A sulfonamidoquinoline-derived Zn2+ fluorescent sensor with 1:1 Zn2+ binding stoichiometry

The integration of bis(pyridin-2-ylmethyl)amine (BPA) with 8-sulfonamidoquinoline (SQ) resulted in a new fluorescent Zn2+ sensor of 1:1 binding stoichiometry. The synergic Zn2+ coordination of BPA and SQ motifs provides the sensor the advantage over TSQ and its analogues in discriminating mobile Zn2+ from the bound Zn2+ of unoccupied coordination sites in living systems. Its pH-independent Zn2+-enhanced emission in physiological condition and cell permeability make it an effective intracellular Zn2+ imaging agent. This sensor profits also from its confirmed Golgi-preferential affinity, and its pH-independent Zn2+ response in physiological pH range provides it the advantages over other xanthenone-based sensors.