The Construction And Application Of New Dual-mode Immunosensors Based On Various Nanomaterials

Dual-mode immunosensor is an analytic method which combined the immune recognition system and the dual-mode detection technologies. In the established processes, two or more probes were assembled in this immunosensor to produce various signals in same or different detection conditions. Dual-mode immuosensor not only has the advantages of dual-mode sensor, such as high accuracy, large signal-throughout and sample saving, but also combines the features of immune analysis. Electrochemistry and photoelectrochemistry have the characters of high sensitivity, low cost and easy miniature and so on. Their combination could make in-situ, in-vivo, real-time, on-line detection more easy, and also benefited to widen the analytic range of analyte. In this thesis, we developed three new electrochemical-photoelectrochemical immunosensing systems which was sensitized by nanomaterials and could achieve the high sensitve quantifitional detection of diverse tumor markers. These immunosensing strategies would benefit the exploration and applications of electric dual-mode immmunosensor.In first chapter, a new dual mode competitive immunosensing platform for sensitive determination of a-fetoprotein (AFP) combined photoelectrochemical and electrochemical methods was designed on graphite carbon nitride and reduced graphene oxide (g-CN/rGO) conjugate support. In second chapter, a new enzyme-free all-in-one bioprobe, consisted of hematin decorated magnetic NiCo2O4 superstructure (ATS-MNS-Hb), was designed for ultrasensitive photoelectrochemical and electrochemical dual-readout immunosensing of carcinoembryonic antigen (CEA) on carbon nanohorns (CNH) support. This immunosensor possessed high sensitivity and stability in the analytic processes of CEA. The combination of dual-mode immunosensor and logic system could achieve the intelligent diagnosis of disease. In third chapter, we exposed for the first time the application of p-type semiconductor, silver iodide-chitosan (AgI-CS) nanoparticle as peroxidase mimetic to catalyze bioprecipitation reaction for signal-amplification of photocathodic immunosensor for ultrasensitive detection of human interleukin-6 (IL-6). This work not only developed the dual-mode immunosensor, but also provided the new strategy for the signal-amplification of photocathodic immunosensor.