A fluorogenic probe based on chelation-hydrolysis-enhancement mechanism for visualizing Zn in Parkinson's disease models.

Developing efficient methods for the real-time detection of Zn levels in biological systems is highly relevant to improving our understanding of the role of Zn in the progression of Parkinson's disease (PD). In this work, a novel Schiff base based Zn fluorescent probe (ZP) was designed, synthesized and systematically investigated. A significant turn-on effect on ZP upon the addition of Zn was observed, accompanied by a blue-shift of the fluorescence spectra. ZP is sensitive to Zn and has excellent selectivity against various biologically relevant cations, anions and amino acids. The sensing mechanism of ZP was studied by H NMR, MS, single crystal X-ray diffraction and theoretical calculations. The results showed that the response of ZP to Zn was based on the chelation-hydrolysis-enhancement process. Upon bonding, Zn hydrolyzes the Schiff base to an aldehyde precursor, the resulting aldehyde further coordinates to Zn to form a more stable heterobimetallic complex leading to the emission enhancement and blue-shift. ZP was applied to imaging exogenous/endogenous Zn in live HeLa cells. Furthermore, we successfully measured the Zn levels using in vitro PD models, which provided a visualization method to better understand the relationship between Zn levels and PD development.