基于核壳结构调制提高稀土上转换纳米材料/染料能量传递效率的机理研究

The bare core structure of rare earth upconversion nanomaterials is dominantly adopted in their energy transfer based applications due to the knowledge of nonradiative Förster resonant energy transfer (FRET) mechanism. However, in our previous work, it was demonstrated preliminarily but powerfully that the construction of core/shell structure of the upconversion nanomaterials could enhance greatly the energy transfer efficacy. In order to obtain a thorough understanding of the energy transfer mechanism between core/shell structured upconversion nanomaterial and the bound acceptor, thus providing guidance for the design the relevant system, core/shell structured upconversion nanoparticle-dye energy transfer system with the dye serving as energy acceptor will be studied systematically in this proposal. Taking into account both FRET and reabsorption, the effects of the arrangement, distribution and mutual interaction of the dyes, the upconversion efficiency of the upconversion nanoparticles and the donor-acceptor distance on the energy transfer efficacy will be investigated. The quantitative relation between the optimal shell thickness and the size of the core will be provided. Furthermore, the physical model of the involved energy transfer mechanism will be built based on the combination of the above experimental results and the theoretical results obtained with integral operation of the energy transferred via FRET and reabsorption from various rare earth emitters to the dyes. Based on the above results, core/shell structured upconversion nanoparticles will be utilized in photodynamic therapy.

基于无辐射Förster共振能量传递（FRET）机制，稀土上转换纳米材料在基于能量传递的应用中通常采用裸核结构，而我们的前期工作初步但有力地证明了核壳上转换纳米结构的构筑可大大提高能量传递效果。为了更加全面、深入、系统地理解核壳结构上转换纳米材料与其表面受体之间的能量传递机制，为相关体系的设计提供理论指导，本项目拟针对上转换核壳纳米粒子-受体染料分子体系，协同考虑FRET和再吸收作用，系统研究受体染料分子的排列分布、染料之间相互作用以及供体上转换纳米粒子的上转换效率及供受体距离变化对能量传递效果的影响，给出上转换纳米粒子的最佳壳层厚度与核尺寸的关系，并结合对大量稀土离子发光中心和染料分子对之间通过FRET和再吸收传递的能量进行积分得到的理论结果，建立两者之间能量传递机制的物理模型。在此基础上，对核壳结构上转换纳米粒子在光动力学治疗中的应用进行原理性展示。

基于无辐射Förster共振能量传递（FRET）机制，稀土上转换纳米材料在基于能量传递的应用中通常采用裸核结构，而我们的前期工作初步但有力地证明了核壳上转换纳米结构的构筑可大大提高能量传递效果。为了更加全面、深入、系统地理解基于核壳结构上转换纳米材料的能量传递机制，为相关体系的设计提供理论指导，本项目针对上转换纳米粒子-染料分子能量传递体系，协同考虑FRET和再吸收作用，系统研究了染料分子的偶联量、上转换纳米粒子的稀土掺杂浓度及壳层厚度等对能量传递效果的影响机制。在此基础上，我们对上转换纳米粒子-光敏剂能量传递体系在光动力学治疗中的应用进行了原理性展示，并构建了快速高灵敏生物检测平台。此外，我们利用上转换发光-磁性多功能纳米复合材料实现了磁靶向上转换发光细胞成像及上转换成像介导的高效肿瘤光热治疗。本项目为新型高效上转换纳米生物平台的构建提供了重要的理论和实验依据。