Enzyme inhibition assays with an amperometric glucose biosensor based on athiolate self-assembled monolayer

A new bioelectrocatalytic enzyme membrane for biosensors based on immobiliz ation of glucose oxidase (GOx) is evaluated for use in inhibition assays. T he objectives are to show that the newly developed glucose biosensor has ad vantages for inhibition assays, not as a specific glucose biosensor as such . The mediator used is 2-aminoethanethiol, which forms a self-assembled mon olayer on the surface of a gold electrode. The membrane configuration consi sts of the thiol as mediator, covalently bound to the: gold electrode and a t the same time entrapped with GOx in a polyvinylpyridine (PVP) membrane. C yclic voltammetric scans indicate a catalytic peak at + 950 mV (vs. Ag/ AgC l) after addition of glucose to a blank phosphate buffer at pH 7.4. The PVP membranes are shown to be reusable for determination of glucose for at lea st one week. As an example of inhibition of the enzyme reaction, the respon se to glucose is shown to be sensitive to the addition of Hg(II) in the ppb range with a detection limit of 0.2 ppb. Interference to CV scans from oxi dizable organic compounds and other metal ions is found to be minimal, howe ver hydrogen peroxide is the exception and interferes at 1 mM concentration .