Mechanism Of Upconversion Micro-nano Fluorescence Sensor And Its Application Research

Nowadays,with the continuous progress of information technology and the continuous improvement of people's quality of life,people's requirements for dietary health and living environment are also increasing,so the detection of food safety and contaminated gases is more urgent.Sensors,as devices or systems for information acquisition,have become a major industry of modern science and technology.Sensitive materials,as the core foundation of sensors,are an important part of the development of modern society and the promotion of various sensors.Rare earth doped oxide micro-nanocrystalline upconversion luminescent materials have broad application prospects in upconversion lasers,gas sensors,temperature sensors,immunoassay,bioimaging,DNA/protein detection and cancer detection in medical treatment due to their excellent optical,magnetic and electrical properties.In this paper,up-conversion nanoparticles were prepared by solvothermal method.A high-precision biosensor was constructed based on the up-conversion nanoparticles of biosensor.The rhodamine B organic dye residues in living plants were quantitatively detected by the biosensor.In this paper,upconversion micron particles are mainly prepared by hydrothermal method,based on gas sensors for quantitative detection of acetic acid molecules and other gases.The main work of this paper is as follows:?1?Upconversion nanoparticles Na Gd F₄:48% Yb³⁺,2% Er³⁺,Gd₂O₃ as matrix and Er³⁺ as activator were prepared by solvothermal method.Up-conversion nanoparticles are sensitive components for the fabrication of biosensors.Eventually,nanoparticles with uniform size and high luminescence intensity are synthesized.Upconversion nanoparticles emit brilliant visible light under the excitation of near infrared light at 980 nm.?2?The up-conversion nanoparticles of biosensor were used to trace the organic dye Rhodamine B in plants.Combining with the basic principle of fluorescence resonance energy transfer,the up-conversion nanoparticles are used to construct the sensing system.Because of the special relationship between up-conversion fluorescence spectrum and Rhodamine B concentration,the function model of up-conversion nanofluorescence ratio and Rhodamine B concentration is constructed.After calculating the ratio of yellow-green integral intensity,the corresponding Rh B concentration can be found,thus the tracing detection of Rh B in plants can be realized.?3?Up-conversion micron particles Na Lu F₄:18% Yb³⁺,2% Er³⁺ were prepared by hydrothermal method,using Lu₂O₃ as matrix and Er³⁺ as activator.By changing the content of sodium fluoride and trisodium citrate,the morphology and size of the prepared samples are different.Up-conversion micron particles with uniform size,uniform morphology and high luminescence intensity were synthesized by hydrothermal method.?4?A group of samples with the same morphology and size and beautiful appearance were selected to be corroded by succinic acid.The dried sample powders were corroded in succinic acid aqueous solution with PH=4,PH=3 and PH=2,respectively.It is found that with the increase of acidity of PH,the more serious the corrosion is,the clearer the stripes are.Finally,the molecule of acetic acid was detected in the corroded samples.The change of acetic acid molecule strength reveals two stages of acetic acid volatilization:the first stage which is close to linearity can be regarded as detection stage,in which upconversion luminescence intensity is a linear function of gas concentration.Because of the existence of saturated vapor pressure,the stable stage is saturated.If Upconversion Microcrystals is properly treated,the sensor can also detect NH₃,SO₂ and CO₂ according to the relationship between redox reaction or PH value and upconversion strength.