Wang Kang-Nan, Cao Qian, Liu Liu-Yi, Zhao Zi-Jian, Liu Wenting, Zhou Dan-Jie, Tan Cai-Ping, Xia Wei, Ji Liang-Nian, Mao Zong-Wan
MOE Key Laboratory of Bioinorganic and Synthetic Chemistry , School of Chemistry , Sun Yat-sen University , Guangzhou , 510275 , P. R. China . Email:
Chem Sci. 2019 Sep 6;10(43):10053-10064. doi: 10.1039/c9sc03594j. eCollection 2019 Nov 21.
Although fluorescence tracing of small bioactive molecules in living cells has been extensively studied, it is still a challenging task to detect their variations in the nucleus mainly due to the impermeable nuclear membrane and nucleic acid interference. Herein, we take advantage of the nucleic acid enriched environment in the nucleus to establish a strategy, named "charge-driven tripod somersault on DNA", for ratiometric fluorescence imaging of small bioactive molecules in the nucleus. Taking SO derivatives as a typical target analyte, a tripodal probe has been constructed by conjugating two DNA binding groups containing a SO derivative reaction site. Mechanism studies demonstrate that upon encountering and reacting with SO /HSO , a charge variation occurs at the responsive arm of the tripodal probe, triggering a tripod somersault on DNA, resulting in the conformational rearrangement of the DNA binding modes with DNA-modulated fluorescence change, which allows the second emission feature to emerge. In this strategy, probe-DNA binding is not influenced by RNA or non-specific protein association, thus making it ideal for tracing nucleus-localized analytes. The application of this strategy has realized both and ratiometric fluorescence imaging of the variations of endogenous SO derivatives in the nucleus for the first time, with high specificity and selectivity. Also, in theory, this strategy opens up a new avenue for the design of fluorescence probes for the nucleus-localized biological analytes.
尽管对活细胞中小生物活性分子的荧光追踪已进行了广泛研究，但由于核膜的不可渗透性和核酸干扰，检测它们在细胞核中的变化仍然是一项具有挑战性的任务。在此，我们利用细胞核中富含核酸的环境，建立了一种名为“DNA上的电荷驱动三脚架翻转”的策略，用于对细胞核中的小生物活性分子进行比率荧光成像。以SO衍生物作为典型的目标分析物，通过共轭两个含有SO衍生物反应位点的DNA结合基团构建了一种三脚架探针。机理研究表明，当三脚架探针与SO /HSO 相遇并发生反应时，其响应臂上会发生电荷变化，触发DNA上的三脚架翻转，导致DNA结合模式的构象重排，伴随DNA调制的荧光变化，从而使第二个发射特征出现。在该策略中，探针与DNA的结合不受RNA或非特异性蛋白质结合的影响，因此非常适合追踪细胞核定位的分析物。该策略的应用首次实现了对细胞核内源性SO衍生物变化的比率荧光成像，具有高特异性和选择性。此外，从理论上讲，该策略为设计用于细胞核定位生物分析物的荧光探针开辟了一条新途径。
