Tethered bilayer lipid membranes self-assembled on mercury electrodes.
In order to incorporate integral proteins in a functionally active state, metal-supported lipid bilayers must have a hydrophilic region interposed between the bilayer and the metal. This region is realized with a hydrophilic molecule terminating at one end with a sulfhydryl or disulfide group that anchors this "hydrophilic spacer" to the surface of a metal, such as gold or mercury. The other end of the hydrophilic spacer may be covalently linked to the polar head of a phospholipid molecule, giving rise to a supramolecule called "thiolipid" (TL). With respect to gold, mercury has the advantage of providing a defect-free and fluid surface to the self-assembling spacer. Hydrophilic spacers consisting of a polyethyleneoxy or a hexapeptide chain, as well as thiolipids derived from these spacers, were employed to fabricate mercury-supported lipid bilayers. The formation of a lipid bilayer on top of a self-assembled monolayer of a hydrophilic spacer, or of a single-lipid monolayer on top of a self-assembled monolayer of a thiolipid, was realized by simply immersing the coated mercury electrode into an aqueous solution across a lipid film previously spread on its surface at its spreading pressure. Particularly stable mercury-supported lipid bilayers were obtained by using thiolipids. The biomimetic properties of these lipid bilayers were tested by incorporating channel-forming polypeptides (gramicidin and melittin) and proteins (OmpF porin). The effect of the transmembrane potential on the function of these channels was estimated by using a simple electrostatic model of the mercury-solution interphase.
Moncelli
M R
MR
Chemistry Department, Laboratory of Bioelectrochemistry, University of Florence, Via della Lastruccia 3, 50019 Sesto Fiorentino Florence, Italy. moncelli@unifi.it
Becucci
L
L
Schiller
S M
SM
D040761:Biomimetic Materials / Q000737:chemistry; D020099:Coated Materials, Biocompatible / Q000737:chemistry*; D003460:Crystallization / Q000379:methods*; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D015640:Ion Channel Gating; D007473:Ion Channels / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D008564:Membrane Potentials; D008567:Membranes, Artificial; D008628:Mercury / Q000737:chemistry*
D020099:Coated Materials, Biocompatible; D007473:Ion Channels; D008051:Lipid Bilayers; D008567:Membranes, Artificial; D008628:Mercury