The Applications Of Graphene Oxide In Biosensing And Graphene Quantum Dots In Electrochemiluminescence System

Graphene oxide(GO), a single-atom-thick and two-dimensional carbon material, has attracted great attention due to its high electronic conductivity, huge specific surface area, good water-solubility and long-range nanoscale energy transfer characteristics. Furthermore, GO can conjugate with single-stranded DNA(ss DNA) via the π-π stacking interactions. Therefore, GO might be an attractive fluorescent sensing platform material for protein detection. Graphene quantum dots(GQDs), a kind of zero-dimensional graphite nanomaterial, have many unique advantages, such as light resistance, small size, good biocompatibility, adjustable photoluminescence, electrochemiluminescence(ECL) and so on. The emergence of GQDs provides an unprecedented opportunity for the development of bioimaging and optical sensing. In order to investigate the feasibilities of GO in biosensing and GQDs in ECL system, we have done some relevant research in this paper. It mainly includes the following aspects:1. Detection of lysozyme with a fluorescent aptasensor based on energy transfer from carbon dots to graphene oxide.High fluorescence quantum yield carbon dots(CDs) were synthesized using citric acid and ethylenediamine by hydrothermal method. CDs were labeled to one side of lysozyme DNA aptamer. The effective combination of CDs and aptamer were proved by both UV-vis and FTIR. When the system without lysozyme, CDs-aptamer can be adsorbed on the surface of GO, the fluorescence can be quenched effectively. However, in the present of target lysozyme, lysozyme could bind with the aptamer, and the CDs-aptamer was desorpted from surface of GO subsequently. In turn, the fluorescence of CDs-aptamer was recovered. The concentration of lysozyme could be determined. Under the optimal experimental conditions, the standard curve and the regression equation of this system were obtained, and the detection limit was 1.0×10-6 mg/m L. So this system had a good selectivity and can be successfully used for the detection of lysozyme in human serum.2. Determination of L-cysteine by FIA-ECL of Ru(bpy)32+-GQDs system.GQDs which we synthesized have excellent water-soluble, environmentally friendly and high biocompatibility. A one-step solvothermal route from GO is implemented. Herein, GQDs are introduced into classic Ru(bpy)32+-ECL system, due to the sensitizing effect to ECL signal of Ru(bpy)32+. A new ECL method for detecting of L-cysteine was developed. This method has high sensitivity and a wide linear range, and the detection limit was 7.26×10-4 mg/m L.