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

Abstract

Natural sanguinarine (SG) was first used as a fluorescent probe to develop a novel ratiometric sensor for selective HSO₃⁻ detection. The nucleophilic addition reaction of HSO₃⁻ 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 HSO₃⁻ detection. Furthermore, cucurbit[8]uril was used as an efficient host to encapsulate SG for an improved selectivity for HSO₃⁻ detection over H₂S. Our method benefits include little interference from other common anions and cations for HSO₃⁻ detection, suggesting a promising application in real sample analysis. Besides sensor development, the interaction of the natural SG with HSO₃⁻ was first demonstrated in this work to further get an insight into SG’s pharmacology.