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稀土掺杂上转换荧光纳米材料因其近红外区激发,可见光区发射的特殊发光性能,在生物标记方面具有独特优势,可大幅度降低荧光背景.β-NaYF4:Yb,Er是目前已知的发光效率最高的上转换荧光纳米材料之一,已在生命分析及生物成像分析领域展现出了广阔的应用前景.然而,由于现有β-NaYF4:Yb,Er制备工艺多是在高温条件下于高沸点有机溶剂中反应制得,所得产品在水溶液中的分散性差,限制了其在生命分析中的广泛应用.本文采用聚丙烯酸(PAA)配体交换反应,对表面包覆油酸基团的疏水β-NaYF4:Yb,Er纳米粒子进行了有效的表面修饰.表面修饰后,上转换荧光纳米粒子表面的PAA具有众多游离羧基,使其在水溶液中具有良好的分散性.同时,由于羧基的存在,使得带有氨基的生物分子能够通过化学交联反应结合到纳米粒子表面.本文以PAA表面修饰后的β-NaYF4:Yb,Er纳米粒子为荧光探针,以磁珠作为免疫反应的载体,成功构建了一种新型免疫传感器,对模型靶标分子羊抗人IgG进行了灵敏检测.磁珠表面固定兔抗羊IgG,PAA修饰的β-NaYF4:Yb,Er纳米粒子表面连接人IgG,当样品中存在羊抗人IgG时,便会在磁珠表面形成(兔抗羊IgG-羊抗人IgG-上转换荧光纳米粒子标记的人IgG)三明治式免疫复合体,通过磁分离除去未反应的组分,在980nm激光激发下测定免疫复合体的上转换荧光强度,即可实现靶标分子的高灵敏分析,可检测到低至0.1ng/mL的羊抗人IgG.同时,以磁珠为载体的免疫复合体也可通过激光扫描共聚焦荧光显微镜进行荧光成像分析,背景荧光信号低,成像质量高.实验结果表明,PAA修饰的β-NaYF4:Yb,Er上转换荧光纳米粒子是一种理想的生物标记材料,有望在生物传感及生物成像分析领域获得广泛应用.
Rare-earth doped upconverting luminescent nanomaterials have special luminescent properties due to their near-infrared excitation and visible light emission, which have unique advantages in biomarker and can greatly reduce the fluorescence background.β-NaYF4: Yb, Er are currently known One of the up-conversion fluorescent nanomaterials with the highest luminescence efficiency has shown broad application prospects in the field of life analysis and bioimaging analysis.However, due to the existing preparation process of β-NaYF4: Yb, Er mostly under high temperature conditions High boiling point organic solvent, and the poor dispersibility of the obtained product in aqueous solution limits its wide application in life analysis.In this paper, polyacrylic acid (PAA) ligand exchange reaction was used to investigate the effect of surface-coated oleic acid Hydrophobic β-NaYF4: Yb, Er nanoparticles.After the surface modification, the PAA on the surface of the up-conversion fluorescent nanoparticles has many free carboxyl groups, so that it has good dispersibility in aqueous solution.At the same time, Exist, so that the amino-containing biomolecules can be chemically cross-linked to the surface of the nanoparticles.In this paper, the PAA surface modified β-NaYF4: Yb, Er nanoparticles as a fluorescent probe, As a carrier of immune response, magnetic beads were successfully constructed as a novel immunosensor for the sensitive detection of the model target goat anti-human IgG.The rabbit anti-goat IgG and PAA modified β-NaYF4: Yb and Er nano Human IgG is attached to the surface of the particle. When the sample contains goat anti-human IgG, a sandwich immunocomplex is formed on the surface of the magnetic beads (rabbit anti-goat IgG-goat anti-human IgG-up-converting fluorescent nanoparticle labeled human IgG) Removal of unreacted components by magnetic separation and upconversion fluorescence intensity of the immune complexes under 980 nm laser excitation provides highly sensitive analysis of the target molecules and detection of goat anti-human IgG down to 0.1 ng / mL. At the same time, the immune composite with magnetic beads as the carrier can also be analyzed by laser scanning confocal fluorescence microscope for fluorescence imaging with low background fluorescence signal and high imaging quality.The experimental results show that PAA-modified β-NaYF4: Yb, Er upconversion Fluorescent nanoparticles are an ideal biomarker material and are expected to find wide applications in the fields of biosensing and bioimaging.