【摘要】 四面体框架核酸是由四条单链DNA基于碱基互补配对原则自组装形成的拓扑结构，具有细胞毒性低、无需转染试剂辅助进入细胞等优点，常被用于活细胞内mRNA的检测。四面体框架核酸进入细胞并遇到靶标mRNA，将发生靶标识别作用，难以控制反应起点，使得在特定时间点检测活细胞内的mRNA分布成为挑战。本研究设计了光敏四面体框架核酸用于细胞内mRNA的高时空可控检测。在未经紫外光照时，光敏四面体框架核酸处于“潜伏”状态，不能识别靶标mRNA；在紫外光激活下，此探针中的光响应分子被切断，暴露出Toehold结构，引发靶标mRNA与光敏四面体框架核酸发生链取代反应，产生强荧光信号。通过优化光照时间，可实现溶液中低至1 nmol/L的靶标DNA检测，以及活细胞内mRNA的高时空可控检测。更多还原

【Abstract】 Tetrahedral framework nucleic acids(tFNAs)are topological structures formed by the self-assembled four single-stranded DNA based on the specific base pairing. t FNAs have low cytotoxicity and can enter into cells without the need of transfection agents, and thus have been used for mRNA detection in living cells. However, once they enter into cells and meet the target mRNA, the target recognition reaction will happen, which makes it challenging to control the start point of reaction and detect m RNA in living cells at desired time. To circumvent this issue, in this work, a photoresponsive tFNA was designed for mRNA detection in living cells with high spatiotemporal control. Without UV irradiation, the photoresponsive tFNA was in an unawakened state and could not recognize the target mRNA. While upon the UV activation, the photoresponsive linker in the tFNA was cleaved,causing the exposure of toehold. Then, the target mRNA could hybridize with the t FNA by toehold-mediated strand displacement reaction, leading to an increase of fluorescence. By optimizing the illumination time, the photoresponsive t FNA could detect as low as 1 nmol/L of target DNA in solution, and could detect target mRNA in living cells with high spatiotemporal control.更多还原