The Preparation Of Graphene-based Nanocomposites Modified Electrodes And Application In Electroanalytical

In this paper, we studied the electrochemical behavior of several biological molecules on the graphene-based nanocomposites modified electrodes and established the electrochemical analysis of corresponding biomolecules. The major contents including:Pt/graphene, Cu2O/Graphene and CuS/Graphene were synthesized through liquid phase reduction method, poly (L-Arginine)/graphene composite film modified electrode was successfully prepared via a facile one-step electrochemical method. These nanocomposites were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and fourier transform infrared. Meanwhile, graphene-based nanocomposites modified electrodes were prepared and used to investigate the electrode behavior, the analytical conditions, the actual sample analysis and the interference tests of several kinds of biological molecules. The major contents are described as follows:1. Pt/graphene nanocomposites were rapidly synthesized via a one-step microwave-assisted method, and characterized by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The results exhibited that Pt nanoparticles (NPs) were well-dispersed on the graphene surface with the average diameter of about3.2nm. Cyclic voltammetry results demonstrated that the Pt/GN nanocomposites modified glassy carbon electrode exhibited excellent electrocatalytic activity to the reduction of H2O2. Amperometric response results indicated that the modified elelctrode displayed a fast response of less than4s with linear range of2.5×10-6-6.65mol·L-1and a relatively low detection limit of8×10-7mol·L-1(S/N=3). In addition, the Pt/GN/GCE showed good selectivity for H2O2detection in the presence of several interfering species under physiological pH condition.2. Poly (L-Arginine)/graphene composite film modified electrode was successfully prepared via a facile one-step electrochemical method and used for simultaneous determination of uric acid (UA), xanthine (XA) and hypoxanthine (HX). The electrochemical behaviors of UA, XA and HX at the modified electrode were studied by cyclic voltammetry and differential pulse voltammetry (DPV), and showed that the modified electrode exhibited excellent electrocatalytic activity towards the oxidation of the three compounds. The calibration curves for UA, XA and HX were obtained over the range of1.0×10-7-1.0×10-5mol·L-1,1.0×10-7-1.0×10-5mol·L-1and2.0×10-7-2.0×10-5mol·L-1by DPV, respectively and the detection limits for UA, XA and HX were5×10-8mol·L-1,5×10-8mol·L-1and1×10-7mol·L-1(S/N=3), respectively. With good selectivity and high sensitivity, the modified electrode has been applied to simultaneous determination of UA, XA and HX in human urine with satisfactory result.3. Cu2O/Graphene nanocomposites were synthesized via reduction of ethylene glycol. Its morphology was characterized by X-ray diffraction, transmission electron microscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy. Cyclic voltammetry was used to evaluate the electrochemical response of a glass carbon electrode (GCE) modified with the nanocomposite towards dopamine (DA). Compared to the bare GCE, the Cu2O nanoparticles modified electrode and the graphene modified electrode, the nanocomposites modified electrode displays high electrocatalytic activity in giving an oxidation peak current that is proportional to the concentration of DA in the range from1.0×10-7to1.0×10-5mol·L-1,with a detection limit of1×10-8mol·L-1(S/N=3). The modified electrode shows excellent selectivity and sensitivity even in the presence of high concentration of uric acid and can be applied to determine DA in real samples with satisfactory results.4. CuS/graphene nanocomposites were synthesized via reduction of ethylene glycol and used for determination of esculetin. Electrochemnical measurement indicates that CuS/graphene nanocomposites modified electrode exhibits an excellent electrochemical activity of esculetin. Under the optimized conditions, the modified electrode was successfully employed for the voltammetric determination of esculetin with a low detection limit, wide linear range.