Badges of Immobilized Enzymes: Detection of Chemical Warfare Agents

Rapid detection of chemical warfare agents (CWAs) in all of its forms including gas and liquid is of paramount importance to protect the warfighter or first responders in homeland defense. CWAs such as OPs and vesicants pose serious threats because these agents can be ingested with contaminated food or rapidly penetrate skin. We reported that polyurethane immobilized cholinesterases (acetyl and butyryl) yielded a product with similar enzyme activity as soluble enzyme. While enzyme sensors have the advantage of selectivity, sensitivity and, most important, specificity, ChEs are particularly ideal enzymes for rapid detection of OPs because they possess some of the fastest turnover rates known for any enzyme, and are the most sensitive targets for CWAs including GA (tabun), GB (sarin, the agent used by the terrorist group in Japan in 1995), GD (soman), and vX. We also reported that immobilized cholinesterase biosensors exhibited remarkable stability suitable for detection of OPs in both air and water, and stability to harsh environmental conditions because the immobilized enzymes do not leach from the polyurethane support. We now describe two improvements over current OP detecting kits. (1) Immobilized enzyme badges are being designed as a field system capable of identifying the type of OP present. This will aid in treatment. (2) A coupled enzyme reaction also provides rapid colorimetric or electrochemical indication of vesicants (HD). Therefore, one badge detects two classes of CWAs. With the constant threat of chemical warfare or terrorist acts, the development of alternative means to rapidly identity CWAs is critical.