PMQA (Zn-green), an 8-aminoquinoline-based ratiometric fluorescent sensor, demonstrates the Zn2+-induced redshift of emission (85 nm). PMQA (Zn-green) is a cell membrane-permeable probe and suitable for imaging Zn2+ in living cells[1].
After incubation with PMQA (20 μM) for 1 h, weak green fluorescence appeared, presumably caused by the probe capturing intracellular zinc from its native ligands since PMQA has high affinity for zinc[1]. The response of PMQA to Zn2+ can be reversed by N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) or EDTA[1]. When the stock solution of PMQA (0.1 mM in Tris Buffer) is kept at room temperature for a week, there is no significant loss of PMQA determined by HPLC analysis[1].
[1]. Liangwei Zhang, et al. 8-Aminoquinoline-based ratiometric zinc probe: unexpected binding mode and its application in living cells. Bioorg Med Chem Lett. 2013 Jun 15;23(12):3511-4.