呋喃稠环基NIR-II发光共轭聚合物的设计、合成及活体成像研究

The long wavelength photons in the near infrared II region (NIR-II, 1000-1700 nm) can reduce scattering and lower spontaneous fluorescence effect in biological tissue , so the deeper tissue penetration depth can be obtained, which makes the NIR-II luminescent materials promising in in vivo imaging field. However, as the core part of NIR-II bioimaging, the NIR-II luminescent materials, especially NIR-II conjugated polymer, are very limited. This project focuses on synthesizing a series of fused furan ring electron donor unit, through molecular structure's rational design, copolymerizing with different strong fluorescence electron acceptor unit to obtain furan fused polycyclic based NIR-II luminescent conjugated polymers. The effects of different structures such as molecular framework on the properties such as the emission wavelength and luminescence intensity will be systematically studied. New methods and fundamentals to the preparation of high brightness NIR-II polymers will be well explored. Moreover, photophysical and photochemical mechanisms will also be deeply investigated. Finally, we will perform cardiovascular and cerebrovascular disease diagnosis as typical examples, using preferred 8-12 highly efficient NIR-II luminescent polymers for in vivo bioimaging. The research will be of great significance for the development of new organic/polymer optoelectronic materials, enriching NIR-II luminescent material system and improving the theoretical research and practical application of NIR-II imaging.

近红外II区（NIR-II，1000-1700 nm）的长波长光子可以降低散射且有低的自发荧光效应，因此在生物体内有深的组织穿透深度，使得NIR-II发光材料在活体成像领域展示广阔的前景。然而作为NIR-II成像核心的NIR-II发光材料特别是NIR-II发光聚合物很有限。本项目拟将研究重点放在合成一系列呋喃稠环电子给体单元，通过理性的分子设计，调节与之共聚的不同类型荧光较强电子受体单元来获得NIR-II发光共轭聚合物。系统研究不同分子骨架等结构对发光波长和发光强度等性能的影响。对制备高亮度NIR-II聚合物的新方法和新途径进行探索，对发光机理进行深入研究，最后选定心血管和脑血管疾病诊断为实例，用优选的8-12个高效NIR-II发光聚合物，在活体小鼠上开展典型应用。该研究将对发展新型有机/聚合物光电材料，丰富NIR-II发光材料体系及完善NIR-II成像的理论研究和实际应用具有重要意义。

红外二区（NIR-II，1000-1700 nm）的长波长光子可以减少光散射作用和自发荧光效应，因此在生物体内有深的组织穿透深度，使得NIR-II发光材料在活体成像领域展示出广阔的前景。然而，作为NIR-II成像核心的NIR-II区发光材料特别是NIR-II发光聚合物很有限。本项目重点放在合成一系列NIR-II发光共轭聚合物，系统研究不同分子骨架等结构对发光波长和发光强度等性能的影响。对制备高亮度NIR-II聚合物的新方法和新途径进行探索，对发光机理进行深入研究，得到了如下成果：（1）制备了新型呋喃稠环类小分子发光化合物L1和L2，L2在非极性有机溶剂可以发出较强的蓝光，并得到了近100%的高荧光量子效率，研究了发光二极管的性能(Dyes and Pigments, 2019, 160, 353-360)；（2）制备了基于苯并三氮唑喹喔啉衍生物的聚合物纳米粒子，用于生物活体NIR-II荧光肿瘤靶向成像，实现在无创条件下，明显地看到肿瘤的大小和形状，该研究对肿瘤治疗和手术导航切除都具有重大意义(Macromolecules, 2019, 52(15): 5735-5740)；（3）首次研究了氟化作用对聚合物纳米粒在NIR-II区荧光信号强度的影响，并得到了强荧光信号的聚合物纳米粒子，聚合物纳米粒子水溶液在NIR-II区的荧光量子效率高达3.2%，同时，以该聚合物纳米粒子实现了生物活体NIR-II荧光脑肿瘤鼠脑血管成像定量分析。表明氟化作用在设计高亮度的NIR-II区荧光探针上具有巨大的潜力(Angewandte Chemie International Edition, 2020, 59: 21049-21057)。