基于DNA四面体纳米结构的脑靶向分子探针的设计、构建及应用

血脑屏障系统（Blood Brain Barrier）是脑部疾病的诊断和治疗性药物跨脑运输的瓶颈问题，几乎100%大分子和98%小分子药物都不能穿过BBB。纳米材料和技术能够帮助实现药物的脑部输送，但目前能够穿越血脑屏障的无机或有机高分子纳米材料面临着难降解、难排出体外等新的问题。本课题拟利用新型的无毒性、可降解的DNA纳米结构为平台，设计一个以Angiopep-2为脑靶向分子，以荧光和放射性核素为信号分子的多功能分子探针，实现脑部肿瘤的成像及药物递送，分别在细胞和动物水平上对其脑靶向行为进行研究，包括脑血管内皮细胞及脑胶质瘤细胞对多功能分子探针的摄取、细胞内定位及降解情况，原位脑胶质瘤荷瘤鼠的SPECT-CT成像及抗肿瘤药物的脑部靶向输送情况，最终构建一个能跨越BBB、实现脑部肿瘤细胞及原位瘤靶向的多功能分子探针，不仅为脑部肿瘤的诊断和治疗提供新的手段，也为DNA纳米材料的应用提供借鉴。

The blood−brain barrier (BBB) is a key challenge in the development of drugs for diseases of the central nervous system (CNS). Essentially，100% of large-molecule pharmaceutics and >98% of all small molecules can not cross the BBB. With the development of nanotechnology，the nanocarriers for delivering drugs make it possible to transport drugs across the BBB. Whereas，the cyto-toxicity and biodegradability of these nanomaterials brought about the new problem. In this study，we aimed to construct an multiple functional molecular probe for brain- targeted imaging and drug delivery based on DNA nanostucture. DNA tetrahedron was used as a platform and labeled with fluorenscence dye and radionuclide ，and modified with Angiopep-2（a 19 amino acid peptide of the LRP protein ligands . Finally，we design and construct a smart molecular probe with excellent brain targeting, stability ,biocompatibility. The cell uptake, location and degradation of this probes was studied in U87 and bEnd.3cell. And the SPECT-CT imaging and the brain glioma inhibition of this probe was investigated in the glioma-bearing mice. The research will provide a reference for the construction of brain targeted molecular probe based on DNA nanostructure , brain targeted drug delivery and Radioisotope labeling of DNA nanostructure .