Research and Application of graphene oxide - based electrochemical biosensor
|Keywords||Graphene Oxide biosensor electrochemistry immunosensor|
Graphene discovered in 2004 has attracted intensive interest because of its two dimensionality and unique physical properties such as a small size, high specific surface area, surface reactivity, catalytic efficiency. It can be used to modify electrodes, in order to reduce the over potential of redox reactions, improve the reversible oxidation and reduction of biological molecules. Its large specific surface area not only provides conducive to immobilization of biomolecules, but also promotes electron transfer between protein active centers and electrode surface. These features are of great significance for improving the sensitivity and stability of biological detection. Therefore the field of bio-sensors has opened up broad prospects. Graphene oxide with rich groups has a unique advantage in the functional graphene.Here we report a novel electrochemical sensor modified by graphene oxide and its applications. The research is detailed as follows:1. Preparation graphene oxide by chemical methodGO was prepared by modified Hummers’method from natural graphite flakes. GO suspension in water was dip-coated onto the Au working electrodes. The SEM images of GO show almost perfect connection between each flat domains. A single GO sheet was about 3μm. In the Raman spectra of the GO, the peak at 1580cm-1 (G-band) was related to the vibration of sp2-bonded carbon atoms, and the peak at 1350cm-1 (D-band) was associated with vibrations of carbon atoms. The electrochemical reduction of graphene oxide made the conductivity of graphene oxide increase by 4 orders of magnitude.2. The electrochemical electrode modification with graphene oxide of the chipGO suspension was directly dip-coated onto the substrates of Au. It could be seen that the peak of GO sensor was 4μA, shown in the picture of CV spectrum. The curve of GO on Au electrode increased by 1μA as compared with Au electrode. Graphene oxide was modified with EDAC/NHS to get modified graphgene oxide (MGO), by which the electrodes can be connected with proteins. Fluorescence characterization results showed that the graphene oxide was modified with an effective combination of bovine serum albumin.3. Application of the electrochemical immune sensors modified by graphene oxideA tuberculosis (TB) specific antigen bound with the surface of the electrochemical electrode modified by graphene oxide constituted an immune sensor chip for TB detection. Positive for tuberculosis antibody were detected in serum, the peak current density decreased 3μA because of antigen-specific antibody response. Such results showed the potential application of the immunosensor.