Electrochemical Biosensor Based On Magnetic Graphene And Click Chemistry

The biosensor is a multidisciplinary technology, which plays a very important role in scientific research, industrial production and the people’s lives. Electrochemical biosensor uses an enzyme, antibody, microorganism, etc. as the sensing element and converts the chemical into the electric signal. Since the glucose oxidase enzyme electrode was reported by Clark et al. in 1962, biosensing technology has gradually developed into cross-disciplinary technology combining biology, chemical, physics, medicine and electronics. Because of its selectivity, high sensitivity, rapid analysis, required simple equipment, biosesing technology is one of the current detection methods commonly used in various research fields including clinical diagnostics, environmental monitoring, drug analysis, food safety, and so on.Nanomaterials have unique characteristics including large specific surface area and catalytic properties as well as good biocompatibility. The nanomaterials used in the preparation of nano-biosensors can effectively enhance the current response of the sensor, improve the sensitivity, lower detection limit in the development of biosensors. In this paper, by taking full advantage of biosensing technology and nanotechnology, immobilization of biomolecules on the sensor interface and biosensing signal were studied for the development of novel electrochemical biosensor with high sensitivity, high selectivity and stability. Meanwhile, the obtained electrochemical biosensors for the determination of Sudan in food and neuron-specific enolase(NSE) were succeesfully achieved.The main contents of this paper are as follows:(1) Graphene magnetic nanocomposites were successfully synthesized by in situ growth method of iron oxide on the graphene, which were characterized by transmission electron microscopy and atomic force microscopy. The electrochemical sensor for the determination of Sudan molecules was then constructed by modifying the graphene magnetic nanocomposites onto the surface of glassy carbon electrode. The linear range of the constructed sensor for the detection of Sudan molecules is 5--100μM with estimated detection limit of 0.0033μM(S / N = 3). The sensor also displayed good stability, reproducibility and selectivity. Therefore, the graphene nanocomposites-based electrochemical sensor provided a promising strategy for sensitive detection of Sudan molecules in food.(2) An electrochemical immunosensor for detecting antigen NSE was constructed based on click reaction. Ethynyl functional groups were firstly electrografted on the gold electrode by cyclic voltammetry method, and then conjugated to Ab1 with the azido group in the presence of monovalent copper ion conditions via click reaction. Ab2 molecules were immobilized on the surface of Ag-ATP nanoparticles to be used as electroactive probe. The sandwich-type immunosensor was applied for sensitive detection of neuron-specific enolase(NSE). Its linear range is from 4.5×10-9g m L-1 to 1.0×10-7g m L-1, the detection limit is 8×10-11 g m L-1. Furthermore, the immunosensor showed good selectivity and stability. It is anticipated that this proposed immunosensor could be applied for detection and analysis of NSE in serum.