Highly sensitive and simultaneous detection of dopamine and uric acid at graphene nanoplatelet-modified fluorine-doped tin oxide electrode in the presence of ascorbic acid

We developed a graphene nanoplatelet-modified fluorine-doped tin oxide electrode (GNP/FTO) for the simultaneous detection of dopamine (DA) and uric acid (UA) in the presence of ascorbic acid (AA) and investigated the interaction mechanisms of DA, UA, and AA with GNPs considering their charging states at different pH values. Owing to the unique structure and properties originating from the oxygen and nitrogen functional groups at the edges, GNPs showed high electrocatalytic activity for the electrochemical oxidations of AA, DA, and UA with peak-to-peak potential separations (ΔEP) between AA-DA and DA-UA of ca. 0.23 and 0.17V, respectively. These values are sufficiently high to allow the simultaneous detection of DA and UA without interference from AA. The highly sensitive and stable GNP/FTO sensor showed sensitivities of ca. 0.15±0.004 and 0.14±0.007μA/μM, respectively, with detection limits of ca. 0.22±0.009 and 0.28±0.009μM, respectively, for DA and UA. The sensor could detect DA and UA concentrations in human serum samples with excellent recoveries. [Display omitted] •FTO was modified with graphene nanoplatelets (GNPs) by the e-spray method.•Dopamine and uric acid were simultaneously detected with GNP/FTO without interference from ascorbic acid.•Sensor allows low detection limits of 0.22 and 0.28μM for dopamine and uric acid, respectively.•Sensor shows good stability and recoveries from human serum samples.•The interaction mechanisms between dopamine, uric acid, and ascorbic acid with GNPs were discussed and verified.