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 mu M-1200 mu M for AA, 2.0 mu M-60 mu M for DA and 20 mu M-200 mu M for UA, and with the detection limits (S/N = 3) of 2.0 mu M, 0.10 mu M and 0.15 mu M 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. (C) 2016 Elsevier B.V. All rights reserved.