Carbon dots-embedded fluorescent molecularly imprinted photonic crystals hydrogel strip for accurate and selective detection of rutin in Sophora japonica products

This study aimed to develop a fluorescent molecularly imprinted photonic crystals hydrogel (FMIPH) strip based on carbon dots (CDs) and inverse opal photonic crystals (PCs) for the detection of the active ingredient rutin in Sophora japonica products. The FMIPH-based sensing system was constructed using rutin as template molecules, 4-vinylpyridine as functional monomers, ethylene glycol dimethacrylate as the cross-linker, and inverse opal PCs with three-dimensional macroporous structure as the skeleton. The prepared CDs, SiO(2 )microspheres, PCs model, and FMIPH were characterized in detail, and the prepared CDs-embedded FMIPH strip exhibited stable and sensitive reproducible fluorescence response, and selective recognition capability to rutin. The linear fluorescence response of CDs-embedded FMIPH to rutin was obtained in the concentration range of 2.5-40 mu g mL(-1) (R-2 = 0.9876) with a limit of detection of 2.3 mu g mL(-1 )and a limit of quantitation of 7.2 mu g mL(-1). The CDs-embedded FMIPH strip obtained satisfying recoveries (81.7-95.6 %) with a relative standard deviation less than 3.1 % (n = 3) in spiked samples, having a good agreement with the results from high-performance liquid chromatography (R-2 = 0.9945). This portable strip could be used for rapid identification and quantitative detection of rutin in complex matrices, showing broad prospects in the quality evaluation and grading of functional foods.