Phosphatidylserine/cholesteral bilayers supported on a polycation/alkylthiol layer pair

1-Stearoyl-2-oleoyl phosphatidylserine (SOPS)/cholesterol bilayers, support ed on a polycation/alkylthiol layer pair on a gold surface, were investigat ed by surface plasmon resonance (SPR) and fluorescence recovery after photo bleaching. The substrate was formed by electrostatic adsorbance of a hydrat ed poly(diallyldimethylammonium chloride) (PDDA) layer on the negatively ch arged surface of a self-assembled monolayer of 11-mercaptoundecanoic acid ( MUA) on gold. Lipid membranes with different SOPS/cholesterol compositions were deposited on the PDDA/MUA layer pair by vesicle fusion. When the chole sterol content was below 20%, single bilayers were deposited. Fluorescence recovery after the bleaching experiments revealed that the SOPS/cholesterol bilayers were mobile at room temperature; lateral diffusion coefficients o f a fluorescence probe were approximately 1 x 10(-9) cm(2)/s. The kinetics of the addition of the ion-channel-forming peptide gramicidin to the suppor ted bilayers was detected by SPR. (C) 2000 Academic Press.