壳聚糖基聚集诱导发光荧光探针的分子设计及其生物成像性能的研究

Fluorescent probes used to detect important biological events in living cells or animals are increasingly demanded in the biological and biomedical fields. Aggregation-induced emission (AIE) fluorescent probes with single functional group (-CHO, -NCS), and with yellowgreen or near infrared emission properties will be designed and synthesized. The relationship between molecular structure and fluorescent properties will be clarified in this research. To improve the hydrophilic properties of AIE dyes and their miscibility with physiological buffer, chitosan will be chosen as molecular platform for chemical modification due to large amount of hydroxyl and amino groups on its macromolecular chain. Aldehyde or isothiocyanate groups could be easily reacted with amino groups, so AIE with single functional group (-CHO, -NCS) could be labeled onto chitosan macromolecular chains efficiently. Meanwhile, PEG will be grafted onto chitosan macromolecular chains by "click" chemistry to achieve the long-term circulation in the blood; folic acid will be labeled onto chitosan macromolecular chains for tumor targeting. Functional chitosan-based AIE fluorescent probes will be used for the cell tracing and tumor targeting experiments. It is very important to explore how to control the long-term circulation in the blood, and the cell tracing and tumor targeting properties by adjusting the molecular weight of PEG, and grafting ratio of PEG, folic acid and AIE. This novel chitosan-based AIE fluorescent probe has great promising applications for long-term cell tracing, tumor diagnosis and drug metabolism in the future.

荧光探针用于生物学检测引起了广泛关注。本项目以含有大量羟基和氨基的天然高分子壳聚糖为分子载体，旨在设计一种可在血液中长循环、具有肿瘤主动靶向功能、适于动物组织成像的聚集诱导发光（AIE）荧光探针：合成含单功能团（-CHO, -NCS），并能发射黄绿色荧光或近红外光的AIE荧光分子，掌握AIE荧光探针发射波长的调控方法，探明AIE荧光探针的分子结构与荧光性能之间的关系；采用"click"反应将PEG接枝到壳聚糖链上，并将叶酸和AIE分子标记到壳聚糖链上，最终进行细胞示踪实验和动物肿瘤成像评价，探明PEG的分子量和接枝率，以及叶酸和AIE分子的接枝率对荧光探针在血液中的循环时间和对肿瘤细胞示踪性能、动物肿瘤部位靶向功能以及肿瘤部位成像分辨率的影响。从分子水平上调控壳聚糖基AIE荧光探针的性能，为该新型荧光探针在细胞示踪、肿瘤诊断和药物代谢等方面的应用奠定基础，具有重要的科学意义和应用前景。

荧光探针已广泛应用于生物监测和材料结构分析。本项目设计、合成了一种含有异硫氰酸酯官能团（-NCS）的聚集诱导发光（AIE）荧光分子，并成功标记到壳聚糖大分子链上，研究了壳聚糖基AIE荧光探针的分子结构、标记率与荧光性能之间的关系，发现简单地通过调控荧光分子的标记率就可以极大地提高产物的荧光强度。采用“click”反应将PEG接枝到壳聚糖链上，然后标记AIE荧光分子，制得的产物具有良好的水溶性和长周期示踪癌细胞的性能；采用琥珀酰化的方法制备了水溶性壳聚糖基AIE荧光探针，可以示踪癌细胞至30代，实现了癌细胞超长周期示踪的目的。此外，还采用AIE探针示踪了壳聚糖与海藻酸钠的层层组装过程和壳聚糖碱性溶剂体系的凝胶化过程，为实时、原位检测材料形成过程与结构提供了一种新思路、新方法。壳聚糖基AIE荧光探针在癌细胞示踪检测和材料结构形成过程的示踪检测方面具有重要的科学意义和应用价值。