PMQA (Zn-green), an 8-aminoquinoline-based ratiometric fluorescent sensor, exhibits an 85 nm redshift in emission upon Zn 2+ induction. This cell membrane-permeable probe effectively images Zn 2+ within living cells [1].

PMQA, when incubated (20 μM) for 1 hour, exhibits weak green fluorescence attributed to its high affinity for zinc, capturing intracellular zinc from native ligands [1]. The Zn²⁺ response of PMQA can be reversed by N,N,N’,N’-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN) or EDTA [1]. PMQA stock solution (0.1 mM in Tris Buffer) shows no significant degradation when stored at room temperature for a week, as confirmed by HPLC analysis [1].