"Switch-on" fluorescence sensing platform based on porphyrin metal-organic frameworks for rapid and specific detection of zinc ion.

Abstract

Zinc ion (Zn2+) is a necessary transition metal ion in the human body and plays a vital role in biological systems. Therefore, it is meaningful for rapid, sensitive, and specific detection of Zn2+. Herein, a "switch-on" fluorescence sensing platform for the detection of Zn2+ was successfully established. In this work, we report an optical nanoprobe with amino functional groups based on porphyrin metal-organic frameworks (PCN-NH2) through a simple treatment method. The modification of the salicylaldehyde (SA) through the C=N acts as a quencher of PCN-NH2 and the ligand of Zn2+ can effectively inhibit the fluorescence emission of PCN-NH2. The complex of porphyrin-based metal-organic framework and salicylaldehyde (PCN/SA) acts as the fluorescence sensing probe. The presence of Zn2+ results in the new emission peak at 448 nm due to the formation of a complex between Zn2+ and SA. The corresponding fluorescence signal changes were used to accurately detect the concentration of Zn2+. The fluorescence sensing platform shows advantages, including rapid response, high sensitivity, and excellent specificity with a linear detection range of Zn2+ between 0.1 and 250 μM, and a low detection limit (LOD) of 0.07 μM. And the feasibility of the method was verified for the quantification of Zn2+ in cell lysate, environmental water, and plasma.