Dual-response detection of Ni2+ and Cu2+ ions by a pyrazolopyrimidine-based fluorescent sensor and the application of this sensor in bioimaging

Abstract

Herein, a dual-response fluorescent sensor, L, based on pyrazolopyrimidine was designed and developed for the simultaneous detection of Ni2+ and Cu2+ ions in the presence of other metal ions; the structural characterization of L was carried out by FTIR spectroscopy, NMR spectroscopy, HRMS and X-ray diffraction analysis. The sensor L effectively displayed fluorescence quenching towards the Ni2+ and Cu2+ ions with high sensitivity without interference from other metal ions. The results reveal that L binds to Ni2+ and Cu2+ in a 2:1 pattern, which matches well with the result of the Job's plot. The association constants of L with Ni2+ and Cu2+ were 3.2 × 104 M-1 and 7.57 × 104 M-1, respectively. The detection limits (DLs) are down to 8.9 nM for Ni2+ and 8.7 nM for Cu2+. The fluorescence imaging of L in T-24 cells was investigated because of the low cytotoxicity of L, indicating that L could be used to detect Ni2+ and Cu2+ in living cells.