Non-aerosol detection of explosives with a continuous flow immunosensor

Abstract

Contamination of groundwater, soil, and the marine environment by explosives is a global issue. Identification, characterization and remediation are all required for a site recognized as contaminated with 2,4,6-trinitrotoluene (TNT) or hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). For each step, a method to accurately measure the contaminant level is needed. This paper reviews some of the current methods with emphasis on a single biosensor developed in our laboratory. Current regulatory methods require samples to be sent off-site to a certified laboratory resulting in time delays up to a month. A continuous flow biosensor for detection of explosives has been developed and tested for the rapid field screening of environmental samples. The detection system is based on a displacement immunoassay in which monoclonal antibodies to (TNT) and RDX are immobilized on solid substrates, allowed to bind fluorescently labeled antigens, and then exposed to explosives in aqueous samples. Explosive compounds present in the sample displace proportional amounts of the fluorescent label, which can then be measured to determine the original TNT or RDX concentration. The system can accurately detect ppb to ppt levels of explosives in groundwater or seawater samples and in extracts of contaminated soil. The biosensor has applications in environmental monitoring at remediation sites or in the location of underwater unexploded ordnance.

Sensors—An effective approach for the detection of explosives

“…Goldman et al continued to work along with his coworkers on the detection of TNT in soil and water samples using homogeneous assay [77]. A continuous flow immunosensor has been tested for the field screening of environmental samples for the detection of explosives like TNT and RDX [78]. The system is based on displacement immunoassay in which monoclonal antibodies to TNT and RDX are immobilized on solid support and allowed to bind to the fluorescently labeled antigens and then exposed to explosives.…”

Recent Advances in Trace Explosives Detection Instrumentation

“…Shriver-Lake and colleagues have developed a continuous flow displacement immunoassay biosensor for TNT and RDX, and have used it to detect sub-ppb levels of explosives in water samples or soil extracts in less than 5 min [167]. They extended similar ideas to produce an array biosensor for simultaneous multi-analyte detection [168].…”

Photoluminescent Detection of Dissolved Underwater Trace Explosives

“…In addition to aiding environmental analysis and cleanup, underwater detection of explosive traces helps to close the security gap in marine environments, just as dry screening for explosives helps to maintain airport security. Many of the current aqueous trace explosive detection methods are constrained to laboratories, focus on low-salt groundwater, require extensive sample preparation, take a significant amount of time to complete, and are prohibitive in equipment cost [6,7,8,9]. The identification of a fast, portable, inexpensive, water-borne trace explosive detection method that could be applied to both fresh-and saltwater would serve the goals of security, forensic analysis, and environmental remediation.…”