Turn on ESIPT based chemosensor for histidine: Application in urine analysis and live cell imaging

Abstract A vitamin B 6 cofactor containing excited-state intramolecular proton transfer (ESIPT) based fluorescent sensor [Cu(LH 2 )Cl 2 ]·2H 2 O [LH 2 is pyridoxal-semicarbazide Schiff base] is used as a selective “naked-eye” fluorescent sensor of l -histidine at pH 7.4 in aqueous media via the ligand displacement approach. Uv-Vis spectrophotometry and cyclic voltammetry can also be used to detect l -histidine by the Cu(II)-complex. The DFT calculation also supports the sensing phenomena. The fluorescence imaging studies indicated that the Cu(II)-complex can be applied to visualize the intracellular histidine in living cells. Our chemosensor can also be used for quantitative determination of histidine in urine. It acts as a helpful tool for physiological and pathological estimation of histidine. It also shows high efficiency in ‘dip-stick’ method.