基于AIE效应的高效近红外二区聚合物量子点（Pdots）的设计、合成及生物成像应用

活体荧光成像技术发展的主要瓶颈是：低组织穿透深度和低空间分辨率。近红外二区荧光探针的应用是解决上述问题的有效途径。本项目结合聚合物量子点（Pdots）和AIE聚合物材料两个方向上已有研究基础，拟采用开环和可逆加成-断裂链转移（RAFT）活性聚合技术，分别将疏水性聚己内酯和具有代表性的亲水性聚合物（如：聚丙烯酸，聚乙二醇，聚丙烯酰胺）共价偶联于近红外二区AIE分子上，以形成两亲性聚合物，再通过自组装技术合成Pdots，从而制备出新颖的、具有生物相容性、高亮度和纳米粒径可控的AIE近红外二区荧光探针。通过生物荧光成像应用研究，揭示聚合物链结构和纳米粒径对Pdots荧光成像的影响关系及变化规律，阐明成像材料的最佳结构与粒径范围。本研究不仅为生物成像技术提供近红外二区纳米荧光探针，对纳米粒径如何影响生物成像的关键科学问题也具有理论指导意义，且为高性能近红外Pdots材料的生物应用奠定基础。

The low tissue penetration and spatial resolution are the main bottlenecks of developing in vivo fluorescence optical imaging technology. Application of the near-infrared II fluorescence probe is the efficient way to solve the above-mentioned problem. Based on our research foundations in the fields of polymer dots and aggregation-induced emission (AIE) polymer, a new AIE near-infrared II nonconjugated Pdots with good biocompatibility, high brightness and controllable nanoparticle size will be synthesized based on the reversible addition-fragmentation chain transfer polymerization (RAFT) in this project. Firstly, an amphiphilic polymer could be prepared by the covalent coupling of hydrophobic polycaprolactone and representative hydrophilic polymers, such as polyacrylic acid, polyethylene glycol and polyacrylamide, to near-infrared II AIE luminogen. Then, Pdots will be formed by a self-assembling process. The correlations between chain structure, particle size and imaging effect of Pdots will be studied systematically, and the most favourable chain structure and particle size for biological imaging will be verified. The study can not only offer a new near-infrared II fluorescent nanoprobe for bioluminescence imaging, and it has guiding significance to reveal the correlation between particle size and imaging effect of fluorescent nanomaterials, but also can build stable foundation for the application of high-performance near-infrared Pdots nanocomposites in the field of bioimaging.