Based On GC 3 N 4 Electrochemiluminescence And Signal Amplification Immunosensor Research

Immunoanalysis is one of the most important branches in bio-analysis area.It plays imcreasing roles in early warnings of diseases and clinical diagnosis.Ectrochemiluminescence?ECL?is a special form of chemiluminescence which the luminophore is excited to emit light by the species generated at the electrode surface undergoing electron-transfer reactions.ECL sensors offer the advantages of high sensitivity and good controllability,becoming the rapid developing area in the electrochemical analytical chemistry.In this thesis,three electrochemical immunosensor were developed.Details are listed below:1)A sensitivite signal-on ECL immunosensor using g-C₃N₄ as luminophoreGraphite-like carbon nitride?g-C₃N₄?was functionalized with carboxylic groups and used as an ECL luminophore,which was bonded to the second antibody as the signal tag in the immunosensor.A poly-?2-aminoterephthalic acid?film was depopsied on the surface of glassy carbon electrode by cyclic voltammetry.The primary antibody probes were immobilized on the surface of carboxylic groups modified electrode to bond the target antigen.Bounding with g-C₃N₄ conjugated second antibody,the sandwich-type immunocomplex was formed.A signal-on ECL immunosensor was obtained by measuring the ECL from g-C₃N₄ in presence of coreactant.It was shown that the g-C3 N in the immunocomplex exhibits low ECL intensity in the presence of H2O2 as a single coreactant.By using K2S2O8 as the coreactant,high ECL intensity is obtained.The ECL intensity of g-C3 N in the immunocomplex is enhanced significantly by using double coreactants of K2S2O8 + H2O2.The ECL intensity is increased with the number of cyclic voltammetry in initial ECL scanning mesurements.It was revealed that the impedance of the modified electrode is reduced in the potential scanning in the presence of K2S2O8 + H2O2,which is helpful to speed the electrons transfer from the electrode to g-C₃N₄.Under the optimal experiment conditions,the as-prepared signal-on ECL immunosensor was applied to detect carcinoembryonic antigen in a dynamic range of 0.01 pg/m L¹ng/m L with a detection limit of 3 fg/m L.2)A signal-on ECL immunosensor using Au-g-C₃N₄ as luminophoreThe nanocomposites of Au-g-C₃N₄ was prepared and used as a promising luminophore in a signal on ECL immunosensor.Au-g-C₃N₄ offers the advantages of good biocompatibility,large surface area and the high ECL intensity.The as-prepared ECL immunosensor was applied to detect alpha-fetoprotein in a dynamic range of 0.1 pg/m L¹ng/mL with a detection limit of 0.03 pg/m L.3)Signal-amplified Immunoassay Based on Biometallization of Palladium Nanoparticles and Nickel-Phosphorus EnhancermentA sensitive electrochemical immunosensor was reported with signal amplification by biometallization of Ni-P.In this strategy,the primary antibody probes were immobilized on the aminated glass surface to bond the target antigen.Bounding with alkaline phosphatase?ALP?conjugated second antibody,the sandwich-type immunocomplex was formed.The signal tag of ALP in the immunocomplex can catalyze its substrate of p-aminophenyl phosphate to produce p-aminophenol,which can reduce Pd?II?in solution to Pd nanocrystals onto the surface.The Pd nanocrystals were served as the catalyst for electroless deposition of Ni-P layer in a successive signal amplification stage.Dissolved by HNO3,the amount of Ni deposited was determination by adsorptive stripping voltammetry method to quantify the target antigen.With human IgG as the model antigen,the applicability of the method was exploited.By using a bismuth nanoparticles modified glassy carbon electrode for Ni determination,the effect of the concentrations of p-aminophenol and Pd?II?,biometallization time and temperature on the electroless deposition Ni-P were investigated and optimized.The stripping peak current of Ni was proportional to the concentration of human IgG in a dynamic range of 0.1–100 pg/mL with a detection limit of 0.03 pg/mL.