Mitochondria-targeted dual-channel colorimetric and fluorescence chemosensor for detection of Sn2+ ions in aqueous solution based on aggregation-induced emission and its bioimaging applications

Abstract

Several fluorescence and colorimetric chemosensory for Sn2+ detection in an aqueous media have been reported, but applications remain limited for discriminative Sn2+ detection in live human cells and zebrafish larvae. Herein, a mitochondria-targeted Sn2+ "turn-on" colorimetric and fluorescence chemosensor, 2CTA, with an aggregation-induced emission (AIE) response was developed. The sensing of Sn2+ was enabled by a reductionenabled binding pathway, with the conversion of -C=O groups to -C-OH groups at the naphthoquinone moiety. The color changed from light maroon to milky white in a buffered aqueous solution. The chemosensor 2CTA possessed the excellent characteristics of good water solubility, fast response (less than 10 s), and high sensitivity (79 nM) and selectivity for Sn2+ over other metal ions, amino acids, and peptides. The proposed binding mechanism was experimentally verified by means of FT-IR and NMR studies. The chemosensor 2CTA was successfully employed to recognize Sn2+ in live human cells and in zebrafish larvae. In addition, a colocalization study proved that the chemosensor had the ability to target mitochondria and overlapped almost completely with MitoTracker Red. Furthermore, a bioimaging study of live cells demonstrated the discriminative detection of Sn2+ in human cancer cells and the practical applications of 2CTA in biological systems.