A Chemically Synthesized Capture Agent Enables the Selective, Sensitive, and Robust Electrochemical Detection of Anthrax Protective Antigen

Report No. ARL-RP-0502
Authors: Blake Farrow, Sung A Hong, Errika Romero, Bert Lai, Matthew, B Coppock, Kaycie, M Deyle, Amethist, S Finch, Dimitra, N Stratis-Cullum, Heather Agnew, Sung Yang, and James, R Heath
Date/Pages: August 2014; 14 pages
Abstract: We report on a robust and sensitive approach for detecting protective antigen (PA) exotoxin from Bacillus anthracis in complex media. A peptide-based capture agent against PA was developed by improving a bacteria display-developed peptide into a highly selective biligand through in situ click screening against a large, chemically synthesized peptide library. This biligand was coupled with an electrochemical enzyme-linked immunosorbent assay utilizing nanostructured gold electrodes. The resultant assay yielded a limit of detection of PA of 170 pg/mL (2.1 pM) in buffer, with minimal sensitivity reduction in 1% serum. The powdered capture agent could be stably stored for several days at 65 °C, and the full electrochemical biosensor showed no loss of performance after extended storage at 40 °C. The engineered stability and specificity of this assay should be extendable to other cases in which biomolecular detection in demanding environments is required.
Distribution: Approved for public release
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Last Update / Reviewed: August 1, 2014