Formation of an intact liposome layer adsorbed on oxidized gold confirmed by three complementary techniques: QCM-D, AFM and confocal fluorescence microscopy


B. Saramago, Centro de Química Estrutural, Complexo I, Instituto Superior Técnico, TU Lisbon, Av. Rovisco Pais, 1049–001 Lisboa, Portugal.



Supported layers of vesicles of dimyristoyl and dipalmitoyl phosphatidylcholine (DMPC and DPPC) containing cholesterol (CHOL) are adequate models for eukaryotic plasma membranes. Among the possible substrates to support these layers, gold offers the possibility of being used as an electrode for application in sensors. However, the formation of intact liposome layers on gold is not completely understood and several authors use more or less complex strategies to bind the liposomes. In this work we investigate the adsorption of unilamellar vesicles of DMPC, DMPC/CHOL and DMPC/DPPC/CHOL on the surface of oxidized gold using a quartz crystal microbalance with dissipation, atomic force microscopy and laser scanning confocal fluorescence microscopy. The results of all techniques indicate that for lipid concentrations ≥ 0.7 mg⋅mL–1 a dense layer of intact liposomes irreversibly adsorbs on the gold surface. Copyright © 2011 John Wiley & Sons, Ltd.