| Functional composite material has many advantages such as unique optical and electric property, good stability, small dimension effect, surface effect and good biocompatibility. Moreover, its surface is easy to be functionalized. So its application in fields of biosensors is widely attracted by researchers.Electrochemical immunosensor is one kind of biosensors which combines methods of electrochemical analysis and immunoassay. It is rapid, sensitive, high selective and simplicity. Electrochemiluminescence immunosensor is the combination of immunosensor and electrochemiluminescence. It has advantage of them, such as good repeatability and selectivity. But the most outstanding merit is its high sensitivity and low detection limit. So it is meaningful to study on high sensitive, rapid and effective immunosensor by employing composite materials.Part 1 Research on an immunosensor based on nano gold/functional chitosan biology composite membrane for detection of carcinoembryonic antigenChitosan and cysteine were crosslinked by EDC·HCl and NHS, which formed the functional biomembrane with thiol group and amino group. Nano gold can be adsorbed to the electrode surface by the active groups, then anti-CEA was adsorbed to prepare carcinoembryonic antigen immunosensor. The experiment indicated that, this sensor had good electric current response on CEA by using potassium ferricyanide as oxidation-reduction probe. In this experiment, it is simple to prepare and operate the sensor of high sensitivity. This method can be used for detection of carcinoembryonic antigen.Part 2 Porous redox-active Cu2O-SiO2 nanostructured composite film:preparation, characterization and application for a label-free amperometric ferritin immunosensorA novel Cu2O-SiO2 nanostructured particle was synthesized by a solution-phase method and was adopted for construction of a label-free amperometric immunosensor. Differently to other nanomaterials, the porous Cu2O-SiO2 nanoparticles had good redox electrochemical activity, large surface-to-volume ratio, film-forming ability and high stability. The physical morphology and structure of Cu2O-SiO2 nanoparticles were examined by scanning electron microscope (SEM) and transmission electron microscopy (TEM). The chemical component of Cu2O-SiO2 was confirmed by X-ray photoelectron spectroscopy (XPS) and auger electron spectra (AES). The immunosensor exhibited a good response to ferritin in ranges with a detection limit of 0.4 ng/mL. This immunosensor constructed by the composite nanomaterial can avoid the complexity of immombilizing normal electroactive material, and the novel nanomaterial is hopeful to apply in other immunosensors' fabrication.Part 3 Ru(bpy)32+-doped silica composite nanoparticles labeling for a sandwich-type electrochemiluminescence immunosensorA new approach was established to construct a sandwich-type electrochemiluminescence (ECL) immunosensor by using Ru(bpy)32+-doped silica (abbreviated as Ru-SiO2) nanoparticles to label secondary antibody. Firstly, carboxylate-terminated multi-walled carbon nanotubes (MWCNTs) were modified on the electrode to bond with avidin. Subsequently, biotinylated antibodies were immobilized on the surface of the electrode by employing the specific interaction of biotin/avidin and the conjugation of MWCNTs. Later, the electrode was incubated with antigen of mouse IgG and then reacted with the secondary antibody which was labeled by Ru-SiO2. Accordingly, through the ECL response of Ru-SiO2 and tripropylamine (TPA), a strong ECL signal was obtained and an amplification analysis of protein reaction was achieved, which led to an increase of the immunosensor sensitivity. |
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