Development of a lateral flow assay as a point-of-care diagnostic device for the detection of poisoning with cholinesterase-inhibiting compounds.

Organophosphorus (OP) nerve agent and pesticide exposure pose a threat to both the armed forces and civilians. To support clinical decision-making, erythrocyte acetylcholinesterase and plasma butyrylcholinesterase activity in whole blood can be evaluated. Currently, laboratory diagnosis is time-consuming and not broadly available. Thus, we developed in a proof-of-concept study a lateral flow assay for the rapid, on-site diagnosis of an OP poisoning. The lateral flow assay is based on the colorimetric Ellman reaction and detects total cholinesterase activity in whole blood through a clear color change at the test strip, allowing for visual evaluation. OP poisoning is indicated when no color change occurs on the absorbance pad of the test strip, while normal cholinesterase activity is indicated by a pronounced yellow color change. A parallel visual control strip serves as a reference; its yellow color intensity is calibrated to represent uninhibited cholinesterase activity, helping users interpret the results. Furthermore, the reproducibility and sensitivity of the lateral flow assay were assessed using the persistent organophosphate nerve agent VX and the organophosphate pesticide paraoxon-ethyl. The findings indicated high reproducibility and adequate sensitivity.