Construction Of Three Fret Sensors Based On Up-conversion Fluorescence Materials

Rare earth up-conversion fluorescent nanomaterial is a new type of fluorescent material that converts long-wavelength near-infrared excitation light into short-wavelength visible light.Due to its unique properties,it has attracted widespread attention of researchers in laser devices,solar cells,photothermal therapy,biochemical sensing,and other fields.Rare earth upconversion fluorescent nanomaterials have advantages in fluorescence imaging,fluorescent chemical biosensors,and photodynamic therapy due to their deeper tissue penetration,high chemical stability,low toxicity,and excellent signal-to-noise ratio.Based on the phenomenon of fluorescence resonance energy transfer,the concentration analysis of coumarin,melamine,and glucose was realized by constructing a fluorescence sensor.The main innovations and research contents of this paper are as follows:(1)Hexagonal and tetragonal NaYF₄:Yb;Er nanoparticles were prepared by the hydrothermal method.With the prepared NaYF₄:Yb;Er nanoparticles,a coumarin fluorescence sensor based on a fluorescence resonance energy transfer system was constructed.In this system,host-guest recognition is used as molecular recognition method,NaYF₄:Yb;Er modified with cyclodextrin are used as energy donors,and rhodamine 6G is used as a fluorescent acceptor.The competitive combination of cyclodextrin enables the detection of coumarin concentration.(2)As a substance harmful to the human body,it is of great significance to develop a simple method to detect melamine concentration.Core-shell type up-conversion nanoparticles NaYF₄:Yb;Er@NaYF₄ were solvothermal used.The Ligand-free nanoparticles are used as fluorescent donors,and the melamine-bound AuNPs are used as a fluorescent acceptor,which facilitates the process of fluorescence energy transfer between the two and constructs a melamine fluorescent chemical sensor.After mixing melamine and AuNPs,the intensity of the absorption peak of AuNPs decreases,and the efficiency of fluorescence resonance energy transfer decreases with the addition of up-converted nanoparticles,thereby constructing a melamine fluorescent chemical sensing system.(3)Based on the fluorescence resonance energy transfer system,808 nm excited groundconverted fluorescent nanomaterials NaYF₄:Yb;Er;Nd@NaYF₄ were selected as fluorescent substances.An up-converted nanoparticle modified with glucose oxygenase was used as an energy donor,and dextran-modified AuNPs particles were used as energy acceptors.A fluorescent biosensor with good selectivity,simplicity,and convenience was constructed.The specific detection of glucose content was realized by the change of fluorescence intensity of the system.