TETRACYANOQUINODIMETHANE MEDIATED GLUCOSE SENSOR-BASED ON A SELF-ASSEMBLING ALKANETHIOL PHOSPHOLIPID BILAYER/

An amperometric tetracyanoquinodimethane (TCNQ) mediated biosensor far glucose is described, based on a self-assembling alkanethiol/phosphol ipid bilayer laid down onto a gold surface. Gold was sputter deposited onto chromium coated silicon wafers to a thickness of 200 nm. A monol ayer of alkanethiol was allowed to self-assemble from an ethanolic sol ution of dodecanethiol onto a freshly cleaned gold electrode in an ove rnight incubation. The monolayer was characterized by ellipsometric, i mpedance and cyclic voltammetry measurements (capacitance = 1.60 +/- 0 .06 mu F/cm(2), and thickness 1.34 +/- 0.15 nm). A mixture of phosphol ipid liposomes containing free amino groups was placed on the monolaye r and allowed to incubate overnight. The self-assembly of a phospholip id monolayer from the phospholipid solution onto the alkanethiol monol ayer, resulted in the formation of a bilayer. The formation of bilayer was again characterized by impedance and cyclic voltammetry measureme nts (capacitance = 0.98 +/- 0.09 mu F/cm(2), and thickness = 1.85 +/- 0.22 nm). TCNQ has been incorporated into the liposomes before the for mation of the bilayer. Glucose oxidase was cross-linked with the amino groups of the phospholipids using bis [2-(sulphosuccinimiidooxicarbony loxy) ethyl] sulphone. TCNQ which was incorporated in the bilayer acte d as an efficient mediator to regenerate glucose oxidase. Cyclic volta mmetry of the modified electrode and a response curve for the glucose sensor are reported.