Water soluble glucose-appended quinoline-benzothiazole conjugate as a selective and sensitive receptor for Cu+ ion in aqueous media and intracellular bio-imaging in live cells

Abstract

A water-soluble and biologically benign glucose-appended quinoline-benzothiazole conjugate (L) has been synthesized and characterized by various spectroscopy techniques. The recognition properties of L show selective recognition of Cu+ ion among other biological metal ions including Cu2+ ion in PBS buffer at pH 7.4. The L exhibited switch-on fluorescence enhancement after addition of Cu+ with a detection limit of 1.48 × 10‒8 M in an aqueous medium. The job’s plot confirmed the 1:1 binding ratio observed between the probe L and Cu+ ion with a association constant (Ka) of 1.46 × 105 M-1. The proposed complex binding mechanism is supported by UV-Vis, fluorescence and ESI-MS. The coordination features of complex {L+Cu+} have been delineated by DFT computational calculations. Further, the L successfully applied for the intracellular fluorescence bio-imaging of Cu+ ion in L929 living cells, suggesting that this L holds significant potential for Cu+ ion bio-imaging and disease diagnosis.