近红外二区小分子染料的功能化修饰及其在肿瘤诊疗中的应用

Fluorescence in the second near-infrared window (NIR-II) has the characteristics of probing tissue at centimeter depths and good signal-noise ratio in imaging of biological systems. Moreover, NIR-II imaging gave higher tumor-to-normal tissue (T/NT) ratio than traditional NIR-I imaging, allowing accurate image-guided tumor-removal surgery. However, few small molecule dyes in NIR-II was evaluated in imaging study. Herein, we developed functional modified small molecule dyes in NIR-II, which contained NIR-II fluorophore (CH1055, IR-1048, IR-1061, etc.), anticancer durg (capecitabine, doxifluridine, DOX, etc.) and targeting units (RGD, Biotin, RWR, etc.). These modified molecules can be activated by endogenously produced components (such as GSH, H2O2, cathepsin S, etc.) in tumor cells, and release drug to the tumor cells. Different linker groups would be optimized and evaluated by both in vitro and in vivo experiments to obtain the ideal prodrug based on small molecule dyes in NIR-II. The ideal modified molecule can be used to expound the activated mechanism and explore the relationships between NIR-II fluorescence signal and the concentrations of different activated components in cancer cells. The study of this relationship can be applied to recognition ad diagnosis of cancer cells. This research could also realize real-time monitoring of tumor during the targeted therapy and have great potential for the diagnosis and treatment of cancer.

近红外二区（NIR-II）荧光在活体影像研究中具有高组织穿透深度、高成像信噪比等优点。本项目将利用NIR-II小分子荧光基团的成像优势，结合其结构特点，对NIR-II小分子染料进行功能化改进，设计合成肿瘤细胞特异性活化的抗肿瘤NIR-II功能化分子，实现对肿瘤细胞的识别和靶向治疗。我们拟采用靶向性配体基团（如RGD、Biotin、RWR等）将功能化的NIR-II前药分子靶向至肿瘤组织，然后被肿瘤细胞内高浓度的活化因素（如GSH、H2O2、cathepsin S等）特异性激活，开启近红外二区荧光并释放出抗肿瘤药物。这种基于NIR-II小分子染料的功能化改进，既可用于探索肿瘤细胞NIR-II荧光信息与胞内活化因素含量的内在关联，实现对肿瘤细胞的识别和诊断分期；又可用于肿瘤靶向治疗过程中的在体实时监测，实现肿瘤边界的确定和精准手术的导航，为最终实现肿瘤诊疗一体化提供新思路。

恶性肿瘤仍然是危害人类健康的主要杀手，针对癌症的早期诊断及其治疗成为当前国际研究的热点。近红外二区（NIR-II）荧光在活体影像研究中具有高组织穿透深度、高成像信噪比等优点。本项目利用这一特点，首先合成了两大类12个针对肿瘤细胞内高浓度的GSH和H2O2敏感的抗肿瘤诊疗前药，并通过体外的灵敏度和选择性实验进行筛选，得到一个对肿瘤细胞进行良好靶向性和释药效率的前药分子GSH-1。该前药分子能通过靶向基团Biotin识别肿瘤细胞，在肿瘤细胞高表达的生物素受体介导下进入细胞内，被肿瘤细胞内高表达的GSH特异性活化释放抗肿瘤药物多西氟尿啶，同时近红外二区荧光团IR-1061也发出强烈的近红外二区荧光。在此筛选结果基础上，我们进一步对前药分子GSH-1的体内近红外二区成像和抗肿瘤活性进行评价。研究结果发现前药分子GSH-1不仅对生物素受体高表达的皮下瘤具有明显的肿瘤靶向性和近红外二区成像性，而且具有很好的抗肿瘤活性，显著增长小鼠存活期。本项目综合运用分子影像学与化学生物学技术，优选得到了一个可用于近红外二区成像的小分子抗肿瘤前药，实现了对肿瘤治疗过程的深层组织实时监测，为最终实现肿瘤诊疗一体化提供了新的思路。通过本课题的顺利实施，我们不仅扩展了NIR-II 小分子荧光染料在医学研究领域的应用，而且对前药分子的肿瘤成像和治疗一体化进行了深入研究，对于肿瘤的早期诊断和治疗具有非常重要的现实意义。