A new strategy for electrochemical immunoassay based on enzymatic silver deposition on agarose beads

A novel, sensitive electrochemical immunoassay in a homogeneously dispersed medium is described herein based on the unique features of agarose beads and the special amplified properties of biometallization. The immunochemical recognition event between human immunoglobulin G (IgG) and goat anti-human...

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Bibliographic Details
Published in:Talanta (Oxford) 2008-02, Vol.74 (5), p.1642-1648
Main Authors: Luo, Yan, Mao, Xun, Peng, Zhao-Feng, Jiang, Jian-Hui, Shen, Guo-Li, Yu, Ru-Qin
Format: Article
Language:English
Subjects:
Agarose beads
Analytical chemistry
Anodic stripping voltammetry
Antibodies
Biotinylation
Chemistry
Electrochemical methods
Electrochemistry - methods
Enzymatic silver deposition
Exact sciences and technology
Humans
Immunoassay
Immunoassay - methods
Immunoglobulin G
Metal Nanoparticles
Miscellaneous
Sepharose
Silver
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Description
Summary:A novel, sensitive electrochemical immunoassay in a homogeneously dispersed medium is described herein based on the unique features of agarose beads and the special amplified properties of biometallization. The immunochemical recognition event between human immunoglobulin G (IgG) and goat anti-human IgG antibody is chosen as the model system to demonstrate the proposed immunoassay approach. Avidin-agarose beads rapidly react with the biotinylated goat anti-human IgG antibody to form agarose beads-goat anti-human IgG conjugate (agarose bead-Ab). Agarose bead-Ab, alkaline phosphatase conjugated goat anti-human IgG antibody (ALP-Ab) and the human IgG analyte are mixed to form sandwich-type immunocomplex followed by the addition of the enzymatic silver deposition solution to deposit silver onto the surface of proteins and agarose beads. The silver deposited are dissolved and quantified by anodic stripping voltammetry. The influence of relevant experimental variables was examined and optimized. The logarithm of the anodic stripping peak current depended linearly on the logarithm of the concentration of human IgG in the range from 1 to 1000 ng/ml. A detection limit as low as 0.5 ng/ml human IgG was attained by 3 σ-rule. The R.S.D. of the approach is 9.65% for eight times determination of 10 ng/ml human IgG under same conditions. Optical microscope and TEM graphs were also utilized to characterize agarose beads and silver nanoparticles formed.
ISSN:0039-9140
1873-3573
DOI:10.1016/j.talanta.2007.10.026