A new fluorometric method for the detection of the neurotransmitter acetylcholine in water using a dansylcholine complex with p-sulfonated calix[8]arene

A new method for the fluorometric detection of the neurotransmitter acetylcholine (ACh) in water is presented. Use of the fluorescence of dansylcholine (DANCh) bound to p-sulfonated calix[ 8] arene affords a new fluorometric method for the detection of ACh (>10(-4) M) in aqueous solution (pH = 6.9). The fluorescence intensity of DANCh in aqueous solution was enhanced 1.8 fold after the complexation with p-sulfonated calix[8] arene. The addition of ACh to the aqueous solution of the DANCh-calix[8]arene complex significantly decreased the fluorescence intensity, which results from the replacement of DANCh in the complex with ACh. The effects of other synaptic neurotransmitters on the fluorescence of the DANCh complex were examined for dopamine, histamine, ATP, GABA, glycine, L-glutamic acid, and L-aspartic acid. Among the neurotransmitters studied, ACh was most effective in changing the fluorescence of the DANCh complex. Possible application of the DANCh complex dye for the detection of ACh in biological systems is discussed.