The Electrocatalysis Of Bimetallic Nanoparticles Modified Electrode And Investigation Of A Novel Reagentless Electrochemical Immunosensor

Nanoparticles have excellent properties in electricity, magnetism, optics and predominant biocompatibility, especially core-shell nanoparticles which exert crucial functions in the fields of biochemical immunoanalysis, electrochemistry, material, electron, biomedicine and clinical diagnosis. In this paper, Sole metallic and bimetallic nanoparticles modified electrode were prepared and their applications in bioanalysis and biosensor domain were discussed. The major work consists of two parts:In the first part of this paper, firstly, Au core-Pt shell bimetallic nanoparticles (Au@Pt) was prepared by chemical reaction and was modified to the surface of gold electrode by self-assembly, then the Au@Pt/PVP/Au modified electrode(CME) was obtained. Contemporary, the electrochemical behavior and electrocatalysis abilities of Au@Pt/PVP/Au CME were invesitigated, moreover, it was studied and compared electrocatalytic properties of Au@Pt/PVP/Au CME toward formaldehyde(HCHO) in neutral and acid medium. The study showed that Au@Pt/PVP/Au CME exhibits favourable electrocatalysis performance toward HCHO in neutral and acid solution. The electrocatalytic performance was superior to sole gold nanoparticles(Au-NPs) or platium nanoparticles(Pt-NPs) modified electrode. In acid solution, it has good linear range of HCHO with concentration from 10μg/g to 400μg/g with a detection limit of 4μg/g; in neutral solution, its linear range was from 2μg/g to 760μg/g with a detection limit of 1μg/g.Secondly, Au@Pt core-shell nanoparticles with different scales were obtained by direct electrodeposition and proportion alteration of Au and Pt. The electrochemical behavior and electrocatalytic capability of Au@Pt modified electrode which was made of different material proportion were also studied, electrocatalytic performance toward NO2^-and DA on this modified electrode in neutral medium was investigated and compared . There was also good linear range of NO₂^- and DA with concentration from 5×10^-5-5.8×10^-3mol/L,2-72μg/g with a detection limit of 2×10^-5mol/L, 1μg/g respectively. Meanwhile, this modified electrode can quantificationally detect NO2" and DA. The results illuminated that there was mutual consensus about electrocatalytic function between Au-NPs and Pt-NPs, and bimetallic nanoparticles were in favor of improving the electrocatalysis capability of the electrode.In the second part of this paper, a novel reagentless electrochemical immunosensor was obtained, which was based on NGs/TMB/Nafion-film by entrapping 3,3'5,5-Tetramethylbenzidine (TMB) and NGs on the electrode surface by self-assembly. The prepared immunosensor was characted by the Cyclic voltammograms (CVs) and Electrochemical impedance spectroscopy (EIS) and the reaction instance between the goat anti-mouse antibody(anti-MIgG) immobilized on the electrode surface and mouse antigen(MIgG) and its reaction condition such as pH value, incubation time, incubation temperature were also investigated. The results showed that the immunosensor exhibits excellent electrochemical response in pH=5.0 acetate buffer solution, NGs has two functions, on the one hand, it accelerated the conduct of electron; on the other hand, it enhanced the mount of anti-MIgG immobilized, under the greatest condition: pH=5.0, the incubation time was about 30min, 37℃was needed for incubation tempreture, the CVs of this electrochemical immunoelectrode showed that it had sensitive response for MIgG and exhibited wide linear range, In the range of MIgG concentration from 20 to 120ng/mL, there was a good linear response and with a detection limit of several ng/mL. This modified electrode possessed excellent selectivity, high stability and nicer rebirth capability. This kind of reagentless electrochemical immunosensor held many virtue such as simple fature, cheap, high sensitivity and carry through fast on-line detection.