基于CHA反应的框架核酸传感平台用于肿瘤微环境中ATP的可视化成像研究

肿瘤微环境中细胞外的ATP浓度比正常组织细胞外ATP的含量高1000-10000倍，因此过高浓度的ATP可以作为诊断癌症的生物标志物。本项目针对大多数的传统方法无法实现肿瘤微环境中ATP的原位传感问题，结合框架核酸优异的生物相容性及催化发夹自组装（CHA）反应的信号扩增特点，开发对肿瘤微环境中ATP原位传感的新方法。我们以胆固醇修饰的四面体框架核酸作为脚手架，连接CHA信号放大探针，构建锚定于肿瘤细胞表面的ATP原位可视化成像平台。在肿瘤细胞外高浓度ATP的作用下，框架核酸于肿瘤细胞表面发生原位多级交联，形成纵横交错的新颖“网状核酸”结构，可通过荧光共振能量转移（FRET）技术对ATP放大信号进行可视化读出。该项目的实施将有助于从分子水平上阐明肿瘤微环境中的ATP在癌症发展及肿瘤转移中的作用，在与ATP水平异常相关的癌症早期诊断、药物靶向递送及治疗癌症新方法开发等方面具有重要的临床意义。

The extracellular ATP concentration in the tumor microenvironment is 1000-10000 times higher than that in normal tissues. Therefore, excessively high concentrations of ATP can be used as biomarkers for the cancer diagnosis. Based on the fact that traditional methods are unable to in-situ sense ATP in the tumor microenvironment, we plan to develop a novel method by integrating the excellent biocompatibility of the framework nucleic acids and the signal amplification feature of the catalyzed hairpin assembly (CHA) reaction for in-situ ATP sensing in the tumor microenvironment. To construct a platform anchored onto the surface of tumor cells for in-situ imaging ATP, we utilize cholesterol-modified tetrahedral framework nucleic acids as the scaffold to link with CHA signal amplification probes. Triggered by the high concentrations of ATP outside of tumor cells, the tetrahedral framework nucleic acids undergo in-situ multi-stage cross-linking processes, eventually forming a novel “reticulated nucleic acids” structure crisscrossed on the cell surface. Thus, the amplified ATP signal can be visually read by fluorescence resonance energy transfer (FRET). The implementation of this project will help us to understand the role of ATP in the tumor microenvironment. Furthermore, this project shows great significance for abnormal ATP levels-related cancer early diagnosis, drug delivery, and development of new methods for cancer treatment.