The Development Of Some Voltammetric Sensors Based On Graphene And Their Application

Chemically modified electrode (CMEs) was a hot area of research in the field of electrochemistry and electroanalysis, owing to its several advantages such as fast response, time-saving, high sensitivity, and excellent selectivity and so on. Graphene (GR), as an ideal nanostructured carbon material of two-dimensional lattice, is an excellent modifier in developing voltammetric sensor, owing to its unique properties, such as large surface area, super conductivity, strong adsorption ability and electrocatalytic activity. In this dissertation, several voltammetric sensors were fabricated based on GR as the main modifier, and were used for detecting several medicinal molecules with rapid response, high sensitivity and wide linear range. The main works of this dissertation were as follows:(1) A simple electrochemical sensor, based on GR and DMF (N, N-dimethyl formamide) composite film-modified glassy carbon electrode, was developed and used for the detection of trace amounts of morin. The oxidation process of morin at sensor was investigated using electrochemical techniques. The proposed method exhibited a good electrocatalytic activity toward the oxidation of morin, owing to the unique electronic and catalytic properties of graphene. Under selective conditions, the detect linear range was given over8.0×10-9～1.0×10-6mol L-1with a detection limit of6.0×l0-9mol L-1. In addition, the fabricated electrode exhibited high sensitivity, good reproducibility and good stability. Then the convenient method was applied to the detection of morin in human serum sample with excellent analytical performance.(2) An ultrasensitive voltammetric sensor, simply coated GR-Nafion suspension on a glass carbon electrode surface, was fabricated and used to investigate the electrochemical behavior of theophylline (TP). The results indicated that this voltammetric sensor exhibited a special recognition capacity to determine TP as well as had high sensitivity due to the excellent characteristics of GR and the adsorption action of Nafion for TP. Under the selected condition using differential pulse voltammetry (DVP), the response peak currents were linear relationship with the TP concentrations in range of1.0×10～3.0×10mol L-1with a low detection limit of6.0×10-9mol L-1. Moreover, according to the results obtained in the analysis of TP in standard samples, it demonstrated the applicability of present method into real sample determination(3) A novel voltammetric sensor based on GR-Nafion and Poly(L-arginine)(L-arg) was constructed by electrodeposited and simple dipping-drying methods and used for high-sensitive determination of terbutaline sulfate (TBS). The resulting sensor showed a significant voltammetric response to TBS due to the synergistic effect of poly(L-arg) and GR-Nafion, in which poly(L-arg) had electrocatalytic ability for TBS and GR provided a large specific surface area, excellent electric conductivity and electrocatalytic activity. The current response was linearly with TBS concentrations in range of4.0×10～5.0×10mol L-1with a detection limit of1.2～10mol L-1. The high sensitivity and selectivity together with the good linear relationship, very easy surface regeneration and good stability at such a modified electrode led us to construct a practical TBS voltammetric sensor successfully. This work promoted the potential applications of graphene-based materials in electrochemical sensors.