Study On Luminol Electrochemiluminescence Immunosensor Constructed By Carbon And Metal Nanomaterials

Nanomaterials have been widely used in fabricating biosensors, due to its interesting advantages, such aslarge surface areas, good adsorption capacities, biocompatibilities, strong adsorption ability and electrical catalytic activities. Particularly attractive for numerous bioanalytical applications are carbon nanotubes (CNTs), graphene, metal and metallic oxide nanocomposite materials and quantum dot (QD) nanoparticles.The ECL immunosensor, combined the ECL technique and immunoassay technique, has become an attractive method because of its advantages such as high selectivity, high sensitivity and rapid detection. This is based on these advantages of nanomaterials. We use carbon nanotubes/graphene composite nanomaterials, gold/platinum alloy nanoparticles, silver nanoparticles/graphene composite nanomaterials, hemin/graphene nanomaterials, polyamidoamine/ZnO nanorods and other nanomaterials to construct a series of excellent performed sandwich immunosensors. Scanning electron microscope (TEM) and electrochemical technology are also used to characterize the nanomaterials, the preparation process of the electrode, the optimization process and the properties.In our paper, research work is carried out from the aspects as follows:Part 1 Study on ultrasensitive luminol cathodic ECL innunosensor based on glucose oxidase and nanocomposites:Graphene-carbon nanotubes and gold-platinum alloyIn the present study, a novel and ultrasensitive electrochemiluminescence (ECL) immunosensor based on luminol cathodic ECL was fabricated by using Au nanoparticles and Pt nanoparticles (nano-AuPt) electrodeposited on graphene-carbon nanotubes nanocomposite as platform for the detection of carcinoembryonic antigen (CEA). For this introduced immunosensor, graphene (GR) and single wall carbon nanotubes (CNTs) dispersed in chitosan (Chi-GR-CNTs) were firstly decorated on the bare gold electrode (GE) surface. Then nano-AuPt were electrodeposited (DpAu-Pt) on the Chi-GR-CNTs modified electrode. Subsequently, glucose oxidase (GOD) was employed to block the non-specific sites of electrode surface. When glucose was present in the working buffer solution, GOD immediately catalyzed the oxidation of glucose to in situ generate hydrogen peroxide (H2O2), which could subsequently promote the oxidation of luminol with an amplified cathodic ECL signal. The proposed immunosensor was performed at low potential (-0.1 to 0.4 V) and low concentration of luminol. The CEA was determined in the range of 0.1 pg/mL to 40 ng/mL with a limit of detection down to 0.03 pg/mL(S N-1 = 3). Moreover, with excellent sensitivity, selectivity, stability and simplicity, the as-proposed luminol-based ECL immunosensor provided great potential in clinical applications.Part 2 Study on enhanced electrochemiluminescence of luminol based on synergetic catalysis of hemin and silver nanoparticlesA novel and ultrasensitive electrochemiluminescence (ECL) immunosensor, which was based on the amplifying ECL of luminol by hemin-reduced graphene oxide (hemin-rGO) and Ag nanoparticles (AgNPs) decorated reduced graphene oxide (Ag-rGO), was constructed for the detection of carcinoembryonic antigen (CEA). For this proposed sandwich-type ECL immunosensor, Au nanoparticles electrodeposited (DpAu) onto hemin-rGO (DpAu/hemin-rGO) constructed the base of the immunosensor. DpAu had outstanding electrical conductivity to promote the electron transfer at the electrode interface and had good biocompatibility to load large amounts of primary antibody (Ab1), which provided an excellent platform for this immunosensor. Moreover, AgNPs and glucose oxidase (GOD) functionalized graphene labeled secondary antibody (Ag-rGO-Ab2-GOD) was designed as the signal probe for the sandwiched immunosensor. Not only did the hemin-rGO improve the electron transfer of the electrode surface, but hemin also further amplified the ECL signal of luminol in the presence of hydrogen peroxide (H2O2). With the aid of Ag-rGO-Ab2-GOD, enhanced signal was obtained by in situ generation of H2O2 and catalysis of AgNPs to ECL reaction of the luminol-H2O2 system. The as-prepared ECL immunosensor exhibited excellent analytical property for the detection of CEA in the range from 0.1 pg/mLto 160 ng/mL with a detection limit of 0.03 pg/mL (S N-1 = 3).Part 3 Study on sensitive electrochemiluminescence immunosensor base on immobilizing luminol on dendrimer functionalized ZnO nanorodsIn this study, we constructed a novel electrochemiluminescence (ECL) immunosensor for sensitive and selective detection of carbohydrate antigen 15-3 (CA15-3) by using polyamidoamine (PAMAM)-functionalized ZnO nanorods (ZNs-PAMAM) as carriers. PAMAM dendrimers with hyper-branched and three-dimensional structure were used as linked reagents for co-immobilization of luminol and CA15-3 detection antibody on the ZNs to prepare the signal probe. In addition, ZNs could hasten the decomposition of H2O2 to generate various reactive oxygen species (ROSs) which accelerated the ECL reaction of luminol with amplifi ed ECL intensity. Compared with luminol in the detection solution, the ECL efficiencies of luminol could be improved by immobilizing luminol on the electrode due to the smaller distance between luminescence reagent and the electrode surface. Moreover, the electrodepositing gold nanoparticles (AuNPs) on the bare glass carbon electrode (GCE) with enhanced surface area could capture a large amount of primary anti-CA15-3 to improve the sensitivity of the immunosensor. Under the optimized experimental conditions, a wide linear range of 0.1-120 U/mL was acquired with a relatively low detection limit of 0.033 U/mL (S N-1 = 3)for CA15-3.