Sustained Redox Photodynamic Therapy via Supramolecular Charge Separation of a Redox-active Dye

Photodynamic therapy (PDT) offers a minimally invasive strategy for cancer treatment, yet its clinical impact is limited by oxygen dependence and the inherently burst-type nature of reactive oxygen species (ROS) generation.Emerging Type I photosensitizers address oxygen scarcity through radical formation, but their activity remains transient due to rapid radical quenching and limited capacity for sustained redox-cycling activity.Here, we report a supramolecular photosensitizer based on the redox-active carbenium dye dimethoxyquinacridinium (DMQA + ) that enables sustained radical phototherapy with catalytic-like, repetitive redox activity.Selfassembly triggers symmetry-breaking charge-separation upon photoexcitation and stabilizes a long-lived charge-separated state, enabling repetitive photoredox turnover and sustained radical generation through multi-cycle redox activity driven by light and endogenous reductant consumption.This supramolecular state markedly enhances PDT efficacy compared to the monomeric Type II photosensitizer and retains potency even under hypoxia.These findings establish a design principle that shifts PDT from one-shot ROS dosing toward spatially confined redox stress, providing a framework for hypoxia-tolerant phototherapy and expanding the therapeutic scope of supramolecular medicine.