Abstract
A gold electrode modified with a polypyrrole–mesoporous silica molecular sieves (polypyrrole—MCM-48) nanostructure film was used for the electrochemical determination of small concentrations of dopamine (DA) by cyclic voltammetry and square-wave voltammetry techniques. This electrode showed good electrocatalytic activity for the oxidation of dopamine. The oxidation potential of dopamine was decreased significantly compared with that obtained at the bare gold electrode. The observed linear range for the determination of the dopamine concentration, without interferents through cyclic voltammetry measurements, was from 10 μM to 1.2 mM (R2 = 0.9989) for the gold electrode modified with the polypyrrole—MCM-48 nanostructure, with a detection limit of 2.5 μM. In the case of square-wave voltammetry, the linear range was 2–250 μM, with a correlation coefficient of 0.9996, and the detection limit was estimated to be 0.7 μM. The effects of interferents, such as ascorbic acid (AA) and uric acid (UA), on the electrochemical detection of dopamine were also examined. The modified electrode can successfully separate the oxidation potentials for ascorbic acid and dopamine, shifting the oxidation peak potential of ascorbic acid to a more positive potential, and significantly decreasing the peak current. The presence of ascorbic acid increased the sensitivity of dopamine determination at the modified electrode, and the detection limit was estimated to be 0.5 μM with 0.1 mM ascorbic acid to imitate physiological solutions. Additionally, studies showed that the presence of uric acid does not affect the electrochemical detection of dopamine. The modified electrode can be successfully applied for the quantitative analysis of dopamine both with and without interferents.
Highlights
Dopamine is one of the most important neurotransmitters in the central nervous, renal, and hormonal systems, as well as in drug addiction and Parkinson’s disease [1,2]
We report the electrochemical behavior of dopamine at the surface of a polypyrrole—MCM-48 nanostructure-modified Au electrode, both in the presence and absence of ascorbic acid and/or uric acid
The polypyrrole—MCM-48 nanocomposite powder was dispersed by sonication in dichloromethane solution to form a homogenous mixture
Summary
Dopamine is one of the most important neurotransmitters in the central nervous, renal, and hormonal systems, as well as in drug addiction and Parkinson’s disease [1,2]. Oshaka and co-workers studied the voltammetric behavior of dopamine in the presence of ascorbic acid at an electropolymerized film of N,N-dimethylaniline, coated on a glassy carbon electrode [7]. This electrode showed a stable response without fouling of the electrode surface by the adsorption of the oxidized product of ascorbic acid. Ramanavicius and co-workers reported that modification of glassy carbon electrodes with copper nanoparticlesallows for dopamine determination in the presence of ascorbic acid, uric acid, and p-acetamidophenol [13]. We discuss the suitability of these modified electrodes in the voltammetric determination of dopamine in a phosphate buffer solution
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