The Research Of Immunoassay Based On Heated Carbon Paste Electrode

With the development of the immunoassay, enhancing the sensitivity of immunoassay has become the common purpose of scientists. Heated carbon paste electrode (HCPE) has the following advantages, such as the simple structure of the apparatus and can improve the analytical sensitivity. Besides, the HCPE is of symmetric design and the 100kHz alternating current (ac) generated from a function generator is used to heat the electrode with no effect on the current response of the sensor, which has been testified theoretically and experimentally. In this thesis, HCPE was used in the construction of immunosensors, besides, novel immuno-lables were also used in the immunoassays, which greatly improved the sensitivity of the prepared immunosensors. The main results were summarized as follows:1.Ultrasensitive Detection of Human Interleukin 6 Using a Competitive Immunosensor Based on a Disposable Electrically Heated Screen-printed Carbon ElectrodeA facile one-step chemical reduction method was developed to prepare the polydopamine functionalized gold nanoparticle, followed by ultrasonically assembled on the surface of grapheme nanosheets. The resulting hybrid material incorporated both the high-binding capability of grapheme nanosheets, favorable biocompatibility of gold nanopaticles, and high protein affinity of polydopamine, which thus offered a promising template for biomolecule immobilization and biosensor fabrication. A novel competitive electrochemical immunoassay was then proposed by combing the RGO-AuNPs platform with quantum dots functionalized carbon nanotube labels for the sensitive detection of human interleukin 6. Enhanced sensitivity was obtained by combining the advantages of high-binding capability of grapheme nanocomposite with the QDs-based signal amplification. More importantly, an electrically heated screen-printed carbon electrode was induced in the detection procedure of the immunosensor, and further improved the sensitivity. The immonosensor exhibited a wide linear response to IL-6 ranging from 0.1 to 100pgmL-1 with a detection limit of 0.033pgmL-1. The proposed method showed good precision,acceptable stability and reproducibility, and could be used for the detection of IL-6 in real samples, which possessed promising application in clinical research.2. Electrochemical Immunosensor for Detection of MMP-9 Using Heated Carbon Paste ElectrodePPY/MWNTs modified carbon paste electrode was synthesized through electro-polymerization method. The prepared composite had porous structures and provided a promising basis for biomolecular immobilization due to its satisfactory chemical stability, good electronic conductivity and excellent biocompatibility. QDs modified PS@PDA sphere was also prepared as immuno-lables to fabricate an electrochemical immunosensor for the detection of MMP-9. HCPE was used to improve the current signal so that the sentivity of the immunosensor was greatly enhanced. The immonosensor exhibited a wide linear response to MMP-9 ranging from 0.1 to 1000pgmL-1 with a detection limit of 0.033pgmL-1...