Voltammetric determination of creatinine using a gold electrode modified with Nafion mixed with graphene quantum dots-copper

Abstract Creatinine levels in blood and urine can be used as an important biomarker for the diagnosis of renal, thyroid, and muscle malfunctions. In this work, a square-wave voltammetric method for creatinine was developed using a gold electrode modified with a film composed by Nafion mixed with a graphene quantum dots dispersion prepared in the presence of Cu2+. Such Au/Nafion-GQDs-Cu electrode relies on the interactions of creatinine with Cu2+ released from the oxidation of Cu thus decreasing the characteristic Cu/Cu2+ anodic peak at +350 mV. A linear response was obtained for the analyte in the concentration range from 1.0 × 10−6 mol L−1 (0.11 mg L−1) to 4.5 × 10−4 mol L−1 (50.9 mg L−1). The proposed sensor was simple to prepare and the method was successfully applied for creatinine determination in urine samples.