Development of a Ratiometric Fluorescent Probe with Zero Cross-Talk for the Detection of SO₂ Derivatives in Foods and Live Cells

Abstract

Sulfur dioxide (SO2) derivatives are extensively utilized as both a preservative for foods and an active gaseous signal molecule in various physiological and pathological processes, but their excessive intake would bring harmful effects on human health; so, the determination of SO2 derivatives is of great importance. Herein, we developed a ratiometric fluorescent probe named 2-(2′-hydroxyphenyl)­benzothiazole-3-ethyl-1,1,2-trimethyl-1H-benzo­[e]­indolium (HBT-EMBI) by introducing a hemicyanine unit of EMBI to an HBT group for the detection of SO2 derivatives via an excited-state intramolecular proton transfer (ESIPT) and intramolecular charge transfer (ICT) effects. The probe displays some advantages, such as a colorimetric change from purple to colorless, a ratiometric fluorescence with zero cross-talk, and a remarkably large emission shift (Δλ = 164 nm) under a single-wavelength excitation. Accordingly, the probe HBT-EMBI has been successfully employed for the colorimetric and ratiometric determination of SO2 derivatives in real food samples and the quantitative visualization of SO2 derivative variations in HepG2 cells.

A mitochondria-specific NIR fluorescence probe for dual-detection of sulfur dioxide and viscosity in living cells and mice

“…The results suggest that the addition reaction of HSO 3 − /SO 3 2− disrupted the conjugation and the intramolecular charge transfer (ICT) process between diethylaminocoumarin and benzothiazolium salt moieties. 20,21,39 Additionally, a well-established linear relationship ( R 2 = 0.9931) between the fluorescence intensity ratio at 500 nm to that at 690 nm and the concentration of HSO 3 − /SO 3 2− was observed within the range of 0 to 60 μM (Fig. 1E).…”

“…20 The detection limit of CMBT for SO 2 is calculated to be 0.17 μM. 39 These results indicated that the probe CMBT has a longer emission wavelength and excellent sensitivity to SO 2 compared to the reported literature. 8,12,13,15,18…”

“…The evaluation of selectivity and anti-interference is pivotal in determining the practical applicability of the probe for detecting SO 2 under complex physiological conditions. 11,39 The selectivity of probe CMBT towards SO 2 was determined using UV-Vis and fluorescence emission spectra in PBS buffer (pH = 7.4, 10 mM). Probe CMBT (10 μM) was treated with various analytes (100 μM) respectively, such as Cys, GSH, Hcy, NO 3 − , AcO − , S 2 − , CO 3 2− , Cl − , I − , ClO − , H 2 O 2 , NO 2 − , ClO 4 − and SO 2 .…”

“…36–38 For instance, Liu and co-workers developed a ratiometric fluorescent probe for the detection of SO 2 derivatives, showing promise in real food samples and the quantitative detection of SO 2 derivative changes in HepG2 cells. 39 Tang and co-workers constructed a series of near-infrared fluorescent probes based on dihydroxanthene for monitoring variations of mitochondrial viscosity in live cells and mice. 40 Nevertheless, most of these probes suffer from issues such as poor water solubility, longer response time, and shorter emission wavelength.…”