基于荧光金纳米簇的多功能载药纳米复合物构筑及其在肿瘤影像及靶向治疗中的应用研究

Multi-functional nanocomposites are novel drug carrier systems at the cross-point of mordern nanotechonology, pharamcy, molecular imaging and biology. This kind of nanocomposite is characterized with the outstanding features of targeting, in vivo imaging, easy surface modification, biocompatibility, anti-cancer activity and so on. Noble metal nanoclusters is a new type of luminescent nanomaterial composed of a few to tens of atoms. This feature has attracted a great deal of attention for their unique role in bridging the link between atomic and nanoparticulate behavior. Hear we aim to develop a platform thechnology that can solve the challenges in the design of multi-functional nano-composites for tumor-targeting imaging and therapy. Specifically, anti-cancer drug loaded nanocomposites (DOX@Au-APT-MPA) based on red fluorescence gold nanoclusters are contrusted, which will be provided with the capability of nucleolin-targeting and doulble wavelength fluorescences located at visible and near infreared range respectively. The optical properties, drug-loading efficiency and in vitro stability will be improved by optimizing the coupling efficiency and drug loading method. Based on the bio-evaluation of the nanocomposites including tumor cell affinity, cytotoxicity and in vivo toxicity,the application of the nano-composites in real time tracing and their tumor-targeting ability will also be evaluated. Furthermore, the anti-cancer activity of DOX@Au-APT-MPA will be estimated qualitatively and quantitatively both at cell level and animal level. Although nuclear targeting by peptide-modified nanoparticles has seen some success and shown improved anticancer efficacy, the mechanism responsible for the increased cell death is unknown because no nanoscale direct visualization of how the nanoparticles affected the nucleus was shown. The inter-celluar action of DOX@Au-APT-MPA and their influence on nucleus will also be investigated to elucidate the anti-cancer mechanism of the nano-composites, which will mainly depend on directly visualizing the interaction between a drug-loaded nanoconstruct and the cancer cell nucleus and correlating the resulting morphological deformations in nucleus with increased efficacy. The implementation of the project will provide new ideas for developing the integrated system of tumor-targeting imaging, real time diagnosis and therapy evaluation, which will also provide basis for researching the anti-cancer mechnism for these nano-composites.

多功能型纳米药物系统是现代纳米技术、药学、分子影像学及分子生物学融合而产生的一种新型药物载体，它兼具靶向、显像，表面可修饰性、生物相容性、抗肿瘤活性等显著特点。本项目拟以红色荧光金纳米簇为基础，构筑具有核仁素靶向，兼具可见及近红外荧光特性的载药纳米复合物DOX@Au-APT-MPA。通过优化纳米复合物的偶联效率与载药方法，提高其光学特性、载药效率及体外稳定性。对未载药纳米复合物进行生物学评价（肿瘤细胞亲和性、体内外毒性）的基础上，考察其用于体内示踪的可行性，评价其对肿瘤的靶向能力。进一步，分别于细胞水平及动物水平考察DOX@Au-APT-MPA的抗肿瘤活性（定性、定量）；并研究纳米复合物与细胞核的作用机制及对细胞核的影响，最终力求阐明该纳米复合物的抗肿瘤机理。该课题的实现将为可为我们开发肿瘤分子靶向、实时诊断和疗效评估的一体化系统提供新的思路，也为研究该类纳米复合物的抗肿瘤药效提供依据。

目前癌症治疗方法主要有手术、放疗和化疗，以上方法对正常细胞也有很大的杀伤作用，易引起很强的毒副作用，因此亟需研发对肿瘤细胞具有被动或主动靶向能力的治疗剂或其他可以降低毒副作用的治疗方案。基于纳米技术开发的癌症治疗方法可以达到局部靶向治疗，从而大大降低了毒副作用，提高了患者的生存率。由金纳米材料介导的光热治疗在动物水平的试验以及早期临床试验中取得了显著的效果，是非常具有前景的肿瘤治疗方案。. 本课题基于金纳米簇，通过还原法制备了粒径在3.06 nm左右的金纳米簇，通过选择具有高特异性的配体对金纳米簇进行表面修饰，并且偶联临床有效的化疗药物，金纳米簇既可以作为肿瘤诊断的信号分子，也为化疗药物的递送提供纳米平台，从而得到了基于金纳米簇的双靶向载药系统。进一步对其体内外理化性质、光学特性、靶向性等进行探索，对纳米药物的体内外治疗效果、深层组织渗透能力进行了验证。. 该纳米载药系统主要有以下优势：第一，金纳米簇的合成方法简易，且荧光性质稳定，易于通过荧光性质来定量；第二，金纳米簇的尺寸可控且在5 nm以下，既具有EPR效应可被动靶向至肿瘤部位，又因尺寸较小可渗透进入肿瘤深部组织，增强治疗剂的抗肿瘤效果；第三，金纳米簇的表面富有活性功能基团，适用于配体修饰；第四，环肽RGD和适配体修饰的载药体系可以实现血管-细胞膜-细胞核的传递，显著增强抗肿瘤效果。该课题的实现将为可为我们开发肿瘤分子靶向、实时诊断和疗效评估的一体化系统提供新的思路，也为研究该类纳米复合物的抗肿瘤药效提供依据。