Electrochemical Immunosensor Based On Polydopamine Nanocomposite

Electrochemical immunosensor were developed on the combination of immunoanalysis andelectrochemical technology, which feature rapid analysis, high sensitivity, on-line detection andease of operation as a biosensor. With the research and development of electrochemicalimmunosensor in recent years, it has become the most important and key aspect of non-labeledimmunosensor that how to fix electroactive probes without leaking such as prussian blue, toluidineblue and thionine, and further acquire sensors with high sensitivity and long lives. This paper usesa combination of different methods of electronic media Prussian blue body with carbon nanotubes,graphene oxide and magnetic iron(III) oxide nanoparticles prepare nano-composites.Using Polydopamine film coated nano-composite to immobilize electronic media，to protectand prevent leakage of electronic media, and in the membrane surface of polydopamine situreduction deposit gold nanoparticles; In order to build a series of highly sensitive and stabilityexcellent electrochemical immune sensors;Tests using transmission electron microscopy, X-raydiffraction (XRD), infrared chromatography (FT-IR) for nanocomposite morphologycharacterization performed，Transmission electron microscopy(TEM), X-ray diffraction (XRD), infrared chromatography(FT-IR), atomic force microscopy, and electrochemical techniques were used as tools forcharacterization of the electrode interface and investigated their applications in biologicalimmunity. This paper focuse on the following tasks:Contents of this experiment include the following aspects(1)Experiments first with FeCl3and K3Fe(CN)6in a mixed solution of H2O2catalytic preparePrussian blue nanoparticlesand it was surface functionalized by one-step oxidative polymerizationof dopamine in basic solution at environment friendly condition to obtain the polydopamine (Pdop)modified reduced PB nanoparticles. Then, via in situ deposition, the Au NPs deposited on thepolydopamine functionalized PB nanocomposites. Finally, antibodies were anchored on the AuNPs.Prepared gold nanoparticles/polydopamine/Prussian Blue nanocomposite particles to buildthe electrochemical immunosensor.The performance of the immunosensor had the advantages ofsimple preparation, mild experimental conditions and good biocompatibility immune modifiedelectrode and the immobilized anti-AFP was also easy.The dynamic range of the resultedimmunosensor for the detection of AFP was from0.02ng/mL to80.0ng/mL with a detection limitof0.01ng/mL (S/N=3).(2)With their unique property-superparamagnetism, magnetic nanoparticles had become attractivefor exploitation mainly in biology and medicine because they can simplify the process of proteinsimmobilization and separation. In this work. Fe3O4-PB nanoparticles were prepwered by magneticseparation method and it was surface functionalized by one-step oxidative polymerization ofdopamine in basic solution at environment friendly condition to obtain the polydopamine (Pdop) modified reduced Fe3O4-PB nanoparticles. Then, via in situ deposition, the Au NPs deposited onthe polydopamine functionalized Fe3O4-PB nanocomposites. Finally, antibodies were anchored onthe Au NPs.The preparation of the multifunctional nanoparticle (Fe3O4-PB-Dopa-Au)) wascharacterized by Fourier Transform Infrared Spectroscopy (FT-IR),X-ray diffraction (XRD),transmission electron microscopy (TEM)and the assembly of the biosensor was characterized withcyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS).The dynamic rangeof the resulted immunosensor for the detection of AFP was from0.05ng/mL to30.0ng/mL with adetection limit of0.02ng/mL (S/N=3). Moreover, this biosensor displays good selectivity,stability and reproducibility.(3)With carbon nanotubes (CNTs) large specific surface area and good electron transportproperties,In the experiments in situ deposition, making the electrical activity of the probePrussian blue (PB) nanoparticles are deposited to the surface of CNTs,it was surfacefunctionalized by one-step oxidative polymerization of dopamine in basic solution at environmentfriendly condition to obtain the polydopamine (Pdop) modified reduced CNTs-PB nanoparticles.Then, via in situ deposition, the Au NPs deposited on the polydopamine functionalized CNTs-PBnanocomposites. Finally, antibodies were anchored on the Au NPs.Preparation ofCNTs-PB-Dopa-Au nanocomposites with excellent electron transfer capability and goodbiocompatibility andIn order to build a high sensitivity non-labeled immunosensor.The dynamicrange of the resulted immunosensor for the detection of AFP was from0.01ng/mL to80.0ng/mLwith a detection limit of0.007ng/mL (S/N=3).(4)With graphene oxide (GO) excellent electronic conductivity and electrochemical activity.In theexperiments in situ deposition, making the electrical activity of the probe Prussian blue (PB)nanoparticles were deposited to the surface of GO,it was surface functionalized by one-stepoxidative polymerization of dopamine in basic solution at environment friendly condition toobtain the polydopamine (Pdop) modified reduced GO-PB nanoparticles. Then, via in situdeposition, the Au NPs deposited on the polydopamine functionalized GO-PB nanocomposites.Finally, antibodies were anchored on the Au NPs.Preparation of GO-PB-Dopa-Au nanocompositeswith excellent electron transfer capability and good biocompatibility andIn order to build a highsensitivity non-labeled immunosensor.The dynamic range of the resulted immunosensor for thedetection of AFP was from0.01ng/mL to80.0ng/mL with a detection limit of0.007ng/mL(S/N=3).