Smart Tumor‐Cell‐Derived Microparticles Provide On‐Demand Photosensitizer Synthesis and Hypoxia Relief for Photodynamic Therapy

Abstract Positioning essential elements of photodynamic therapy (PDT) near to mitochondria can conquer the rigorous spatiotemporal limitations of reactive oxygen species (ROS) transfer and make considerable differences in PDT. However, precise accumulation of photosensitizer (PS) and oxygen within mitochondria is still challenging. We simultaneously encapsulated hexyl 5‐aminolevulinate hydrochloride (HAL) and 3‐bromopyruvic acid (3BP) into microparticles collected from X‐ray‐irradiated tumor cells (X‐MP). After systemic administration, the developed HAL/3BP@X‐MP can specifically target and recognize tumor cells, where HAL induces efficient accumulation of PpIX in mitochondria via the intrinsic haem biosynthetic pathway. Meanwhile, 3BP remarkably increases the oxygen supply by inhibiting mitochondrial respiration. The accurate co‐localization and prompt encounter of PpIX and oxygen produce sufficient ROS to directly disrupt mitochondria, resulting in significantly improved PDT outcomes.