隐形双靶纳米金的构建及其在肿瘤与相关新生血管协同靶向治疗中的应用研究

Targeting therapy of tumors in their early stages is crucial to increase the survival rate of cancer patients, targeting gold nanorods show the unique advantages and good prospect in the early photothermal therapy. However, the prepared targeting gold nanorods have the disadvantages of single targeting, unstable circulation and interaction with normal cells, which restrict the application of targeted therapy in vivo. According to our previous studies and literature reports, adopting acidic solid tumor microenvironment or multiple targeting mode can contribute to the accumulation of targeted nano-carrier in the tumor site. This project intends to bind covalently cRGDfK and folic acid to the surface of PEGlated gold nanorods, and conjugate a shielding molecule DTPA at the end of the cRGDfK by pH sensitive hydrazone to prepare stable stealth dual targeting gold nanorods. We will investigate the stability, designated targeting at acid solid tumor and synergistic targeted-photothermal therapy of tumor and Associated Angiogenesis using stealth dual targeting gold nanorods. Through associating the acidic solid tumor environment with the dual targeting mode, targeting precision and targeted amplification efficiency of gold nanorods are explored, which will provide research basis for targeting photothermal therapy in vivo.

肿瘤早期靶向治疗非常重要，能够提高癌患者的存活率，靶向纳米金在肿瘤早期光热治疗中显示出独特优势和良好应用前景。但目前构建的靶向纳米金具有靶向单一性、体内循环不稳定以及与正常细胞相互作用等缺点，在体内靶向光热治疗中受到限制。根据我们前期的研究以及文献报道，利用实体瘤的酸性微环境或采用多重靶向模式，可有助于纳米靶向载体的在肿瘤位点的积累。本项目拟在PEG纳米金表面共价偶联双配体cRGDfK与叶酸，且在cRGDfK末端通过pH敏感腙键连接DTPA，构建稳定的隐形双重靶向纳米金，并对其稳定性、酸性实体瘤定点靶向以及在肿瘤细胞与其相关新生血管内皮细胞协同靶向作用进行评价。通过上述肿瘤酸性微环境与双靶模式的结合，探讨纳米金在肿瘤部位的靶向精准度以及靶向放大效率，为纳米金体内靶向光热治疗提供基础。

纳米金棒的靶向光热-化疗协同治疗模式在肿瘤综合治疗中发挥重要作用，其不仅能够提高肿瘤患者的存活率，而且能够实现精准治疗及个体化治疗。本研究中，我们首先构建了聚乙二醇（PEG）修饰的金纳米棒，并通过异质性双功能的PEG赋予金纳米棒双靶特性，cRGDfK能够与肿瘤新生血管内皮细胞高丰度的整合素特异性结合，而叶酸能与多种肿瘤细胞过度表达的叶酸受体特异性结合，同时采用pH敏感腙键将化疗药物阿霉素装载到金纳米棒上，进而实现长循环、双靶、肿瘤酸性微环境响应的纳米金棒载药递送系统。体外、体内实验结果表明，该纳米系统不仅能够在酸性环境中可控释放阿霉素，而且能够靶向肿瘤新生血管与肿瘤细胞，实现其靶向协同光热治疗与化疗肿瘤目的；在此基础上，为了进一步提高化疗药物的装载能力及多模响应的药物控释功能，进而提高肿瘤高效治疗效率，我们通过碱性环境中多巴胺的自氧化及聚合作用在金纳米棒表面包覆一层聚多巴胺（PDA）有机聚合物层，其不仅能够高效、便捷的装载阿霉素，同时能够有效连接靶向功能化配体，实现近红外（NIR）与pH双响应的靶向光热-化疗高效抗肿瘤作用。体外实验结果证明，该纳米体系不仅能够特异性靶向CD13高表达的肿瘤细胞，而且阿霉素在NIR/pH双重响应下能够有效的可控释放，促进肿瘤细胞凋亡；荷瘤裸鼠体内研究表明，此纳米系统不仅能够在肿瘤部位有效蓄积，而且能高效抑制肿瘤生长、同时减少肿瘤复发几率。在本研究中，我们将实体瘤酸性环境、双模靶向及光热治疗与化学治疗联合治疗模式整合至同一纳米系统，实现高效光热-化疗协同治疗可肿瘤的目的，该研究可有效推动纳米材料在肿瘤临床诊疗一体化应用的研究发展。