The synthesis, fluorogenic characterization, and labeling application of four tetrazine-quenched cyanine probes with emission maxima in the red–far red range is reported. Fluorescence of the cyanine-cores is quenched via through-bond-energy-transfer (TBET) exerted by a bioorthogonal tetrazine unit. Upon bioorthogonal labeling reaction with cyclooctyne tagged proteins, the quenching effect ceases, and thus the fluorescence reinstates, resulting in an increase in fluorescence intensity. As a rare example among indocyanines, one of our new probes was found suitable in STED-based super-resolution imaging. The applicability of this fluorogenic Tet-Cy3 probe was therefore further demonstrated in the bioorthogonal labeling of cytoskeletal protein, actin, with subsequent super-resolution microscopy (STED) imaging even under no-wash conditions.

中文翻译：

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生物正交适用的氟菁菁-四嗪用于无清洗超分辨率成像

报道了四种四嗪淬灭的花青探针的合成，荧光表征和标记应用，其发射最大值在红-远红范围内。通过键能量转移淬灭花青核心的荧光（TBET）由生物正交四嗪单元发挥作用。与环辛炔标记的蛋白质进行生物正交标记反应后，淬灭作用停止，因此荧光恢复，导致荧光强度增加。作为吲哚菁中的一个罕见实例，我们发现其中一种新探针适用于基于STED的超分辨率成像。因此，该荧光Tet-Cy3探针的适用性在细胞骨架蛋白肌动蛋白的生物正交标记中得到了进一步证明，甚至在不清洗条件下，其后的超分辨率显微镜（STED）成像也得到了证实。