水溶性稀土上转换发光纳米材料的尺寸和形貌控制及在免疫层析中的应用

The upconversion immunochromatography in which upconversion luminescence materials are used as biomarkers is the way to realize a new detection technique with the high sensitivity. A paradox between the upconversion luminescence materials and the result of immunochromatography is that the smaller the particle size is, the lower the upconversion luminescence efficiency is, but the higher the sensitivity is. This paradox limits to improve the sensitivity of the upconversion immunochromatography. In our study, we should synthesize high efficient upconversion luminescence nano materials and study their luminescent properties. The goal of our project is to use our synthesized materials to substitute the submicron materials used in present upconversion immunochromatography. Firstly, the water dispersible core/shell LaF3/SiO2 upconversion luminescence materials are synthesized by sol-gel method. The particle size should be smaller than 100nm by controlling the synthesis conditions. Then rare earth ions doped NaYF4 are synthesized by thermal decomposition method with the particle size smaller than 50nm, The element La or Gd will be introduced in the host material NaYF4 to improve the phase transformation. The red, green and blue color upconversion luminescence materials should be synthesized respectively by doped different rare earth ions. The upconversion mechanism, especially the upconversion intensity along with the changing of the particle size, will be investigated deeply. The questions should be answered that whether the phonon confinement effect or the surface effect is the main effect for the changes of the upconversion luminescence along with the decreasing of the particle sizes. The synthesis conditions of upnconversion nanoparticles should be optimized according to the results of upconversion immunochromatography.

纳米上转换发光材料与免疫层析技术的融合，是实现高敏感检测的重要途径。而现有上转换荧光免疫层析中颗粒尺寸、发光效率及层析效果三者之间的悖论，却限制了敏感性的进一步提升。本课题目标是合成高发光效率、水溶性的纳米上转换发光材料，控制材料的尺寸和形貌，用所制备的上转换发光颗粒取代现有上转换荧光免疫层析中通常使用的亚微米级上转换荧光颗粒。首次用S-G方法一步合成稀土离子掺杂的LaF3/SiO2核壳结构的纳米上转换发光材料，摸索合成条件，控制其颗粒尺寸小于100nm；用热分解方法制备NaYF4纳米材料，通过在基质中引入La或Gd离子，改善NaYF4基质材料的形貌，得到尺寸小于50nm的上转换发光材料，通过不同稀土离子的掺杂，实现高效的红、绿、蓝上转换发光；深入研究上转换发光强度随材料粒径及其它因素变化的机制，将不同粒径、不同形貌的上转换发光颗粒制备成层析试纸，并通过层析效果进一步指导材料的制备。

纳米上转换发光材料与免疫层析技术的融合，是实现高敏感检测的重要途径。而现有上转换荧光免疫层析中颗粒尺寸、发光效率及层析效果三者之间的悖论，却限制了敏感度的进一步提升。. 在这项工作中，合成了单分散、平均粒径为25nm的NaYF4:Yb3+,Er3+上转换发光纳米颗粒。并在此的基础上，通过调节反应条件和掺杂质离子（Ce3+, Gd3+,Yb3+，Mo3+，Mg2+, Li+, K+）使上转换纳米材料的上转换发光强度得到了大幅度增强，并可以进行发光颜色的调控、晶相、形貌、粒径的调控。所制备的上转换发光颗粒可以用来取代现有上转换荧光免疫层析中通常使用的亚微米级上转换荧光颗粒。深入研究上转换发光强度随材料粒径及其它因素变化的机制，将不同粒径、不同形貌的上转换发光颗粒制备成层析试纸，并通过层析效果进一步指导材料的制备。. 同时，采用SiO2包覆、ZnO包覆及BaF2包覆手段对合成的纳米颗粒进行了表面改性，改善后的纳米颗粒仍然具有良好的单分散性，并且在兼顾尺寸、上转换发光强度的条件下，实现了UCNPs的表面亲水性和生物兼容性。为了改善上转换纳米粒子的实验条件和性能，通过大量实验包括不同的离子掺杂以及核壳结构的表面改性，使上转换纳米颗粒在具有高灵敏度的免疫层析技术应用中拥有更大潜力。