SBIR-STTR Award

The long term objective is to develop a rapid "nerve agent" dosimeter detection system as simple, fieldable and rugged as a piece of wet, chemically impregnated cloth. It would have the sensitivity to detect less than 1 ng/m(3) of nerve agent in the field and the high specificity to agent physiological function inherent to enzyme inhibition. Each dosimeter would weight less than 1/4 oz. And cost less than $0.50. This long term objective will be accomplished by our unique method of splitting detection into two steps, that can each be independently investigated. The first step is exposure of the dosimeter (an enzyme impregnated wick) to the inhibiting agent. The second step is read-out after applying a "developing" chemical to the dosimeter. This "developer" fluoresces on contact with uninhibited enzyme, indicating the amount of agent to which the dosimeter was exposed. The fluorescence is then read-out with a rugged, inexpensive pocket fluorimeter. The specific objective of phase i is to investigate the performance, stability and reproducibility of the chemistry of the second stage of the proposed method.

We propose to develop a system consisting of a small, cheap, disposable dosimeter badge, and an inexpensive portable fluorimeter to be used together for detection of nerve agent in the field. The detection is based on acetylcholinesterase inhibition giving the system high functional specificity. Also, our separation of detection into two steps eliminates flow or mixing of reagents and enables us to incorporate a reference to compensate for reagent and badge variations. Other advantages of our method over existing techniques are: 1. Our indicator is fluorescent rather than colorimetric because fluorimetry is inherently more sensitive than colorimetry. The projected sensitivity of our integrating badge meets the army's sensitivity goal (10(-5) mg/m(3)) in only one second of integration time and sensitivity increases linearly with time. 2. Our use of an inexpensive disposable badge allows widespread unattended use (e.g. On perimeters). 3. Our readout requires no subjective interpretation as do many colorimetric tests. The phase ii effort will include: synthesis of substrate 1-methyl-7-acetoxy-quinolinium iodide, construction of consumable prototype badge readout chamber, demonstration of badge/readout chamber with simulant and the design and construction of an inexpensive fieldable fluorimeter.