Vijoleta Lucija Bronislava Braach-Maksvytis

AMBRI biosensor: stabilizing artificial membranes and receptor attachment

The AMBRI Ion Channel Switch biosensor is a novel scanning technology with broad application in a variety of fields. The technology is based on an artificial bilayer membrane attached to gold through hydrophilic tethers. The lamellar bilayer membrane possesses electrical characteristics similar to black (bilayer) lipid membranes being sealed with a capacitance of approximately 0.6 (mu) F/cm2, is fluid, and is stable to a variety of media including plasma and whole blood and to challenges with solvent solutions. Receptors/antibodies can be attached to the membrane through biotin-streptavidin linkages, and use of caged biotin species allows optical patterning of the membrane surface.

Gated ion channel biosensor: a functioning nanomachine

Biosensors combine a biological recognition mechanisms with a physical transduction technique. In nature, the transduction mechanism for high sensitivity molecular detection is modulation of cell membrane ionic conductivity, through specific ligand - receptor binding induced switching of ion channels. This effects an inherent signal amplification of 6-8 orders of magnitude, corresponding to the total ion flow arising from the single channel gating event. Here we describe the first reduction of this principle to a practical sensing device, which is a planar impedance element composed of a macroscopically supported synthetic bilayer membrane incorporating ion channels. The membrane and ionic reservoir are covalently attached to an evaporated gold surface. The channels have specific receptor groups attached which permit switching of the channels by analyte binding to the receptors. The device may then be made specific for the detection of a very wide range of analytes, including proteins, drugs, hormones, antibodies, DNA, etc., currently in the 10-7-10-12 M range. It also lends itself readily to microelectronic fabrication, the optimum sensitivity range of the device may be tuned over several orders of magnitude.