Dual-Readout Sandwich Immunoassay for Device-Free and Highly Sensitive Anthrax Biomarker Detection

Isaac N. Larkin, Viswanadham Garimella, Gokay Yamankurt, Alexander W. Scott, Hang Xing*, Chad A. Mirkin*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

23 Scopus citations


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 (PA83). The identified antibody pair detects PA83 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 PA83 concentrations, over 3 orders of magnitude more sensitive than the colorimetric readout.

Original languageEnglish (US)
Pages (from-to)7845-7851
Number of pages7
JournalAnalytical Chemistry
Issue number11
StatePublished - Jun 2 2020

ASJC Scopus subject areas

  • Analytical Chemistry


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