A Sensitive and Selective Electrochemical Sensor Based on Graphene Quantum Dot/Gold Nanoparticle Nanocomposite Modified Electrode for the Determination of Quercetin in Biological Samples

A simple and sensitive electrochemical sensor based on (graphene quantum dot)/(gold nanoparticle) nanocomposite (GQD/AuNP) modified glassy carbon electrode (GCE) (GQD/AuNP/GCE) was constructed and utilized for the determination of quercetin. The nanocomposite of GQDs and AuNPs can greatly accelerate the electron transfer rate and showed excellent synergistic electrochemical activity for the oxidation of quercetin. Differential pulse voltammetry (DPV) was used for the quantitative determination of quercetin, the oxidation peak current was linear with the concentration of quercetin in the range of 0.01 to 6.0 μM with a detection limit of 2.0 nM which was more sensitive than most of the reported methods. Under the optimum conditions, the possible coexistence biological matrix including some metal ions, proteins, amino acids and other flavonoids with similar structures had no interference effect on the determination of quercetin. The proposed method was successfully applied to the sensitive determination of quercetin in human plasma samples with satisfactory recoveries.