Open AccessDual-Readout Sandwich Immunoassay for Device-Free and Highly Sensitive Anthrax Biomarker Detection
Author(s) -
Isaac N. Larkin,
G. Viswanadham,
Gokay Yamankurt,
Alexander W. Scott,
Hang Xing,
Chad A. Mirkin
Publication year - 2020
Publication title -
analytical chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.117
H-Index - 332
eISSN - 1520-6882
pISSN - 0003-2700
DOI - 10.1021/acs.analchem.0c01090
Subject(s) - immunoassay , chemistry , conjugate , monoclonal antibody , colloidal gold , analyte , detection limit , chromatography , nanotechnology , antibody , nanoparticle , materials science , mathematical analysis , mathematics , immunology , biology
We report a dual-readout, AuNP-based sandwich immunoassay for the device-free colorimetric and sensitive scanometric detection of disease biomarkers. An AuNP-antibody conjugate serves as a signal transduction and amplification agent by promoting the reduction and deposition of either platinum or gold onto its surface, generating corresponding colorimetric or light scattering (scanometric) signals, respectively. We apply the Pt-based colorimetric readout of this assay to the discovery of a novel monoclonal antibody (mAb) sandwich pair for the detection of an anthrax protective antigen (PA 83 ). The identified antibody pair detects PA 83 down to 1 nM in phosphate-buffered saline and 5 nM in human serum, which are physiologically relevant concentrations. Reducing gold rather than platinum onto the mAb-AuNP sandwich enables scanometric detection of subpicomolar PA 83 concentrations, over 3 orders of magnitude more sensitive than the colorimetric readout.