Electrochemical Immunosensing Of Two Proteins

Electrochemical biosensors,developed by the biorecognition or biocatalysis principle and the electrochemical signal output and amplification technologies,have the advantages of high sensitivity,low detection limit,good selectivity,simple operation and low cost,and are of important research and application value in the fields of food safety,biomedicine and environmental analysis.Because of the intrinsically high specificity of biorecognition and biocatalysis,improving the sensitivities of biosensors has always been the core scientific problem.In this thesis,after a brief review on the recent progress of immunoelectrochemical sensor and its signal amplification,we studied the sensitive electrochemical sensing of galectin-3(Gal-3)and nitrogen-terminal pro-B-type natriuretic peptide(NT-pro BNP)through biological affinity reactions,biolabeling and electrochemical signal amplification.The main contents are as follows.1.A high-performance dual-signal sandwich-type electrochemical immunosensor for Gal-3 was constructed by the covalent immobilization of the first antibody on electroreduced carboxyl graphene and the adsorption immobilization of the second antibody in aminated mesoporous silica nanoparticles labeled with methylene blue(MB)and gold nanoparticles(Au NPs).The relevant electrodes and materials were characterized by electrochemistry,quartz crystal microbalance,scanning electron microscopy and energy dispersive spectroscopy.Under optimized conditions,the MB-based in-situ microdroplet voltammetry showed a linear detection range(LDR)of Gal-3 from 50 fg m L-1 to 500 ng m L-1,with a limit of detection(LOD,S/N=3)of 2.0 fg m L-1;and the Au NPs-based in-situ microdroplet anodic stripping voltammetry showed an LDR of Gal-3 from 0.5 fg m L-1 to 500 ng m L-1,with a LOD(S/N=3)of 0.17 fg m L-1.The detection of clinical serum samples by our method returned satisfactory results.This research may help the high-sensitivity voltammetric detection of both metal nanomaterials and other electroactive biolabels for wider bioanalysis applications.2.Immunoassay of nitrogen-terminal pro-B-type natriuretic peptide(NT-pro BNP)was conducted using Cu2+-1,3,5-benzenetricarboxylic acid metal-organic frameworks(HKUST-1 MOFs)as the secondary antibody label,and in situ microliter-droplet anodic stripping voltammetry detection of Cu2+ in 0.1 M HNO3 + 1 M Na Cl directly on the glassy carbon immunoelectrode.Electrochemical methods,quartz crystal microbalance,scanning electron microscopy and energy dispersive spectroscopy were employed for material and electrode characterizations.Under optimized conditions,the limit of detection(S/N=3)was 0.33 fg m L-1,and the analysis of NT-pro BNP in clinical serum samples returned good results.