A Fluorescently Ratiometric Natural Probe for Selective Detection of Sulfur Dioxide Derivative and Host-Guest Supramolecular Regulation.

Natural sanguinarine (SG) was first used as a fluorescent probe to develop a novel ratiometric sensor for selective HSO detection. The nucleophilic addition reaction of HSO occurs at the C=N group of SG, and subsequent breakage of the conjugated π cycle leads to a decrease in the SG iminium fluorescence that is accompanied by an increase in the alkanolamine fluorescence. Therefore, a ratiometric fluorescence method with a large wavelength shift can be established for HSO detection. Furthermore, cucurbit[8]uril was used as an efficient host to encapsulate SG for an improved selectivity for HSO detection over HS. Our method benefits include little interference from other common anions and cations for HSO detection, suggesting a promising application in real sample analysis. Besides sensor development, the interaction of the natural SG with HSO was first demonstrated in this work to further get an insight into SG's pharmacology.