A novel fluorescent sensor with dual response to H2S/biothiols from flavonol derivative-grafted ethyl cellulose and its applications.

The accurate detection of hydrogen sulfide (H2S) and biothiols (cysteine, homocysteine, and glutathione) is critical due to their roles in human health and disease. Conventional micromolecular probes suffer from the ACQ effect, limiting their processability. To address this, we developed EC-NPCB, a macromolecular probe based on ethyl cellulose grafted with flavonol derivatives, which effectively suppresses ACQ effect. EC-NPCB exhibits rapid fluorescence response (2-4 min) and ultra-low detection limits (LOD) of 64.8 nM (H2S), 43.1 nM (Cys), 43.0 nM (Hcy), and 91.5 nM (GSH). Compared to its micromolecular probe MNPCB, EC-NPCB showed >10-fold improved photostability. Practical applications include real-time H2S monitoring in red wine and spoilage assessment in prawn and pork, validated against total volatile basic nitrogen (TVBN) values. Furthermore, EC-NPCB was integrated into portable test paper, enabling field-deployable food freshness detection, with significant implications for food safety and public health.