The fluorescence intensity of acetylcholinesterase (AChE) bound thioflavin-T (ThT) is found to decrease regularly in presence of cholinergic inhibitors. The quenching phenomenon is not consistent with typical Stern-Volmer mechanism and can be explained on the basis of dynamic replacement of the probe from AChE gorge into the bulk aqueous medium. The resulting modulation in steady state intensity and/or time-dependent fluorescence depolarization forms the basis of a molecular switch between ThT and inhibitors, which can be correlated with AChE inhibition activity of the drugs. (C) 2016 Elsevier B.V. All rights reserved.