基于二氧化锰纳米层构建的多功能肿瘤靶向诊断治疗系统研究

It is of great importance to explore the new methods for cancer diagnosis and therapy simultaneously. This project aims to establish a multifunctional tumor-targeting drug delivery system for tumor diagnosis and therapy based on manganese dioxide nanosheets. The tumor-targeting peptide NGR against CD14 was conjugated with the tumor microenvironment sensitive manganese dioxide nanosheets through the polymer materials with outstanding biocompatibility. Due to the low pH and high concentration of reduced glutathione in the tumor microenvironment, manganese dioxide nanosheets will be degraded to Mn2+, which enables magnetic resonance imaging (MRI). Both chemotheraputic agent cis-platinum and the CRISPR/Cas9 system based human EGFR sgRNA (small guide RNA) are loaded into the system for tumor MRI as well as combination of chemotherapy and gene therapy. The CRISPS/Cas9 system is a newly developed gene silencing technology mediated by sgRNA targeting the target gene, which has the advantages of high efficiency and long effect. In this study, we will firstly investigate the CD14 receptor-mediated endocytosis of this system，the tumor inhibitory effect, the MRI property under the condition that mimics the in vivo tumor microenvironment in vitro. In addition, the pharmacokinetics and biodistribution, drug release profile and anti-tumor activity as well as MRI in vivo will also be studied for evaluating the tumor-targeting potential, MRI property and combinational treatment effect.

探索肿瘤诊断治疗一体化的新方法对于肿瘤的治疗具有重要意义。本课题拟研究一种基于二氧化锰纳米层的多功能肿瘤靶向诊断治疗系统。首先将具有肿瘤微环境响应特性的二氧化锰纳米层与靶向肿瘤血管CD14受体的NGR短肽(N：天冬酰氨酸, G：氨基乙酸, R：精氨酸)通过生物相容性高分子材料相连，然后装载化疗药物顺铂(CDDP)和新型基因药物CRISPR/Cas9技术介导的hEGFR sgRNA (small guide RNA)，制备诊断治疗一体化肿瘤靶向给药系统，实现肿瘤微环境响应下的MRI成像和联合治疗。CRISPR/Cas9技术介导的目标基因的sgRNA是一种新的基因沉默技术，具有效率高，作用时间长的优点。该系统借助 NGR 的肿瘤靶向性高效转递至肿瘤部位，实现基于二氧化锰纳米层降解为Mn+2的MRI成像，协同发挥CDDP细胞毒作用和CRISPR/Cas9依赖的EGFR sgRNA基因治疗作用。

我们已经成功建立了基于二氧化锰纳米层的多功能肿瘤靶向治疗成像系统，并且成功用于药物负载以及作为纳米粒的表面功能包覆层。我们首先制备了二氧化锰纳米层，并进行了表征。研究结果显示，该二氧化锰纳米层不但能够高效地负载化疗药物，而且具有响应肿瘤低pH/高GSH微环境降解的特性，从而释放治疗药物以及增强MRI功能的锰离子。体内外研究表明，该纳米层在体内外具有良好的T1-加权成像效果。研究显示，所构建的二氧化锰纳米层负载化疗药物顺铂和阿霉素的能力都较强，两者分别用透明质酸和叶酸-聚乙二醇聚合物修饰后，均成功实现了肿瘤的靶向治疗诊断功能。此外我们制备了表面负载二氧化锰层的纳米粒，利用二氧化锰的控释、降低GSH功能，成功用于增强光动力治疗和化疗。鉴于锰纳米粒作为MRI造影剂的巨大潜力，我们创新性地构建了一种磷酸锰纳米粒，也成功实现了肿瘤靶向诊断治疗功能。与此同时，我们还探索了其它肿瘤联合治疗策略的研究。通过本项目的实施，到目前为止已有9篇SCI论文发表，授权发明专利1项。通过本项目的实施，培养了六名硕士研究生和一名博士研究生。