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A Sensitive Electrochemical Immunosensor for α‐Fetoprotein Detection with Colloidal Gold‐Based Dentritical Enzyme Complex Amplification
Author(s) -
Liu Xueping,
Wu Huiwang,
Zheng Yue,
Wu Zaisheng,
Jiang Jianhui,
Shen Guoli,
Yu Ruqin
Publication year - 2010
Publication title -
electroanalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.574
H-Index - 128
eISSN - 1521-4109
pISSN - 1040-0397
DOI - 10.1002/elan.200904698
Subject(s) - colloidal gold , polyclonal antibodies , detection limit , chemistry , analyte , alkaline phosphatase , conjugated system , primary and secondary antibodies , monolayer , self assembled monolayer , electrochemistry , covalent bond , enzyme , electrode , chromatography , combinatorial chemistry , nanoparticle , biochemistry , antibody , nanotechnology , materials science , organic chemistry , biology , immunology , polymer
A sensitive and specific electrochemical immunosensor was developed with α‐fetoprotein (AFP) as the model analyte by using gold nanoparticle label for enzymatic catalytic amplification. A self‐assembled monolayer membrane of mercaptopropionic acid (MPA) was firstly formed on the electrode surface through gold‐sulfur interaction. Monoclonal mouse anti‐human AFP was covalently immobilized to serve as the capture antibody. In the presence of the target human AFP, gold nanoparticles coated with polyclonal rabbit anti‐human AFP were bound to the electrode via the formation of a sandwiched complex. With the introduction of goat anti‐rabbit IgG conjugated with alkaline phosphatase, the dentritical enzyme complex was formed through selective interaction of the secondary antibodies with the colloidal gold‐based primary antibody at the electrode, thus affording the possibility of signal amplification for AFP detection. Current response arising from the oxidation of enzymatic product was significantly amplified by the dentritical enzyme complex. The current signal was proportional to the concentration of AFP from 1.0 ng mL −1 to 500 ng mL −1 with a detection limit of 0.8 ng mL −1 . This system could be extended to detect other target molecules with the corresponding antibody pairs.