Reaserch On Fluorescence Sensing Strategies Based On Rhodamine And Carbon Dots For The Detection Of Lead Ions And Rutin In Food

Lead ion(Pb²⁺)has highly toxic and non-degradable,mainly pollutes the water,soil and atmospheric environment,and enters the human body through the food chain,which can easily hinder the biological activity and normal metabolism of cells,thereby leading to physiological and biochemical dysfunction of the body,causing serious threat to people’s life and health.Rutin is a flavonol glycoside,which mainly exists in medicinal and food homologous foods such as Sophora japonica immaturus and Sophora japonica.It has antioxidant,anti-inflammatory,anti-cardiovascular and cerebrovascular diseases and other effects,and plays an important role in fields of dietary regulation,functional food development and clinical treatment.Rutin is often used as an important reference standard for quality evaluation of Sophora japonica immaturus,and its quantitative detection is particularly important to ensure the quality of functional foods.In this paper,fluorescence sensing systems of rhodamine 6G hydrazide（R6GH）probe and fluorescent molecularly imprinted photonic crystals hydrogel（FMIPH）were constructed using rhodamine dyes and carbon dots（CDs）as fluorescent substances,heavy metal Pb²⁺and active ingredient rutin in foods as analytes.The optimal environments for the constructed dual-mode sensing platform of fluorescence and visualization for Pb²⁺detection based on the ring-opening reaction between Pb²⁺and R6GH probe were acetonitrile and tetrahydrofuran:H₂O（1:1）solution.In the concentration range of 0.05-6.0μM,the R6GH probe showed good liner response to Pb²⁺,with a limit of detection of0.02μM.The spiked recoveries for real samples of tap water,soil,fish and shrimp were84.0%-102.0%;the developed visual paper-based array sensor realized the naked eye detection of Pb²⁺at 2.5μM,and a good linear response was obtained in the concentration range of 1.0-50.0μM through combining with LAB colorimetric analysis,which can realize accurate fluorescence detection and visual semi-quantitative screening of Pb²⁺.A fluorescence sensing system based on CDs-embedded FMIPH strip was constructed for the quantitative detection of rutin content.Under the optimal imprinting conditions:the addition dosage of CDs was 250μL,and the molar ratio of rutin to 4-vinylpyridine and ethylene glycol dimethacrylate was 1:4:4.The detection of rutin by the FMIPH strip can reach dynamic adsorption equilibrium within 20 min,which can achieve 5 repeatability determinations of adsorption-elution.The FMIPH strip had a good fluorescence response to rutin within the linear concentration range of 2.5-40μg m L^-1,with a limit of detection of2.3μg m L^-1and a limit of quantitation of 7.2μg m L^-1.The spiked recoveries in Sophora japonica immaturus and Sophora japonica samples were 81.7%-95.6%（RSD<3.1%）,which can realize rapid identification and selective quantitative detection of rutin in complex matrices.