(25b) Non-Biological Inhibition Based Sensing (NIBS) Demonstrated for the Detection of Toxic Sulfides and Arsines

The purpose of this work is to demonstrate a new type of sensor, where inhibition of a catalytic reaction is used as a way to chemically amplify the analytical signal from an analyte molecule. By way of background, Blaedel pioneered the idea of using chemical amplification to increase the sensitivity of an analytical measurement. In this paper we have developed a new approach to chemical amplification. Instead of using the analyte as a catalyst, we use the analyte as an inhibitor for a given reaction. In detail, we find reactions A?_B that are catalyzed by a catalyst C, where C selectively binds an analyte of interest. A small change in the concentration of the analyte produces a large change in the concentrations of A and B. Consequently, the signal from the analyte is amplified. We call this technique Non-biological Inhibition Based Sensing (NIBS), because we are using the inhibition of a non-biological based catalysts as a sensing mechanism.

There are many possible catalysts that one can use; enzymes, for example, work well for chemical amplification but suffer from shelf life issues. In place of biomolecules, we have been concentrating on using materials found in Draeger tubes and other related colorimetric methods as catalysts. Draeger tubes are already reasonably selective to analytes of interest, but are not particularly sensitive. We hypothesized that if we use the chemicals in a Draeger tube or related colorimetric methods as a catalyst in a chemical amplification system, we could retain the selectivity of the colorimetric method with a much higher sensitivity. In the work here we demonstrate the success of this technique for the detection of chloroethyl methyl sulfide (CEMS) and diphenylaminechlorarsine. We find that we can enhance the sensitivity of these systems by a factor of two with no apparent loss in selectivity. This paper will focus on optimization of reaction kinetics and analysis of the inhibition reactions.