Key Laboratory of Flexible Electronics (KLOFE) & Institute of Advanced Materials (IAM), Nanjing Tech University (NanjingTech), Nanjing, 211816, P. R. China.
State Key Laboratory of Coordination Chemistry, Nanjing University, Nanjing, 210023, P. R. China.
Adv Healthc Mater. 2022 Jul;11(14):e2200400. doi: 10.1002/adhm.202200400. Epub 2022 May 6.
Nitroreductase (NTR), a common enzymatic biomarker of hypoxia, is widely used to evaluate tumor microenvironments. To date, numerous optical probes have been reported for NTRs detection. Approaches capable of concisely guiding the probe design of NTRs suitable for deep-tissue imaging, however, are still lacking. As such, direct optical imaging of endogenous NTR activities from tumors derived from cancer patients is thus far not possible. Herein, aided by computational calculations, the authors have successfully developed a series of two-photon (TP) small-molecule fluorogenic probes capable of sensitively detecting general NTR activities from various biological samples; by optimizing the distance between the recognition moiety and the reactive site of NTRs from different sources, the authors have discovered and experimentally proven that X4 displays the best performance in both sensitivity and selectivity. Furthermore, X4 shows excellent TP excited fluorescence properties capable of directly monitoring/imaging endogenous NTR activities from live mammalian cells, growing zebrafish, and tumor-bearing mice. Finally, with an outstanding TP tissue-penetrating imaging property, X4 is used, for the first time, to successfully detect endogenous NTR activities from the liver lysates and cardia tissues of a cancer patient. The work may provide a universal strategy to design novel TP small-molecule enzymatic probes in future clinical applications.
硝基还原酶（NTR）是缺氧的常见酶生物标志物，广泛用于评估肿瘤微环境。迄今为止，已经报道了许多用于检测 NTR 的光学探针。然而，能够简洁地指导适合深层组织成像的 NTR 探针设计的方法仍然缺乏。因此，直接从癌症患者来源的肿瘤中对内源性 NTR 活性进行光学成像目前仍然无法实现。在此，在计算计算的辅助下，作者成功开发了一系列可灵敏检测来自各种生物样本的通用 NTR 活性的双光子（TP）小分子荧光探针；通过优化来自不同来源的 NTR 的识别部分和反应部位之间的距离，作者发现并通过实验证明 X4 在灵敏度和选择性方面表现最佳。此外，X4 表现出出色的 TP 激发荧光特性，能够直接监测/成像活哺乳动物细胞、生长的斑马鱼和荷瘤小鼠中的内源性 NTR 活性。最后，凭借出色的 TP 组织穿透成像特性，X4 首次成功地从癌症患者的肝裂解物和心脏组织中检测到内源性 NTR 活性。这项工作可能为未来临床应用中设计新型 TP 小分子酶探针提供一种通用策略。
