LRP1-targeted carbon nanodots for crossing BBB and delivering small molecule or protein drugs into brain

血脑屏障（BBB）严重阻碍了包括胶质瘤和帕金森病（PD）在内的严重脑疾病的治疗。克服血脑屏障并将药物靶向病变区域长期以来一直是有效治疗脑疾病的挑战性课题。基于纳米颗粒的受体介导的靶向递送已被认为是克服BBB的重要策略。在本项目中，掺杂碳点（CD）将被开发为基本药物载体，因为先前证明CD在靶向BBB穿越中具有积极的特性，作为成像探针，其方便的5-20 nm的小尺寸，高稳定性和载药量，以及适用于光热治疗。将努力探索最佳CD的简便合成方法。将进行表面改性以用于跨越BBB的主动转胞吞作用。低密度脂蛋白受体相关蛋白1（LRP 1）是一种跨膜受体，不仅在血脑屏障中高度表达，而且在帕金森病的胶质瘤细胞和黑质（SN）的黑化神经元中也高度表达。本项目在噬菌体展示筛选技术获得的LRP 1配体肽L57的基础上，通过一系列技术进一步优化LRP 1结合肽配体，包括设计代谢稳定的逆对映体（D）肽，环化，甲基化或末端修饰的类似物，这些都将通过固相化学合成，包括适当的接头分子。CD将与通过亲水性聚乙二醇（PEG）接头连接的LRP 1配体肽（LP）缀合，并装载有模型抗肿瘤药物阿霉素（DOX）或左旋多巴（LD）作为PD的模型药物。此外，胶质细胞源性神经营养因子（GDNF）将作为PD的模型蛋白药物，通过CD的新型脂胶束涂层进行测试。将在体外和体内系统地评价CD-PEG-LP药物递送系统。两种已建立的脑疾病动物模型，胶质瘤和PD，将用于评估药物向脑的递送机制以及药效学效果。相关结果将极大地促进跨胞吞血脑屏障纳米系统的发展，并为严重脑疾病提供额外的治疗策略。

The blood-brain barrier (BBB) significantly hinders the treatment of severe brain disorders including glioma and Parkinson’s disease (PD). Overcoming the BBB and targeting drugs to diseased areas has for long been a challenging topic for efficient therapy of brain diseases. Nanoparticle-based receptor-mediated targeting delivery has been considered as an important strategy for overcoming the BBB. In the current project, doped carbon dots (CDs) will be developed as the basic drug carrier, because of previously demonstrated positive characteristics of CDs in targeted BBB crossing, as an imaging probe, their convenient small size of 5-20 nm, high stability and drug loading capacity, and suitability for photothermal therapy. Efforts will be made to explore facile synthesis methods of optimal CDs. Surface modification for active transcytosis across BBB will be pursued. Low-density lipoprotein receptor-related protein 1 (LRP1) is a transmembrane receptor that is highly expressed not only in the BBB but also in glioma cells and in melanised neurons of the substantia nigra (SN) in PD. In this project, based on a recently described LRP1 ligand peptide L57 obtained by phage display screening technology, LRP1-binding peptide ligands will be further optimized by a series of technologies, including design of metabolically stabilized retro-enantio (D) peptides, cyclized, methylated, or end-modified analogs, which all will be synthesized via solid phase chemistry including appropriate linker molecules. CDs will be conjugated with LRP1 ligand peptides (LP) attached via hydrophilic polyethylene glycol (PEG) linkers and loaded with either the model anti-tumor drug doxorubicin (DOX), or levodopa (LD) as model drug for PD. Additionally, glial cell line-derived neurotrophic factor (GDNF) will be tested as model protein drug for PD by novel lipo-micellar coating of the CDs. The CD-PEG-LP drug delivery systems will be evaluated systematically in vitro and in vivo. Two established brain disorder animal models, glioma and PD, will be used to evaluate the drug delivery mechanisms to the brain and also the pharmacodynamic effect. Relating results will greatly promote the development of transcytotic BBB crossing nanosystems and provide additional therapeutic strategies for severe brain disorders.