Discriminative detection of neurotoxins in multi-component samples

In order to develop a new strategy for the detection and discrimination of neurotoxins, the competing anti-acetylcholinesterase activities of mixtures of different neurotoxins were investigated. The combined inhibition effects in mixtures of organophosphates and carbamates (such as paraoxon/carbaryl, diisopropyl fluorophosphate (DFP)/carbaryl, paraoxon/DFP/carbaryl) were different than what was expected from additive effects of single neurotoxins. Mutual interactions of various neurotoxins did lead to competition for acetylcholinesterase (AChE) binding sites, and the overall inhibition effects were not additive but dependent on the types of chemicals present. It was possible to separate the effects of different inhibitors, using a combined recognition/discrimination strategy based on the joint action of acetylcholinesterase and organophosphate hydrolase enzymes. The detection ranges of these integrated biosensors were 10−9 to 10−5 M for paraoxon or DFP, and 5×10−8 to 1×10−5 M for carbaryl. In addition, it was possible to detect carbaryl concentrations as low as 5×10−8 M in mixed samples at concentrations up to 10−5 M of paraoxon and DFP. © 2001 Elsevier Science B.V. All rights reserved.