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Open AccessArticle

Rapid Detection of Bacillus anthracis Spores Using Immunomagnetic Separation and Amperometry

Black Ivory Biotech, Inc., P.O. Box 893128, Mililani, HI 96789, USA
Holatron Systems, LLC., 833 Ilaniwai Street, Suite 2, Honolulu, HI 96813, USA
Mike Jen Software Services, 1035 Aster Ave #2103, Sunnyvale, CA 94086, USA
Author to whom correspondence should be addressed.
Academic Editors: Sandeep Kumar Vashist, Ioannis Raptis, Panagiota Petrou and B.S. Satyanarayana
Biosensors 2016, 6(4), 61;
Received: 24 September 2016 / Revised: 9 December 2016 / Accepted: 14 December 2016 / Published: 20 December 2016
(This article belongs to the Special Issue Point-of-Care Diagnostics)
Portable detection and quantitation methods for Bacillus anthracis (anthrax) spores in pure culture or in environmental samples are lacking. Here, an amperometric immunoassay has been developed utilizing immunomagnetic separation to capture the spores and remove potential interferents from test samples followed by amperometric measurement on a field-portable instrument. Antibody-conjugated magnetic beads and antibody-conjugated glucose oxidase were used in a sandwich format for the capture and detection of target spores. Glucose oxidase activity of spore pellets was measured indirectly via amperometry by applying a bias voltage after incubation with glucose, horseradish peroxidase, and the electron mediator 2,2′-azino-bis (3-ethylbenzthiazoline-6-sulphonic acid). Target capture was mediated by polyclonal antisera, whereas monoclonal antibodies were used for signal generation. This strategy maximized sensitivity (500 target spores, 5000 cfu/mL), while also providing a good specificity for Bacillus anthracis spores. Minimal signal deviation occurs in the presence of environmental interferents including soil and modified pH conditions, demonstrating the strengths of immunomagnetic separation. The simultaneous incubation of capture and detection antibodies and rapid substrate development (5 min) result in short sample-to-signal times (less than an hour). With attributes comparable or exceeding that of ELISA and LFDs, amperometry is a low-cost, low-weight, and practical method for detecting anthrax spores in the field. View Full-Text
Keywords: bioterrorism; amperometry; anthrax spores; biodetection; immunoassay; portable assay bioterrorism; amperometry; anthrax spores; biodetection; immunoassay; portable assay
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Waller, D.F.; Hew, B.E.; Holdaway, C.; Jen, M.; Peckham, G.D. Rapid Detection of Bacillus anthracis Spores Using Immunomagnetic Separation and Amperometry. Biosensors 2016, 6, 61.

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