Graphene Based Electrochemical Sensor For Endocrine Disrupter BPA And Biological Molecule Coenzyme NADH

Graphene, a kind of new carbon nanomaterial, has the excellent electrical and electrochemical properties such as outstanding electric conductivity, large specific surface area, zero band gaps, high carrier mobility and so on. Based on the outstanding properties of graphene, this research established electrochemical sensors for endocrine disrupter BPA and biological molecule coenzyme NADH. These electrochemical sensors are simple to establish and experiments show that they have satisfactory analytical performance towards the target analytes.The main contents can be summarized as follows:1. Firstly, we synthesized the graphene/nano-gold composites (rGO-AuNPs), and used these composites as the electrode substrate. On the one hand, the excellent electrical conductivity of rGO-AuNPs can preliminary enhance the electric current signal of bisphenol A (BPA). On the other hand, the rGO-AuNPs electrode substrate can load nano SiO2 through electrostatic attraction. The abundant silicon hydroxyl groups on nano SiO2 can form hydrogen boding force with phenolic hydroxyl groups of bisphenol A, and this force can realize the adsorption and enrichment of bisphenol A, enhance the electric current signal once again. Thus, SiO2/rGO-AuNPs modified electrode can dual amplify the electric current signal through electrode substrate improvement and adsorption of bisphenol A. As a bisphenol A electrochemical sensor, the SiO2/rGO-AuNPs/GCE displays a low detection limit of 5.0×10"9 mol L-1 (S/N=3), and possess good stability, reproducibility and selectivity.2. A simple, green and controllable electrochemical method, pulsed potentiostatic method (PPM), was employed to electro-reduce and electro-deposit graphene from graphene oxide (GO) dispersion to the electrode surface, establishing an NADH electrochemical sensor (PPM-ERGO/GCE) in single-step and avoid the graphene from aggregation. Compared with bare GCE and the graphene electrochemically reduced by cyclic voltammetry modified elelctrode (CV-ERGO/GCE), NADH permit effective low potential and enhanced current response at PPM-ERGO/GCE, indicating that pulsed potentiostatic method can recover the outstanding electrical properties of graphene. Under the detection potential 0.1 V, the detection limit of NADH on PPM-ERGO/GCE was 5.0×10-7 mol L"1 (S/N = 3) and the sensor has acceptable reproducibility, good stability and anti-interference ability. Furthermore, the PPM-ERGO/GCE was used to detecting NADH in real sample and a satisfactory result was obtained.