Selective fluorescence detection of histamine based on ligand exchange mechanism and its application to biomonitoring

We report on a novel histamine monitoring method by using a fluorescent probe, a complex between Ni(2+) and calcein, based on a ligand exchange mechanism. The fluorescence intensity of this probe, which has been reduced due to effective quenching by Ni(2+) ion, increases drastically by an addition of histamine. Furthermore, the probe shows high selectivity toward histamine among the various neurotransmitters in 0.1M phosphate buffer solution (pH 7.4). Biomonitoring studies to detect histamine released from RAW264 cells are successfully represented.