Ultrasensitive Determination of Dopamine and Uric Acid Based on Gold Nanoparticles@Carbon Dots/Electrochemical Reduced Graphene Oxide modified glassy carbon electrode

An ultrasensitive electrochemical sensing platform based on a glassy carbon electrode (GCE) modified with electrochemically reduced graphene oxide (erGO) and gold nanoparticles@carbon dots (GNPs@CDs) was developed. The hydroxyl-rich CDs were electrochemically synthesized, and the GNPs@CDs were obtained by reducing chloroauric acid with hydroxyl-rich CDs. The electrochemical behavior of the fabricated electrode, GNPs@CDs/erGO/GCE, was explored by cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical performance of the electrode demonstrated a remarkable enhancement in the peak current toward oxidation of dopamine (DA) and uric acid (UA) with a peak potential separation of 0.15 V in the presence of ascorbic acid (AA). Under optimized conditions, the simultaneous determination of DA and UA was investigated using differential pulse voltammetry (DPV) resulting in a linear response in the concentration ranges of 0.01−5.0 μM and 5.0−20.0 μM for DA and of 0.1−20.0 μM and 20.0−50.0 μM for UA and in a sensitivity of 11.96 and 6.48 μA μM -1 , respectively. The prepared electrode also demonstrated long-term stability and good reproducibility and was successfully used for the determination of DA and UA in human serum samples with favorable recoveries.