Simultaneous Detection of Dopamine and Oxygen Species Using Coated Electrodes

The various coatings were used for simultaneous determination of dopamine and oxygen species for biological application. The conditioning waveform at bare electrode was found to give more reproducible Oxygen Reduction Reaction (ORR) amperometric response than those coatings (without condition waveform).

This work provides some examples of how the variation of surface composition can alter the electrocatalytic properties of Pt and Carbon Fiber (CF) electrodes towards the ORR and dopamine oxidation. Various types of modifications show advantages and limitation in measuring the redox species under study.

Based on these preliminary investigations, coated Pt electrode in most cases is better as a catalyst for detecting dopamine and oxygen. However, this noble metal is well known for instability for practical use in vivo. Employing Differential Pulse Voltammetry (DPV) technique, the detection of dopamine was not superior in enhancing dopamine signal, although its capability in the discrimination of the background effect and the presence of coating.

The data obtained also showed the better reproducibility of the response for the electroreduction of oxygen when applying the conditioning waveform at the bare electrode rather than use of coatings (without any conditioning waveform) at the Pt electrode. Polypyrrole and poly(phyenlene) coatings are the best two coatings for the oxidation of  dopamine species and to obtain a reproducible surface for the amperometric response of oxygen.

Electrodes covalently modified with substituted diazonium salts can be used for further chemical modification. This in turn suggests the ability to tune the property of the modified electrode to be used for many applications like dopamine and other neurotransmitter determinations.

Voltammetric investigations in biological media encounter the problem of interferences. Adsorption of protein molecules is another difficulty in the measurement. For the tried coatings the electrochemically modified electrodes can be used then to test the ability to prevent protein adsorption at the electrode.  The stability of the electrode is another issue which needs to be taken into account and the trials for prolonging the use of the coated electrodes are some targets that need to be achieved in further work.