title: Photocurrents generated by bacteriorhodopsin adsorbed on nano-black lipid membranes.
abstract: Purple membranes were adsorbed on freestanding lipid bilayers, termed nano-black lipid membranes (nano-BLMs), suspending the pores of porous alumina substrates with average pore diameters of 280 nm. Nano-BLMs were obtained by first coating the upper surface of the highly ordered porous alumina substrates with a thin gold layer followed by chemisorption of 1,2-dipalmitoyl-sn-glycero-3-phosphothioethanol and subsequent addition of a droplet of 1,2-diphytanoyl-sn-glycero-3-phosphocholine and octadecylamine dissolved in n-decane onto the hydrophobic submonolayer. By means of impedance spectroscopy, the quality of the nano-BLMs was verified. The electrical parameters confirm the formation of single lipid bilayers with high membrane resistances covering the porous matrix. Adsorption of purple membranes on the nano-BLMs was followed by recording the photocurrents generated by bacteriorhodopsin upon continuous light illumination. The membrane system exhibits a very high long-term stability with the advantage that not only transient but also stationary currents are recordable. By adding the proton ionophore carbonyl cyanide-m-chlorophenylhydrazone the conductivity of the nano-BLMs increases, resulting in a higher stationary current, which proves that proton conductance occurs across the nano-BLMs.
authors.affiliation: Institut für Analytische Chemie, Chemo- und Biosensorik, Universität Regensburg, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Horn
authors.forename: Claudia
authors.initials: C
authors.lastname: Steinem
mesh_terms: D000327:Adsorption; D001436:Bacteriorhodopsins / Q000737:chemistry* / Q000528:radiation effects*; D040761:Biomimetic Materials / Q000737:chemistry*; D004307:Dose-Response Relationship, Radiation; D008027:Light; D008051:Lipid Bilayers / Q000737:chemistry*; D008564:Membrane Potentials / Q000528:radiation effects*; D008567:Membranes, Artificial; D049329:Nanostructures / Q000737:chemistry*; D010777:Photochemistry / Q000295:instrumentation / Q000379:methods*; D011485:Protein Binding; D018717:Purple Membrane / Q000737:chemistry / Q000528:radiation effects; D011829:Radiation Dosage
chemical_list: D008051:Lipid Bilayers; D008567:Membranes, Artificial; D001436:Bacteriorhodopsins