Biosensor Based On Graphene Oxide/Polyaniline

The poor dispersion of graphene nanosheets, which results from Van der Wals forces between layer and layer in graphene, is of crucial importance for their applications. Graphene Oxide/Polyaniline (GO/PANi) nanocomposites, one kind of the functionalized graphene, have excellent electrical, optical and other physical and chemical properties, It has been demonstrated that Graphene Oxide/Polyaniline (GO/PANi) nanocomposites have been widely studied in the area of sensors, nanoelectronic devices, energy storage and conversion, bioscience and technology.This dissertation focuses on the studies on the biosensor based on the GO/PANi nanocomposite with the combination of nanotechnology, analytical chemistry, and biotechnology.Main work as follows:1. Fabrication of GO/PANi/CdSe Nanocomposites for Sensitive Electrochemiluminescence BiosensorA novel graphene oxide sheets/polyaniline/CdSe quantum dots (GO/PANi/CdSe) nanocomposites were successfully synthesized and used for the sensitive electrochemiluminescence (ECL) biosensing. The GO/PANi/CdSe nanocomposites were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), ultraviolet-visible (UV-vis) absorption spectroscopy, photoluminescence (PL) spectroscopy and Fourier transform infrared (FTIR) spectroscopy. Finally, the nanocomposites were employed to construct the biosensor via layer-by-layer assembly for the ECL detection of Cytochrome C (Cyt C). The whole process was characterized by cyclic voltammogram (CV) and electrochemical impedance spectroscopy (EIS). Experimental parameters such as the ratio of GO/PANi, the K2S4O8concentration and the pH value of electrolyte solution were studied to investigate the effect on the ECL intensity. Under the optimized conditions, the ECL intensity decreased linearly with the Cyt C concentrations in the range from5.0×10-8to1.0×10-4M with detection limit of2.0×10-8M. Besides, the as-proposed biosensor exhibits high specificity, good reproducibility, and stability, and may applied in more bioanalytical systems.2. Electrochemiluminescence immunosensor based on graphene oxide nanosheets/polyaniline nanowires/CdSe quantum dots nanocomposites for ultrasensitive determination of human interleukin-6A novel graphene oxide nanosheets/polyaniline nanowire arrays/CdSe quantum dots (GO/PANi/CdSe) nanocomposites is successfully synthesized and use as ECL immunosensor for detection of human interleukin-6(IL-6). The as-prepared GO/PANi/CdSe hybrid shows excellent biocompatibility, dispersity and solubility. Electrochemiluminescence (ECL) of CdSe quantum dots (QDs) was greatly enhanced by combining with GO/PANi nanocomposites. Herein, this hybrid was applied to develop an ultrasensitive ECL immunosensor for detection of IL-6. The ECL immunosensor has a sensitive response to IL-6in a linear range of0.0005-10ng mL-1with a detection limit of0.17pg mL-1. The ECL immunosensor exhibits high specificity, long-term stability and excellent reproducibility, which make it possible to be used in clinical application.3. Preparation and electrochemical biosensor of GO/PANi nanocompositesThe novel biosensor based on GO/PANi composites was successfully fabricated. Graphene oxide (GO) was prepared from graphite powder by a modified Hummers method. GO/PANi composites was synthesized by facile in-situ polymerization using GO and aniline monomer as the raw materials. The nanocomposites which showed large specific surface and good biocompatibility was used to construct the electrochemical biosensor of dopamine. The results show that the biosensor has high sensitivity and fast response for dopamine. The linear range of the biosensor to dopamine is from1.0×10-8M to1.×10-5M with the detection limit of1.02×10-9M. The biosensor prepared shows fast sense, high sensitivity, good stability and specificity and has broad potential application in bio-analysis.