Use of polymer films in amperometric biosensors and chemically modified electrodes

Quinone-amine polymeric films were used in the construction of glucose biosensors from platinum microelectrodes (500 {dollar}mu{dollar}m diameter). A poly(1,3-diaminobenzene) (DAB) film was used in the preparation of an amperometric sensor based upon a cyclodextrin-modified spectroscopic grade graphite electrode (8 mm diameter). The focus of this work was to construct sensors of enhanced selectivity through the use of polymeric films. Additional selectivity was imparted using glucose oxidase for the glucose biosensors and cyclodextrin for the chemically modified electrodes. In the case of the glucose biosensors, the film imparted selectivity by preventing potential interferences from reaching the electrode surface. For the cyclodextrin/poly(1,3-DAB)-modified electrodes, the polymeric film functioned as a diffusional barrier preventing direct access of analyte (or potentially interfering substances) to the electrode surface. The film allowed access to the electrode surface only through the cavity of the cyclodextrin.; The preparation of the glucose biosensors involved adapting a conventional organic synthesis of quinone-amine polymer to permit application of this polymer as a film onto a platinum electrode using cyclic voltammetry. The formation of a quinone-amine film on the surface of a platinum electrode was demonstrated in an aqueous sodium fluoride system using cyclic voltammetry. Other systems and procedures for film formation were considered in order to develop a film of enhanced permeability to hydrogen peroxide that would selectively block the interferences. Films exhibiting the best permselectivity and ruggedness were prepared using systems that consisted of potassium bromide in sodium nitrate and sodium nitrate (without potassium bromide). The application of glucose oxidase using glutaraldehyde for crosslinking to produce a biosensor suitable for the determination of glucose concentration was the final phase of the quinone-amine work.; Wax impregnated spectroscopic grade graphite electrodes were prepared. Cyclodextrin was adsorbed onto the surface of the wax impregnated graphite electrodes and, subsequently, 1,3-DAB was electropolymerized onto the surface of the electrode. The resolution of structural isomers was demonstrated.