Electrostatic Assembly of a Redox Catalysis System for Detection of Glutamate

Abstract

AbstractInterfacial assemblies capable of determining glutamate by redox catalysis are prepared by electrostatic assembly of alternating layers of ferrocene poly(allylamine) polymer and glutamate oxidase on a gold electrode. Deposition of the polymer was confirmed in cyclic voltammetry measurements by the presence of a surface wave corresponding to the oxidation of the ferrocene group. In the presence of glutamate in the adjacent electrolyte solution, the current increases and approaches a pseudosteady state, consistent with redox catalysis. Electrodes modified with glutamate oxidase had a linear response to glutamate up to 0.0045 M with sensitivity of 20 μA/cm2 and a limit of detection of 31.4 μM glutamate. An apparent Michaelis–Menten constant of 0.40(±0.13) mM for the confined glutamate oxidase was determined for this assembly. When used in flow‐injection experiments, glucose oxidase modified electrodes responded to transient zones of glucose; however, the detection limits of the assemblies to the flowing stream were substantially higher than found for measurements on static solutions.