High-performance near-infrared fluorescence probe for fast and specific visualization of harmful sulfite in food, living cells, and zebrafish

Excessive sulfite is harmful to human health. To monitor the sulfite level in food, living cells, and organisms, we herein present a high-performance near-infrared (NIR) fluorescent probe DCQN that exhibits chromogenic and NIR fluorescence turn-on response towards sulfite with a rapid response time of 4.5 s, unique specificity, a low detection limit of 24 nM, and a large Stokes shift. DCQN was used for the facile and accurate determination of the sulfite level in real food with high sensitivity and good recoveries (93-105%). In particular, the sulfite present in food samples can be in situ visually detected by DCQN in terms of chromogenic reaction along with fluorescence turn-on indicator. Moreover, DCQN was incorporated into agar hydrogel to serve as a convenient, cheap and portable device for the fast and visual on-site detection of sulfite in food. Furthermore, DCQN was used to achieve in situ tracking and imaging of sulfite in MCF-7 cells and zebrafish with a high contrast ratio and high sensitivity.