Reactive argon-plasma activation of screen-printed carbon electrodes for highly selective dopamine determination

Dopamine (DA) deficiency has been linked to several psychiatric disorders. Electrochemical determination
of the level of DA suffers from abundant ascorbic acid (AA) and uric acid (UA) in body fluids. In this work,
a facile argon (Ar) plasma treatment was utilized to enhance the electrocatalytic reactivity of screenprinted
carbon electrodes (SPCEs) for selective DA detection. Surface characterization of the Ar-treated
SCPEs verified that the carbon paste binders were successfully removed and single-bonded oxygenated
moieties (–OH and C–O–C) were generated. Interestingly, the sharper D* and D′′ Raman interbands
were new key evidence of a higher exposure of carbon defect sites. Electrochemical studies further
revealed that the Ar-treated SPCEs possessed faster heterogeneous electron-transfer rates, larger
electroactive surface areas, and much higher conductivity when compared with untreated electrodes. As
a result, the oxidation potentials of AA, DA, and UA in the mixture could be well-resolved and the current
responses were significantly increased. The selective determination of DA in the presence of AA and UA
by differential pulse voltammetry gave two linear responses with the limit of detection of 0.27 mM (0.15–
10 mM range). Moreover, this Ar-treated SPCE had high reproducibility and good storage stability. These
results suggest that Ar-plasma treatment could be a promising method to enhance the electrocatalytic
properties of SPCEs for the detection of biomolecules.