Free-standing Plastic electrodes: Formulation, electrochemical characterization and application to dopamine detection

Abstract The interest in the optimization of new materials for electrodes preparation increased in recent years. The present paper reports about the optimization of composite free standing graphite-based plastic electrodes. The simple and cheap procedure of preparation, associated to the mechanical features i.e. flexibility and to the aptitude to be custom shape, makes this plastic conductive material appealing for sensors and biosensors development. This paper reports about the formulation studies performed to obtain the flexible plastic-electrodes graphite-based (PE) and about their bulk-modification assayed to obtain selectivity and to enlarge the PEs field of application. Plastic-electrodes were electrochemically characterized by cyclic voltammetry in presence of potassium ferrocyanide as benchmark redox system. The performances of plastic electrodes were investigated to measure by amperometry dopamine (DA), in presence of ascorbic acid (AA) and uric acid (UA) which in biological system usually interfere for an accurate DA detection. The optimized plastic electrodes were able to detect selectively dopamine in presence of a mixed solution of AA and UA, with a linear range from 10 μM to 0.5 mM and a lower detection limit of 3 μM (LOD = 3 σ blank ). The selective detection was obtained by bulk-modification of plastisol used for plastic electrodes preparation. Preliminary recovery tests were performed in urine as biological sample. The demonstration that this procedure of bulk-modification is achievable enlarges the field of applications and expands the applications versatility of the proposed PE's.