Bithiophene-based fluorescent sensor for highly sensitive and ultrarapid detection of Hg2+ in water, seafood, urine and live cells

Abstract

Using Hg²⁺-promoted deprotection reaction, we have developed a new fluorescent turn-on sensor 2TS based on bithiophene fluorophore for Hg²⁺ detection. The sensing mechanism of 2TS towards Hg²⁺ was strongly proved by ¹H NMR, FTIR, HRMS, UV-vis and fluorescence spectra. Remarkly, 2TS towards Hg²⁺ in 100% aqueous solution shows high sensitivity with a low detection limit of 19 nM, superior selectivity and ultra-rapid response of 20 s during a wide sensing pH range from 4 to 10. Taking advantage of the excellent properties, the low-cost sensor 2TS-based filter paper/TLC test strips were fabricated for visual, immediate and quantitative detection of Hg²⁺ in water, proving its applicability towards sensitive in-situ and on-site detection. Meanwhile, 2TS showed high analytical performance for Hg²⁺ detection in water, seafood as well as human urine samples. Moreover, thanks to the good water solubility, negligible cytotoxicity, good biocompatibility and cell-membrane permeability, 2TS was further applied to effectively image Hg²⁺ in live cells. Furthermore, the developed sensor 2TS acted as good fluorescent display material for Hg²⁺ with obvious color change.

Keywords: Bithiophene; Cell image; Fluorescent display material; Fluorescent sensor; Hg(2+).