Investigation Of The Development And Application Of Rare Earth Upconversion Fluorescence Nanosensors

Fluorescence sensors have been widely used in various biological detections due to their relatively simple,fast,low-cost,and sensitive characteristics.In this dissertationan,upconversion fluorescent nanosensors are prepared by the co-precipitation method for the detection of anthracycline anticancer drugs.The main research contents are as follows:(1)Synthesis and surface modification of upconversion nanomaterials.The prepared Nd³⁺-doped upconversion fluorescent nanosensor(Nd³⁺-UCNPs)can change the excitation wavelength to 808 nm.The hydrothermal effect is reduced,and 808nm wavelength light has strong tissue penetration,which can be better used in biological detection.The NaYF₄:Yb/Er/Nd nanocrystalline core of the fluorescence sensor is synthesized by the co-precipitation method.In order to enhance the fluorescence intensity,the NaYF₄:Nd nanocrystalline shell is grown on the core through the epitaxial growth method.To improving the water solubility,the oleic acid ligand on the surface of the core-shell UCNPs is removed by acid treatment to obtain an upconversion fluorescent sensor that can be used to detect epirubicin.In order to further improve the specificity,the ligand-free core-shell UCNPs are modified,and an aptamer-modified upconversion material(Apt-Nd³⁺-UCNPs)fluorescent sensor is synthesized.The characterization results obtained by transmission electron microscopy,fluorescence spectroscopy,X-ray diffraction,Fourier transform infrared spectroscopy,ultraviolet spectroscopy,etc.prove the success of the preparation and modification of the upconversion fluorescent nanoparticles.(2)Application of the Nd³⁺-UCNPs sensor in the detection of epirubicin.The results of fluorescence spectrum and ultraviolet spectrum show that the emission spectrum of Nd³⁺-UCNPs coincides with the absorption spectrum of epirubicin.Epirubicin can be quantitatively detected based on the mechanism of fluorescence resonance energy transfer.Under the optimal condition,the quenching efficiency of the fluorescence sensor is linearly related to the concentration of epirubicinin in the range of 0.09?M to 189.66?M with a detection limit of 0.05?M,and the linear correlation coefficient is 0.994.In the experiment of recovering epirubicin in urine samples,the recovery rate of epirubicin in urine is in the range of 97.5 to 102.6%,indicating that the Nd³⁺-UCNPs sensor can be used to detect epirubicin in human urine.(3)Apt-Nd³⁺-UCNPs sensor in paper-based microfluidic chip for detection of adriamycin.The paper-based microfluidic chip greatly reduces the usage of upconversion nanomaterials.Based on the paper-based chip,a fluorescence spectrophotometry detection system and a mobile phone photography detection system are established.The quenching efficiency of the fluorescence sensor is linearly related to the concentration of adriamycin in the ranges of 0.01?M to 150?M.For the mobile phone photography detection,the fluorescence intensity of upconversion fluorescent nanosensor in paper chip is calculated using Image J fluorescence analysis software.Under the optimal detection conditions,the fluorescence intensity decreases linearly with the increase of adriamycin concentration and the detection range is 1?M to 70?M.