The Study Of Bioelectrochemistry Sensors Based On Nanometer Materials And Ionic Liquids

Metal nanoparticles and graphene have been used to fabricate electrochemical sensors due to their high electrical conductivity, large specific surface area and high enzyme loading. Moreover, ionic liquids(ILs) possess unique properties such as high conductivity and good biocompatibility, which can be used as not only the solvents for stabilization of metal nanoparticles and immobilization of enzymes, but also the modifier for the chemically modified electrodes. In addition, recent studies found that the synergistic effect of nanometer materials and ionic liquids could significantly improve the properties of biosensors. Therefore, this dissertation focused on the fabrication of three novel biosensors based on nanometer materials and ILs, and then researched their application. The main contents were summarized as follows:1. A novel scheme for fabrication of hydrophobic ionic liquid-capped gold nanoparticles(IL-capped Au NPs) modified electrode was presented and its potential application for cholesterol biosensor was investigated. Highly stable gold nanoparticles were characterized by UV–vis absorption spectroscopy and transmission electron microscopy(TEM). Cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS) indicated that IL-capped Au NPs nanocomposites showed excellent electrical conductivity. Furthermore, cholesterol oxidase(Ch Ox) was directly immobilizedthe IL-capped Au NPs nanocomposite, and then the direct electrochemistry of Ch Ox on the modified electrode was obtained. As a new platform in cholesterol analysis, Ch Ox-IL-capped Au NPs/GCE exhibited a linear response to cholesterol in the range of 1×10-7 to 5×10-5 mol/L with a detection limit of 3.3 ×10-8 mol/L. Therefore, hydrophobic ionic liquid-capped gold nanoparticles would serve as a good candidate material to construct the related enzyme biosensors.2. From the above chapter, we found that the hydrophobic ILs on the electrode surface were beneficial to the adsorption of hydrophobic target analytes. Meanwhile,graphene possesses unique properties like extraordinary electrical conductivity and large surface area. In this chapter, a novel sensor for the sensitive determination of L-tyrosine was fabricated based on the composite materials of SDBS modified graphene, CS and ionic liquid composite(SDBS-Gr-CS-IL). The composite was characterized by different methods including transmission electron microscopy(TEM), cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS).The constructed electrode exhibited good electrochemical response of L-Tyr, with wide linear range(1×10-7~1×10-5 mol/L and 1×10-5 ~1.2×10-4 mol/L) and a low detection limit of 3.3×10-8 mol/L. Finally, the fabricated biosensor was successfully used for the selective determination of L-tyrosine in real samples.3. In this chapter, a novel rutin sensor was fabricated based on functionalized graphene and ionic liquid composites by electrochemical reduction method. The f Gr-IL composite modified electrode was characterized by different methods including cyclic voltammetry(CV) and electrochemical impedance spectroscopy(EIS). The constructed electrode exhibited good electrochemical response of rutin,and a wide linear range from 1.0×10-8to 8×10-5mol/L with a detection limit of3.3×10-9 mol/L.