Eletrochemical Immunosensor Based On Graphene Nanocomposite

Nanomaterial refers to the three-dimensional spatial scale in at least one dimension in nanometers (0.1-100nm) material. It has specific physical characters including the surface effect, volume effect and dielectric confinement effect. Graphene is a flat monolayer of carbon atoms tightly packed into a two-dimensional honeycomb lattice. Its thickness is only0.335nm. It has stable mechanical performance, excellent conductivity and biologicial compatibility. Recently, it has been widely used in electrochemical sensor and biosensor.Immunosensor has good specificity and stability. It combines the advantages of immune detection and biological sensor technique, and this can reduce the analytical time and improve the detection sensitivity. The development of nanomaterial greatly enhances the sensitivity and stability of the immunosensor.In this paper, some immunosensors were prepared based on graphene and Au nanoparticles. SEM and electrochemical techniques were used for the characterization of the immunosensors. The application of the developed immunosensors was studied. The work is as follows:1. TiO2-graphene was dispersed in chitosan solution and then the mixture was coated on glassy carbon electrode. The negatively charged AuNPs can be adsorbed on the positively charged chitosan/TiO2-GR composite film by electrostatic adsorption, and then is used to immobilize α-fetoprotein antibody for the construction of novel immonosensor. The good conductivity of the nanocomposte film effectively improved the transfer of electrons and therefore enhanced the detection sensitivity. The excellent membrane-forming ability of chitosan and good biocompatibility of Au nanoparticles were benefit to immobilizing antibody and maintaining its biological activity. A wide detection range (0.1-10.0and10.0-300.0ng mL-1) for α-fetoprotein was obtaine, with detection limit of0.03ng mL-1(S/N=3). The sensing strategy developed possesses simplicity, good sensitivity and selectivity.2. TiO2-graphene was dispersed in nafion solution and then the mixture was coated)n glassy carbon electrode. The thionine was immobilized on the electrode by chemical adsorption. The negatively charged AuNPs can be adsorbed on the positively charged:hionine by electrostatic adsorption, and then is used to immobilize carcinoembryonic antigen antibody for the construction of novel immonosensor. The SEM and electrochemical technique were used to characterize the biosensor. Because of the synergistic effect of Au nanoparticels, thionine and the unique properties of fiO2-graphene, the obtained immunosensor exhibited a wide linear response to carcinoembryonic antigen in two range from0.1to10.0and10.0to120.0ng mL-1with a relatively low detection limit of0.01ng mL/1(S/N=3). The immunosensor has good stability and reproducibility, and can be used for real sample analysis.