State Key Laboratory of Fine Chemicals, Frontiers Science Center for Smart Materials Oriented Chemical Engineering, Dalian University of Technology, No. 2 Linggong Road, Dalian, 116024, China.
Liaoning Binhai Laboratory, Dalian, 116023, China.
Nat Commun. 2024 Aug 13;15(1):6935. doi: 10.1038/s41467-024-51253-5.
Nanobodies (Nbs), the smallest antigen-binding fragments with high stability and affinity derived from the variable domain of naturally occurring heavy-chain-only antibodies in camelids, have been shown as an efficient way to improve the specificity to tumors for photodynamic therapy (PDT). Nonetheless, the rapid clearance of Nbs in vivo restricts the accumulation and retention of the photosensitizer at the tumor site causing insufficient therapeutic outcome, especially in large-volume tumors. Herein, we develop photodynamic conjugates, MNB-Pyra Nbs, through site-specific conjugation between 7D12 Nbs and type I photosensitizer MNB-Pyra (morpholine-modified nile blue structure connected to pyrazolinone) in a 1:2 ratio. The photosensitizers with long-term retention can be released at the tumor site by reactive oxygen species cleavage after illumination, accompanied with fluorescence recovery for self-reporting the occurrence of PDT. Ultimately, a single dose of MNB-Pyra Nbs demonstrate highly effective tumor suppression with high biosafety in the large-volume tumor models after three rounds of PDT. This nanobody conjugate provides a paradigm for the design of precise long-time retention photosensitizers and is expected to promote the development of PDT.
纳米抗体（Nbs）是从小型骆驼科动物天然存在的重链抗体的可变区衍生而来的最小抗原结合片段，具有高稳定性和亲和力，已被证明是提高光动力疗法（PDT）对肿瘤特异性的有效方法。然而，Nbs 在体内的快速清除限制了光敏剂在肿瘤部位的积累和保留，导致治疗效果不足，尤其是在大容量肿瘤中。在此，我们通过 7D12 Nbs 与 I 型光敏剂 MNB-Pyra（连接吡唑啉酮的吗啉修饰的尼罗河蓝结构）在 1:2 的比例下进行特异性连接，开发了光动力偶联物 MNB-Pyra Nbs。在光照后，通过活性氧的裂解可以将具有长期保留能力的光敏剂释放到肿瘤部位，同时伴随着荧光恢复，用于自我报告 PDT 的发生。最终，在三轮 PDT 后，单次剂量的 MNB-Pyra Nbs 在大容量肿瘤模型中表现出高度有效的肿瘤抑制作用，且具有较高的生物安全性。该纳米抗体偶联物为精确的长效保留光敏剂的设计提供了范例，有望促进 PDT 的发展。
