TNT Dectection Using Multiplexed Liquid-Array Displacement Immunoassays
NAVAL RESEARCH LAB WASHINGTON DC CENTER FOR BIOMOLECULAR SCIENCE AND ENGINEERING
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The presence of trace environmental contamination of soil and ground water is an ongoing concern. Historically, improper practices during the manufacture and storage of explosives, such as 2,4,6-trinitrotoluene TNT, were the primary causes. Now, the need for trace detection of explosives is further heightened by current homeland security concerns. Required are easy-to-use, sensitive, and fast methods to facilitate the detection and quantification of these contaminants, whether to monitor remediation or provide surveillance. Biosensors have been found effective for solution-phase detection of environmental contaminants, with NRL pioneering the use of flow displacement immunoassays. Our work utilized the Luminex100 a commercial flow cytometer, which can perform highly multiplexed assays by discriminating between up to 100 different bead sets, each of which can be used to test for a different target. While the Luminex100 has been shown to be a highly effective biosensor for sandwich or competitive immunoassays, the goal of this project was to demonstrate for the first time a displacement immunoassay on this platform, and to test its suitability for TNT detection in the marine environment. We evaluated four different TNT monoclonal antibodies, two recombinant TNT antibodies, and a control antibody simultaneously for the rapid detection of TNT and other nitroaromatics. TNT was detected at 0.1 ppb and could be quantified over the range of 1 ppb to 10 ppm. In addition, the assay was shown to be effective in various matrixes such as lake water, sea water, and soil extracts. This ability to function in the maritime environment is critical for Naval applications, such as trace detection of explosive materials onboard interdicted vessels, anti-mine operations, or detection of unexploded ordinance.
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