Preparation And Application Of Electrochemical Immunosensor Based On Poly(Thionine) Film Electrode

Electrochemical immunosensors have become a more and more popular analytical technique owing to its simple instrumentation, high sensitivity, wide dynamic range, reproducibility, simplicity and rapidity. In the paper, the glutaraldehyde or nano-Au was used to attach protein on the poly(thionine) film electrode, fabricating three novel electrochemical immunosensors based on the electrochemical and photoelectrochemical effect of the modified electrode. And two proteins were detected with the prepared immunosensors. The more detailed content is as follows:1. Preparation and application of a-fetoprotein immunosensor based on the poly (thionine) film electrodeAn elcctrochemicalα-fetoprotein immunosensor was constructed by using an electropolymerized thionine film on a platinum electrode. The amino groups of poly(thionine) was used to covalently attach protein probes via the aid of glutaraldehyde cross-linking, and enzyme-earmarked antibody catalyzed H2O2 to oxidize poly(thionine) when immunoreaction. The electrochemical response was recorded as the detected signal. Under the optimized conditions, the immunosensor showed a specific response to a-fetoprotein in the range from 5.00 to 200 ng·mL-1 with a detection limit of 3.70 ng·mL-1. The relative standard deviation was under 3.62% (n=5) for the determination of samples. The immunosensor is satisfactory to the determination of human serum samples, and shows high stability and sensitivity.2. Preparation of photoelectrochemical immunosensor based on poly(thionine) film electrodeThe aloha-fetal protein (AFP) and carcino enbryonic antigen (CEA) photoelectrochemical immunosensor was prepared based on poly(thionine) film electrode. On the basis of poly(thionine) film electrode, the gold nanoparticles were used to immobilize protein probes The nano-Au can adsorb antibodies because of its large specific surface areas and good biocompatibility. Moreover, the ferrocene was used as an electron donor in the photoelectrochemical reaction. The modified process was electrochemically monitored by cyclic voltammetry and photocurrent response. The factors of experiment were studied in detail. The photoelectrochemical immunosensor is non marker and convenient for its preparation. And this photoelectrochemical reaction can be employed as a new method for the determination of proteins.3. The applications of photoelectrochemical immunosensorThe immunoassay of AFP and CEA were fulfilled by using photoelectrochemical immunosensor. Under the optimized conditions, the immunosensor showed a specific response to AFP with the range from 5.00 to 150 ng·mL-1 and a detection limit of 2.67 ng·mL-1. And in terms of CEA, the linear range was 5.00 ~ 80.0 ng·mL-1 and the detection limit was 3.26 ng·mL-1.