Dual-functional chemical sensor for sensitive detection and bioimaging of Zn~(2+) and Pb~(2+) based on a water-soluble polymer

摘要

Free lead and zinc ions are toxic to living cells and environment, we develop a multi-responsive fluorescence probe based on water-soluble double hydrophilic block copolymer. The polymer sensor with Schiff moiety can sensitively, selectively and simultaneously fluorescence probe Zn~(2+) (green) and Pb~(2+) (blue) through the different fluorescence color. The linear concentration ranges for Pd~(2+) and Zn~(2+) were 0.8-10.0 μM and 0-10.0 μM with the detection limits of 0.7 μM and 0.2 μM, respectively. The probe responding to Na~+, Mn~(2+), Fe~(2+), Fe~(3+), Cu~(2+), Zn~(2+), Cd~(2+), Al~(3+), Cr~(3+), Co~(2+), Ni~(2+), Ag~+, Ca~(2+), K~+, Mg~(2+), Ba~(2+), Hg~(2+), and Pb~(2+) displays almost no significant interference with the assay process. The sensing mechanism of the PSAM probe to Pb~(2+) and Zn~(2+) was investigated by Job's plot experiment, ~1H NMR analysis and density functional theory (DFT), the results show that the nitrogen atom of CH=N and oxygen atom of OH may recognize with ions and the Job's plots for the PSAM complexes demonstrate 1:1 complexation, respectively. To achieve its application, the chemosensor is successfully applied to monitor Pd~(2+)and Zn~(2+) in tap and lake water samples, its ability to monitor free Pd~(2+) and Zn~(2+) ions in living cells or in vivo is also validated by the intracellular imaging.