Modification Of Graphene Composites And Its Application In Electrochemical Biosensor

In this work, Graphene oxide(GO) was synthesized by the Hummers method. The GO was reducted for Graphene(Gr). Gr was fabricated hexadecyl trimethyl ammonium bromide(CTAB) and dodecyltrimethylammonium bromide(DTAB), and applied to fabricate electroactive Mb-Gr-CTAB and Mb-Gr-DTAB biosensor by incorporating with myoglobin(Mb). The as-prepared Mb-Gr-CTAB composite films was characterized by scanning electron microscopy(SEM), Fourier transform infrared spectra(FT-IR), UV-Vis adsorption spectroscopy, cyclic voltammetry(CV), chronoamperometry, alternating current impedance(AC impedance), square-wave voltammetry(SWV) and other techniques. FT-IR experimental showed that GO was successfully reduced to Gr. SEM experimental data suggested that Mb may have incorporated in the composites films and interacted with the Gr-CTAB composite films, which changed the surface morphology of the composite films. UV-Vis experiment demonstrated that Mb in the films retains its secondary structure at medium p H. The composite films on the electrodes showed a pair of well-defined and nearly reversible cyclic voltammetry peaks at-0.31 V in p H 7.0 buffers, characteristic of the Mb heme Fe(III)/Fe(II) redox couple. The electrochemical parameters such as apparent heterogeneous electron transfer rate constant(ks) and formal potential(Eo’) were estimated by fitting the data of SWV with nonlinear regressionanalysis. The composite films exhibited excellent electrocatalytic reduction to sodium nitrite, oxygen, TCA and hydrogen peroxide, with wider linear ranges and low detection limitsand, showed good reproducibility and stability. In addition, the composite films of Mb-Gr-DTAB was also characterized in this paper. Electrodes modified the composite films also showed good electrochemical properties with DTAB and Gr. Experimental data demonstrated that the electrochemical biosensor obtained by the two surfactant have high sensitivity, good stability and good electochemical and biology catalytic activity. The effects of different carbon chain lengths of surfactant on the direct electron transfer(DET) between Mb and GCE were also studied. Electrochemical experimental results showed that the Mb-Gr-CTAB and Mb-Gr-DTAB composite films had good DET and good electrocatalytic properties. This provided the theoretical support for its application in electriccatalytic performance. Modified graphene as a new material may provide a promising platform for the fabrication of the biosensor and biocatalysis.