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An effective nanocomposite sensor for selective electroanalytical dopamine (DA) determination using overoxidized conducting polymer of poly‐1,5‐diaminonaphthalene (OPoly‐1,5‐DAN) functionalized graphene nanosheets (GNS) was achieved. The OPoly‐1,5‐DAN/GNS nanocomposite polymer was prepared via an electropolymerization of 1,5‐DAN on GNS/GCE after 7 cycles of potential scan (−0.2 V to +0.9 V), followed by an electrooveroxidation of the nanocomposite Poly‐1,5‐DAN/GNS by the potential cycle (0.0 V to +1.8 V) for 2 scans. The OPoly‐1,5‐DAN was effectively designed by GNS as a uniformly distribution of nanocomposite that caused more accumulations of analyte due to large electrocatalytic active positions created on electrode surface. The high specific and sensitive performance of the OPoly‐1,5‐DAN/GNS nanocomposite polymer was conducted to greater effective electrons transferring behavior for DA with copresent of vitamin C (VC). The stable and suitable formation of OPoly‐1,5‐DAN/GNS nanocomposite polymer showed rapid charge transport voltammogram and obvious electrocatalytic activity to DA and eliminated VC response. Moreover, the OPoly‐1,5‐DAN/GNS displays an excellent responses to DA determination with wide linear range (LR) 1.0–150 μM and lower detection limit (DL) 8.82±0.1 nM as comparing with other studies. Additionally, the excellent reproducibility of OPoly‐1,5‐DAN/GNS as well as long‐term stability indicated that it is an excellent and effective electrochemical DA sensor. Finally, the electroanalytical application of the OPoly‐1,5‐DAN/GNS nanocomposite polymer was employed for the electroanalysis of DA in human urine. [ABSTRACT FROM AUTHOR]

A new nanocomposite based on ruthenium nanoparticles (RuNPs) uniformly designed at chemically treated graphene oxide nanosheets (CTGONS) was prepared as active electrode for simultaneously sensing of dopamine (DA) and acetaminophen (AC) in the presence of high concentration of ascorbic acid (AA). The RuNPs actively decorates the CTGONS with uniform dispersion like pump sputtering of paints. The CTGONS of hexagonal nanosheets, 2D orientation, chemically treated to the reduced forms and active decoration by RuNPs lead to formation of high catalytic active sites and high loading of targets at the electrode surface. The suitable accommodation of RuNPs/CTGONS to fast response of targets ascertains a high catalytic activity, and fast charge transport. The RuNPs/CTGONS nanocomposite shows an obvious catalytic oxidation signal for DA and AC. The highly sensitive and selective electrode was designed based on RuNPs/CTGONS due to the large peak potentials separation of DA to AC of 0.22 V with sufficient electron mediating behavior. Moreover, the nanocomposite electrode shows individual and simultaneous determination of DA and AC with linear calibration plots from 5–120 μM and 10–120 μM, where their detection limits were calculated to be 0.018±0.002 and 0.023±0.003 μM, respectively. Finally, the analytical application of the RuNPs/CTGONS electrode was applied for the determination of DA and AC in the serum of human blood. [ABSTRACT FROM AUTHOR]