Electrodeposited reduced graphene oxide incorporating polymerization of L-lysine on electrode surface and its application in simultaneous electrochemical determination of ascorbic acid, dopamine and uric acid

This paper demonstrates a novel strategy for the construction of a graphene hybrid composites film, which was fabricated by electrodeposited reduced graphene oxide (ERGO) incorporating polymerization of L-lysine (PLL) onto glassy carbon electrode (GCE). Here we show that graphene films can be prepared on electrodes directly from GO dispersions by one-step electrodeposition technique based on electropolymerized PLL as a positively charged polymer interface to adsorb negatively charged GO nanosheets through electrostatic attraction. The thickness of graphene film can be easily controlled by using the electrodeposition technique, a distinct advantage over previously developed methods. The electrochemically reduced process of GO and electropolymerization of L-lysine were investigated by cyclic voltammetry with a wide potential range. The surface morphology of the modified electrode was characterized by scanning electron microscopy. The ERGO/PLL/GCE shows conducive to electron transfer kinetics for Fe(CN)₆^3 −/Fe(CN)₆^4 − redox probes, compared with bare GCE, PLL/GCE and ERGO/GCE. The electrochemical behaviors of ascorbic acid (AA), dopamine (DA) and uric acid (UA) at ERGO/PLL/GCE were investigated by cyclic voltammetry, and the results suggest that the modified electrode exhibits enhanced electrocatalytic activity toward these important molecules. Under physiological condition and in the co-existence system of AA, DA and UA, the ERGO/PLL/GCE showed linear voltammetric responses in the concentration of 100 μM–1200 μM for AA, 2.0 μM–60 μM for DA and 20 μM–200 μM for UA, and with the detection limits (S/N = 3) of 2.0 μM, 0.10 μM and 0.15 μM for AA, DA and UA, respectively. The developed method has been applied to simultaneous determination of AA, DA and UA in human urine with satisfactory recoveries of 104.2%, 95.4% and 99.9%, respectively. This work demonstrates that the attractive features of ERGO/PLL provide promising applications in simultaneous determination of AA, DA and UA in physiological and pathological studies.