School of Chemistry, Chemical Engineering and Biotechnology, Nanyang Technological University, 70 Nanyang Drive, Singapore 637457, Singapore.
National Engineering Research Centre for Nanomedicine, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan 430074, P. R. China.
J Am Chem Soc. 2024 Jun 26;146(25):17393-17403. doi: 10.1021/jacs.4c05012. Epub 2024 Jun 11.
Dual-locked activatable optical probes, leveraging the orthogonal effects of two biomarkers, hold great promise for the specific imaging of biological processes. However, their design approaches are limited to a short-distance energy or charge transfer mechanism, while the signal readout relies on fluorescence, which inevitably suffers from tissue autofluorescence. Herein, we report a long-distance singlet oxygen transfer approach to develop a bienzyme-locked activatable afterglow probe (BAAP) that emits long-lasting self-luminescence without real-time light excitation for the dynamic imaging of an intratumoral granule enzyme. Composed of an immuno-biomarker-activatable singlet oxygen (O) donor and a cancer-biomarker-activatable O acceptor, BAAP is initially nonafterglow. Only in the presence of both immune and cancer biomarkers can O be generated by the activated donor and subsequently diffuse toward the activated acceptor, resulting in bright near-infrared afterglow with a high signal-to-background ratio and specificity toward an intratumoral granule enzyme. Thus, BAAP allows for real-time tracking of tumor-infiltrating cytotoxic T lymphocytes, enabling the evaluation of cancer immunotherapy and the differentiation of tumor from local inflammation with superb sensitivity and specificity, which are unachievable by single-locked probes. Thus, this study not only presents the first dual-locked afterglow probe but also proposes a new design way toward dual-locked probes via reactive oxygen species transfer processes.
双锁激活光学探针利用两种生物标志物的正交效应，有望实现对生物过程的特异性成像。然而，其设计方法仅限于短距离能量或电荷转移机制，而信号读出依赖于荧光，这不可避免地受到组织自发荧光的影响。在此，我们报告了一种长距离单线态氧转移方法，开发了一种双酶锁定激活后发光探针（BAAP），该探针在没有实时光激发的情况下发出持久的自发光，用于肿瘤内颗粒酶的动态成像。BAAP 由免疫生物标志物激活的单线态氧（O）供体和癌症生物标志物激活的 O 受体组成，最初是非后发光的。只有在存在免疫和癌症生物标志物的情况下，才能通过激活的供体产生 O，然后 O 向激活的受体扩散，从而产生具有高信噪比和特异性的近红外强后发光，用于肿瘤内颗粒酶。因此，BAAP 可以实时跟踪肿瘤浸润的细胞毒性 T 淋巴细胞，能够评估癌症免疫疗法，并以优异的灵敏度和特异性区分肿瘤与局部炎症，这是单锁探针无法实现的。因此，本研究不仅提出了第一个双锁后发光探针，还通过活性氧转移过程提出了一种设计双锁探针的新方法。
