Discriminative detection of neurotoxins in multi-component samples

In order to develop anew strategy for the detection and discrimination of n eurotoxins, 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 di fferent than what was expected from additive effects of single neurotoxins. Mutual interactions of various neurotoxins did lead to competition for ace tylcholinesterase (AChE) binding sites, and the overall inhibition effects were not additive but dependent on the types of chemicals present. It was p ossible to separate the effects of different inhibitors, using a combined r ecognition/discrimination strategy based on the joint action of acetylcholi nesterase and organophosphate hydrolase enzymes. The detection ranges of th ese integrated biosensors were 10(-9) to 10(-5) M for paraoxon or DFP and 5 x 10(-8) to I X 10(-5) M for carbaryl. In addition, it was possible to det ect carbaryl concentrations as low as 5 x 10(-8) M in mixed samples at conc entrations Up to 10(-5) M of paraoxon and DFP. (C) 2001 Elsevier Science B. V. All rights reserved.