ABSTRACT
Hydrogels of poly(acrylamide) and poly(ethylene oxide) are convenient and biocompatible media for use as physically rigid, solid state voltammetry solvents. Thin gel slices containing supporting electrolyte, buffer components and other reagents can be laid atop in-plane patterns of working, reference and auxiliary electrodes, dried in place and then reswelled with microdroplets containing electroactive species, enzyme substrates, or haptens to observe, respectively, conventional electrochemical voltammetry of the electroactive probe, electrocatalytic currents resulting from electron-transfer mediated turnover of an enzyme in the presence of the added substrate, or enhanced electrocatalytic currents resulting from displacement of redox-labelled hapten from an antibody by the added hapten. Examples of such reactions in hydrogels are given, including the mediated oxidation of sulfite by sulfite oxidase, of glucose by glucose oxidase, and enzyme-enhanced immunoassay of phenytoin. The hydrogel films are potentially useful packaging strategies for electrochemical assays employing microlithographically-defined, disposable electrochemical microcells.
