Orthogonal Detection of Nitroaromatic Explosives via Direct Voltammetry Coupled to Enzyme-Mediated Biocatalysis

This article describes a rapid and reliable electrochemical/enzymatic method of verifying the presence of nitroaromatic explosives. The new technique leverages both conventional voltammetric analysis and biocatalytic conversion of TNT. The simultaneous use of independent measurement schemes, based on two distinct processes, dramatically increases the information content and offers substantially improved reliability while minimizing the occurrence of false alarms. This has been accomplished by coupling direct voltammetric analysis with the biocatalytic conversion of the TNT substrate via nitroreductase (NR), which reduces a nitro group of TNT using NADH as an electron donor. This chemical reduction (30 s timescale) can then be observed using square-wave voltammetry by examination of the reductive and oxidative features. This novel protocol was found to be selective for TNT, not only when compared to DNT and NT, but also to other explosive species such as RDX and PETN. This unique dual-mode detection strategy for measuring TNT at a single device holds considerable promise for improving the probability of explosive detection and hence for diverse security screening applications.