水散性硅酸盐纳米晶制备及其射线辐照发光机制研究

As radioluminescence materials, rare-earth activated nanocrystals have exhibited potential application in photodynamic therapy (PDT) for cancer treatment under X-ray irradiation. But the transfer efficiency from X-ray to fluorescence needs to be improved, which relates to the interaction between nanocrystals and X-ray with short wavelength and high energy. The transfer efficiency is also related to the crystal structure of hosts, sizes and surface effects of nanocrystals, and the defects in the nanocrystals. In order to improve the radioluminescence efficiency of rare-earth activated nanocrystals under X-ray irradiation, in this project, rare-earth activated silicates nanocrystals containing lutetium will be controllable synthesized. The oriented growth mechanism of the obtained rare-earth activated silicates nanocrystals and the transportation process of ions in the solution will be investigated. For avoiding the precipitation of silicate nanocrystals from the water solution, the surface properties of silicate nanocrystals and the interaction between the surface and modified molecules will be studied and the surface will be modified to make the nanocrystals well dispersible in water. Considering the fact that the sizes of nanocrystals is shorter than the wavelength of ultraviolet light and much longer than the wavelength of X-ray, the luminescence dynamic processes of the silicate nanocrystals under X-ray and ultraviolet light excitation will also be studied in order to reveal the radioluminescence mechanism of nanocrystals doped with rare-earth ions.

稀土掺杂纳米晶作为射线辐照荧光转换材料在肿瘤光动力治疗中已展现出潜在应用前景，但其荧光转换效率有待提高。纳米晶对高能射线的荧光转换效率和高能射线与纳米晶的相互作用有关，涉及到材料基质晶体结构、纳米晶的尺寸效应、表面效应、以及缺陷等方面。为提高稀土掺杂纳米晶对高能射线能量的荧光转换效率，促进其在生物医学中的应用，本项目拟用高密度含镥硅酸盐为基质，掺入具有允许跃迁的稀土铈离子，通过可控合成，获得不同尺寸稀土掺杂硅酸盐纳米晶，研究纳米晶生长过程中的离子输运机制和晶面取向生长机制；通过表面性质研究与对纳米晶进行表面修饰，研究纳米晶表面与修饰分子之间的相互作用，掌握规律，使其可稳定地分散在水溶液中；用X-射线和紫外光分别激发含镥硅酸盐纳米晶，通过对比分析其荧光量子效率和发光动力学行为，研究稀土纳米晶在X-射线激发下的发光性质，揭示稀土掺杂纳米晶与高能射线的相互作用机制。

本项目分别用溶胶凝胶法与共沉淀法合成了三价稀土铈离子（Ce3+）掺杂的硅酸镥（氧正硅酸镥Lu2SiO5:Ce3+和焦硅酸盐Lu2Si2O7:Ce3+）纳米晶，通过改变纳米晶生长条件，揭示了稀土硅酸盐纳米晶的可控生长机制，并用环境友好且具有生物相容性的二氧化硅进行修饰，组装成了具有核壳结构的稀土硅酸盐/二氧化硅复合纳米晶，研究了稀土硅酸盐/二氧化硅复合纳米晶的组装机制及其射线辐照发光性能，既实现了纳米晶在高能射线辐照下的高效蓝紫荧光发射与卟啉类光敏剂的Soret强吸收带（380-480 nm）高度匹配，又改善了纳米晶的生物相容性，在X-射线辐照光动力治疗肿瘤方面有潜在应用。基于所制备得到的稀土硅酸盐/二氧化硅复合纳米粒子对紫外光有较好的吸收性能，项目组用丰度稀土元素钇替代稀缺稀土元素镥，开展了稀土硅酸钇/二氧化硅复合纳米材料的抗紫外性能研究，通过稀土离子共掺，实现了稀土硅酸钇/二氧化硅复合纳米材料对紫外光的全吸收，同时降低了材料的原料成本。项目组将所研发的成果申请了发明专利并获得了授权，且向企业授权转让专利技术，将所研发的稀土硅酸盐/二氧化硅复合纳米材料推广应用到抗紫外防晒霜和汽车玻璃涂层领域，克服了现有产品二氧化钛在紫外光辐照产生二次电子伤害皮肤和环境不友好的缺点，同时促进了丰度稀土元素钇和铈的高价值利用。