liposomes composed of 1 mM 80:20 mol % of 1-palmitoyl-2-oleyl-sn-glycero-3-phosphatidylcholine (POPC)/phosphatidic acid, POPC/phosphatidylglycerol, or POPC/phosphatidylserine in N-(2-hydroxyethyl)piperazine-N'-(2-ethanesulfonic acid) buffer at pH 7.4 (with or without 3 mM of CaCl2) were examined. We have previously demonstrated that similar phospholipid coatings can be used in capillary electrochromatography as a stationary phase for the separation of analytes. In this work, we focus on the formation of the coatings and on the type of lipid structure formed on silica. The QCM investigation comprised qualitative results based on changes in frequency and resistance, and quantitative modeling of the obtained results. The latter was performed using the dissipative QCM, which measures the quartz crystal impedance, combined with equivalent circuit analysis. A previously developed coating and cleaning procedure for phospholipid-coated fused silica capillaries was adopted in this study, and the same silica-coated crystal was used throughout the QCM study. We will demonstrate in this work that the type of lipid structure formed on silica, that is, a rather rigid supported lipid bilayer or a viscoelastic supported vesicle layer (SVL), is highly dependent on the lipid and solvent composition. We also show for the first time that the modeling of the dissipative QCM data can be used to extract a more quantitative picture of an adsorbed SVL, because, so far, published studies have merely used the QCM data in a qualitative sense.
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ABSTRACT: Since the publication of the original review of piezoelectric acoustic sensors in this series there has been a consistent, gradual expansion in the number of published papers using 'quartz crystal microbalances' (QCM). Between 2001 and 2009, the number of QCM publications per annum has increased from 49 to 273, with a two-fold increase in papers per annum between 2004 and 2008. Within the field, comparing the time covered by the current to the previous review, there are trends towards increasing use of QCM in the study of protein adsorption to surfaces (93% increase), homeostasis (67% increase), protein-protein interactions (40% increase) and carbohydrates (43% increase). New commercial systems have been released that are driving the uptake of the technology for characterization of binding specificities, affinities, kinetics and conformational changes associated with a molecular recognition event. This paper highlights theoretical and practical aspects of the principles that underpin acoustic analysis, then reviews exemplary papers in key application areas involving small molecular weight ligands, carbohydrates, proteins, nucleic acids, viruses, bacteria, cells and membrane interfaces.Journal of Molecular Recognition 08/2011; 24(5):754-87. · 3.01 Impact Factor
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ABSTRACT: Supported layers of vesicles of dimyristoyl and dipalmitoyl phosphatidylcholine containing cholesterol are adequate models for eukaryotic plasma membranes. In this work it was investigated the adsorption of unilamellar vesicles on the surface of oxidized gold, using a QCM-D, AFM and LSCFM. The results of all techniques indicate that a dense layer of intact liposomes irreversibly adsorbs on the gold surface. It was also investigated the interaction of some examples of local and general anaesthetics with these membrane models, using a QCM-D. Lidocaine, tetracaine, ropivacaine and levobupivacaine were chosen as local anaesthetics examples, and propofol as general anaesthetic. Simultaneously, the interaction of the anaesthetics with the same liposomes in suspension was studied, using DSC.01/2011;
- Journal of The American College of Cardiology - J AMER COLL CARDIOL. 01/2011; 57(14).