A novel double target fluorescence probe for Al/Mg detection with distinctively different responses and its applications in cell imaging.

The metal cations, Al and Mg, could affect human health and cell biological processes. Their fast and selective detection using one probe remains a challenge. A novel fluorescence probe, N'-((1-hydroxynaphthalen-2-yl)methylene)isoquinoline-3-carbohydrazide (NHMI), was developed for selectively monitoring Al and Mg. The probe NHMI showed a distinctive "turn-on" fluorescence signal towards Al and Mg (cyan for Al with 2556-folds enhancement and yellow for Mg with 88-folds enhancement), which is quite distinct from other metal cations and allows for naked-eye detection. This interesting response was attributed to the influence of PET, ESIPT process and CHEF effect, when Al or Mg chelated with NHMI. Furthermore, the fluorescence titration experiments manifested that the detection limit of probe NHMI for Al/Mg was as low as 1.20 × 10 M and 7.69 × 10 M, respectively. The formed complexes NHMI-Al and NHMI-Mg were analyzed by Job's plot, ESI-MS, H NMR and FT-IR. The coordination pockets and fluorescence mechanisms of two metal complexes were explored by density functional theory calculation. Moreover, NHMI showed low cytotoxicity and good cell permeability. Fluorescence bioimaging of Al/Mg in MCF-7 cells with NHMI indicated its potential application in biological diagnostic analysis.