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Impedance Detection of 3‐Phenoxybenzoic Acid with a Noncompetitive Two‐site Phage Anti‐immunocomplex Assay
Author(s) -
Pali Madhavi,
Bever Candace R. S.,
Vasylieva Natalia,
Hammock Bruce D.,
Suni Ian I.
Publication year - 2018
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.201800457
Subject(s) - detection limit , immunoassay , polyclonal antibodies , analyte , bacteriophage , chromatography , dielectric spectroscopy , chemistry , materials science , antibody , electrode , electrochemistry , biology , escherichia coli , biochemistry , gene , immunology
Both direct and non‐competitive two‐site (sandwich) immunoassays are reported for 3‐phenoxybenzoic acid (3‐PBA) utilizing signal transduction by electrochemical impedance spectroscopy (EIS), and the sandwich immunoassay reduces the detection limit for this small molecule analyte by ∼70×. The direct EIS immunoassay utilizes a polyclonal antibody to 3PBA for biomolecular recognition, while the sandwich EIS immunoassay utilizes in addition a previously reported antiimmunocomplex M13 bacteriophage clone. For both immunoassays, the polyclonal antibody film is immobilized atop an Au electrode by amide bond formation. The direct EIS immunoassay exhibits a 3‐PBA sensitivity of 5.4×10 4 kΩ cm 2 M 1 , and a detection limit of 2.5×10 −4 M (54 μg/ml), while the sandwich EIS immunoassay exhibits a 3PBA sensitivity of 4.2×10 6 kΩ cm 2 M −1 , and a detection limit of 3.4×10 −6 M (0.74 μg/ml). For the sandwich EIS immunoassay, a constant excess (80×10 9 PFU/ml) of bacteriophage is maintained during all experiments. This is the first report of a bacteriophage‐assisted sandwich EIS assay.