A spirocyclic BODIPY photosensitizer with pH-triggered triplet-state activation for tumor-selective photodynamic therapy

Conventional PDT photosensitizers generally suffer from inherent poor tumor selectivity. We herein develop a novel spirocyclic BODIPY-based photosensitizer (BDP-I) to exploit the weakly acidic tumor microenvironment for targeted selective activation. It enables efficient pH-triggered triplet-state ROS restoration and prominent tumor-selective phototoxicity, providing a promising molecular scaffold for precise tumor-acidity-targeted PDT.