title: Amplified inhibition of the electrochemical signal of ferrocene by enzyme-functionalized graphene oxide nanoprobe for ultrasensitive immunoassay.
abstract: A nanoprobe-induced signal inhibition mechanism was designed for ultrasensitive electrochemical immunoassay at a chitosan-ferrocene (CS-Fc) based immunosensor. The nanoprobe was prepared by covalently loading signal antibody and high-content horseradish peroxidase (HRP) on the graphene oxide (GO) nanocarrier. The immunosensor was prepared through the stepwise assembly of gold nanoparticles (Au NPs) and capture antibody at a CS-Fc modified electrode. After sandwich immunoreaction, the GO-HRP nanoprobes were quantitatively captured onto the immunosensor surface and thus induced the production of a layer of insoluble film through the enzymatically catalytic reaction of the HRP labels. Both the dielectric immunocomplex formed on the immunosensor surface and the enzymatic precipitate with low electroconductivity led to the electrochemical signal decease of the Fc indicator, which was greatly amplified by the multi-enzyme signal amplification of the nanoprobe. Based on this amplified signal inhibition mechanism, a new ultrasensitive electrochemical immunoassay method was developed. Using carcinoembryonic antigen as a model analyte, this method showed a wide linear range over 5 orders of magnitude with a detection limit down to 0.54 pg/mL. Besides, the immunosensor showed good specificity, acceptable reproducibility and stability as well as satisfactory reliability for the serum sample analysis.
authors.affiliation: Hubei Collaborative Innovation Center for Rare Metal Chemistry, Hubei Key Laboratory of Pollutant Analysis & Reuse Technology, Department of Chemistry, Hubei Normal University, Huangshi 435002, PR China. Electronic address: gslai@hbnu.edu.cn.
authors.forename: Guosong
authors.initials: G
authors.lastname: Lai
authors.affiliation: Hubei Collaborative Innovation Center for Rare Metal Chemistry, Hubei Key Laboratory of Pollutant Analysis & Reuse Technology, Department of Chemistry, Hubei Normal University, Huangshi 435002, PR China.
authors.forename: Hui
authors.initials: H
authors.lastname: Cheng
authors.affiliation: Hubei Collaborative Innovation Center for Rare Metal Chemistry, Hubei Key Laboratory of Pollutant Analysis & Reuse Technology, Department of Chemistry, Hubei Normal University, Huangshi 435002, PR China.
authors.forename: Dinghong
authors.initials: D
authors.lastname: Xin
authors.affiliation: Hubei Collaborative Innovation Center for Rare Metal Chemistry, Hubei Key Laboratory of Pollutant Analysis & Reuse Technology, Department of Chemistry, Hubei Normal University, Huangshi 435002, PR China.
authors.forename: Haili
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Hubei Collaborative Innovation Center for Rare Metal Chemistry, Hubei Key Laboratory of Pollutant Analysis & Reuse Technology, Department of Chemistry, Hubei Normal University, Huangshi 435002, PR China; Department of Chemistry and Biotechnology, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn VIC 3122, Australia.
authors.forename: Aimin
authors.initials: A
authors.lastname: Yu
mesh_terms: D004563:Electrochemistry; D005296:Ferrous Compounds / Q000737:chemistry*; D006108:Graphite / Q000737:chemistry*; D006735:Horseradish Peroxidase / Q000737:chemistry*; D007118:Immunoassay / Q000379:methods*; D057230:Limit of Detection; D000075163:Metallocenes; D015335:Molecular Probes; D010087:Oxides / Q000737:chemistry
chemical_list: D005296:Ferrous Compounds; D000075163:Metallocenes; D015335:Molecular Probes; D010087:Oxides; D006108:Graphite; D006735:Horseradish Peroxidase; C004998:ferrocene
keywords: Biosensors; Electrochemical immunoassay; Horseradish peroxidase; Nanoprobe; Signal amplification