Study Of Biomolecules Determination By Graphene/Polyaniline Composite Film Modified Electrode

The chemically modified electrodes is an important part of electrochemical researchand the frontier subject. Due to the superior chemical properties, the chemically modifiedelectrodes based on the new type nanometer material and novel nanoscaled hybridmaterials widely studied by analysis of the workers. In this paper, the composite filmmodified electrode was prepared by addition of the graphene/polyaniline composite ontothe surface of glassy carbon electrode, the composite was synthesized by an in situpolymerization procedure. Combined with this characteristics which electro-analyticalmethod is very sensitive, selective with simple instrument, study of biomoleculesdetermination by the composite film modified electrode, and the modified electrode wasapplied to the determination of sample. It provides new ideas and technologies for thestudy of electrochemical theory and sensor development, it laid the foundation foroptimization and practical electrochemical sensors. The following researches had beencarried out in four aspects and the results as followed:1) The graphene was prepared by chemical reduction of graphite oxide, and thegraphene/polyaniline composite was synthesized by an in situ polymerization procedure.The morphology and structure of composite was characterized by SEM, XRD and FTIR, itproved successful synthesis.2) The graphene/polyaniline composite was used to modify bare glass carbonelectrode by drop-coating method, the electrochemical behavior of ascorbic acid (AA) atthe graphene/polyaniline composite film modified electrode was studied by cyclicvoltammery. Determined the testing conditions: water as dispersant,5μL1mg/Lcomposite dispersion, in0.1mol/L phosphate buffer solution (pH3.0),50mv/s scan rate.The peak currents varied linearly with the concentration of AA over the range from5.0×10-7to1.0×10-3mol/L. In addition, the modified electrode has good reproducibilityand stability for determination of AA. It was applied to the determination of trace AA inVitamin C samples.3) The modified electrode was applied to the determination of dopamine (DA).Determined the testing conditions:8μL1mg/L composite dispersion, in0.1mol/Lphosphate buffer solution (pH4.0),50mv/s scan rate, a new determination method of DAwas established. The anodic peak current of DA was linearity with its concentration in the range of8.0×10-7～5.0×10-3mol/L. The reproducibility and stability for determination ofDA were evaluated with satisfactory results, the modified electrode performed excellentelectrocatalysis in redox behaviors of DA and AA, the modified electrode has goodselectivity in the mixture sample, it was applied to determine DA in hydrochlorideinjection solution.4) The electrode process kinetic parameters of uric acid (UA) were determined. Theelectron transfer coefficient α is0.67, the apparent diffusion coefficient is2.6×10-6cm2/s.The peak potential of AA, DA and UA were separate obviously on the composite modifiedelectrode.