Division of Surgery and Interventional Science, University College London, Royal Free Campus, Rowland Hill Street, London, NW3 2PE, UK.
Department of Pharmacy and Pharmacology, University of Bath, Bath, BA2 7AY, UK.
Sci Rep. 2017 Jul 20;7(1):6059. doi: 10.1038/s41598-017-06109-y.
A major problem with many promising nano-sized biotherapeutics including macromolecules is that owing to their size they are subject to cellular uptake via endocytosis, and become entrapped and then degraded within endolysosomes, which can significantly impair their therapeutic efficacy. Photochemical internalisation (PCI) is a technique for inducing cytosolic release of the entrapped agents that harnesses sub-lethal photodynamic therapy (PDT) using a photosensitiser that localises in endolysosomal membranes. Using light to trigger reactive oxygen species-mediated rupture of the photosensitised endolysosomal membranes, the spatio-temporal selectivity of PCI then enables cytosolic release of the agents at the selected time after administration so that they can reach their intracellular targets. However, conventional photosensitisers used clinically for PDT are ineffective for photochemical internalisation owing to their sub-optimal intracellular localisation. In this work we demonstrate that such a photosensitiser, chlorin e, can be repurposed for PCI by conjugating the chlorin to a cell penetrating peptide, using bioorthogonal ligation chemistry. The peptide conjugation enables targeting of endosomal membranes so that light-triggered cytosolic release of an entrapped nano-sized cytotoxin can be achieved with consequent improvement in cytotoxicity. The photoproperties of the chlorin moiety are also conserved, with comparable singlet oxygen quantum yields found to the free chlorin.
许多有前途的纳米级生物治疗药物（包括大分子）存在一个主要问题，由于它们的尺寸，它们会通过内吞作用被细胞摄取，并在内溶酶体中被捕获和降解，这会显著降低它们的治疗效果。光化学内化（PCI）是一种诱导被捕获药物胞质释放的技术，它利用一种定位于内溶酶体膜中的光敏剂来进行亚致死光动力疗法（PDT）。使用光来触发活性氧介导的光敏内溶酶体膜破裂，然后 PCI 的时空选择性使得在给药后选择的时间进行胞质释放药物，以便它们能够到达其细胞内靶标。然而，临床上用于 PDT 的传统光敏剂由于其细胞内定位不佳而不适用于光化学内化。在这项工作中，我们证明了通过使用生物正交连接化学将氯连接到细胞穿透肽上，可以将这样的光敏剂，即叶绿素 e，重新用于 PCI。肽缀合能够靶向内体膜，从而可以实现用光触发的被捕获的纳米级细胞毒素的胞质释放，从而提高细胞毒性。氯部分的光物理性质也得到了保留，与游离的氯相比，发现具有相当的单线态氧量子产率。
