Titanium dioxide anchored graphene oxide nanosheets for highly selective voltammetric sensing of dopamine

The authors report on an efficient method for the voltammetric sensing of dopamine (DA) by using an electrode modified with alternating monolayers of graphene oxide (GO) and Titanium dioxide (TiO2) nanoparticles anchored GO nanosheets (NSs)). The as-prepared nanostructures were characterized by photoluminescence spectroscopy, powder X-ray diffraction, Raman spectroscopy, FT-IR spectroscopy, transmission electron microscopy, scanning electron microscopy, atomic force microscopy and Energy Dispersive X-ray Analysis (EDAX) techniques. The GO/TiO2 nanocomposite (NC) was deposited on a glassy carbon electrode (GCE), where it displayed an excellent electrocatalytic activity toward the oxidation of DA, owing to its excellent conductivity, high specific surface area, enhanced interfacial contact and more negative zeta potential. Figures of merit include (a) a fast response (5 s), (b) a wide linear range (between 0.2 and 10 mu M of DA) (c) a particularly low detection limit (27 nM), (d) a working potential as low as 0.25 V (vs. Ag/AgCl) and (e) a sensitivity of 1.549 mu A center dot mu M-1 center dot cm(-2). The GO/TiO2/GCE exhibited excellent selectivity over the other interferences as revealed by the differential pulse voltammetric and amperometric studies. The analysis of spiked urine samples resulted in recoveries in the range of 96 to 106%, with RSDs between 3.8 and 5.2%.