Construction Of Electrochemical Biosensors Based On Functionalized Graphene And Their Application Research In Bioassay

Electrochemical sensors are a kind of chemical sensors that can record the electric signals of charge migration occurred on the interface of the electrode and electrolyte-phase. In recent years, electrochemical sensors have been becoming an important detection technology in the field of analysis and detection due to its virtues, such as easy-operation, high- selectivity, fast-analysis, low cost, and online analysis, etc., compared with traditional methods. Much more applications of electrochemical sensors have been taken in the fields of pharmacology, environmental science, food safety, pharmaceutic al development, agricultural production and fermentation industry. Since Andre Geim and Konstantin Novoselov won the Nobel Prize for physics in 2010, graphene is becoming very attractive to researchers at home and abroad.In our work, a kind of electroche mical sensor was prepared with graphene and its composite fabricated at home. Coupled with capillary electrochemiluminescence(EC L), glucose biosensors and P450 enzyme biosensor, the detection of 5-hydroxytryptamine, tyramine, glucose and phenacetin was realized with the obtained graphene electrochemical sensor. Four chapters are divided in the paper:Chapter 1: The progress and applications of electrochemical sensors and graphene modified electrodes are reviewed.Chapter 2: A highly sensitive and stable so lid-state electrochemiluminescence(EC L) sensor was developed based on tris(2,2'-bipyridyl)ruthenium(II)(Ru(bpy)32+) integrating with 2,2-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid)(ABTS) functionalized graphene. Ru(bpy)32+ is incorporated with the ABTS functionalized graphene based on not only the ?-? stacking but also electrostatic interactions. Coupled with capillary electrophoresis(CE), this EC L sensor was used to detect tyramine and 5-hydroxytryptamine(5-HT) based on their quenching effects for the Ru(bpy)32+/tripropylamine(TPA) system. The quenching mechanism was illustrated and the conditions for C E separation and EC L detection were optimized. Based on an S/N = 3, the limit of detection(LOD) for tyramine and 5-HT was 0.1 ?M and 0.02 ?M, respectively. The applicability of the proposed method was further illustrated in the determination of tyramine and 5-HT in human plasma samples from small intestine carcinoid patients.Chapter 3:Functionalized by Poly(diallyldimethylammonlum chloride), the graphene(G) was positively charged. Then it was electrostatically self-assembled with negatively charged gold nanoparticles(Au NPs), to obtain the compound material G/Au NPs. In order to verify the application of this material, we droped it to the glassy ca rbon electrode(GCE), with glucose oxidase(GOD) as a template, a glucose biosensor of G/Au NPs/GO D/GCE was successfully developed. The average electron transfer rate is 1.64 s-1. The glucose biosensor showed a good linear range from 1.0m M to 9.0m M, with a low detection limit of 0.1m M(S/N=3). The kind of biosensor successfully determined the serum sample, with the recovery being 95.7%-107.6%. Therefore, it's conclusioned that G/Au NPs compound material provided excellent electrical conductivite and suitavle microenvironment for GOD, which also provide a favorable platform for the immovilization of other enzymes or proteins.Chapter 4: The immobilization of P450 on the modified electrodes was introduced. With prepared cationic polyacrylamide modified graphene as a platform, the P4501A2 enzyme was immobilized via physical and chemical properties and applied for studying the drug metabolism. Sensitivity and limit of detection of The home- made CYP1A2/CPAM-G/GCE were 1.333?A(?mol/L)-1 cm-2 and 5.57?mol/L, respectively. And the electrochemical sensor coupled with CYP450 exhibits ambitions in the evaluation of drug interactions and can be a reference in vitro construction of other biological systems.