Modular Engineering of Enzyme‐Activatable DNA Nanodevices for Endoplasmic Reticulum‐Targeted Photodynamic Antitumor Therapy

Abstract Endoplasmic reticulum (ER)‐targeted photodynamic therapy (PDT) has garnered wide attention for its potential to improve tumor treatment outcomes. However, achieving spatially selective control over the activation of photosensitizers (PSs) within the ER remains a major challenge. In this study, a programmable DNA nanodevice, termed EDEP, designed for targeted delivery and localized activation of PSs, thereby achieving ER‐specific activatable tumor therapy, is presented. This modular engineered DNA nanodevice comprises an enzyme‐activatable, DNA‐based PS (ED), a nanocarrier and an ER‐targeting ligand, allowing it to accumulate specifically within the ER lumen. The ED features a unique enzyme‐responsive turn‐on mechanism that selectively activates the PS upon interaction with an enzyme, facilitating controlled reactive oxygen species (ROS) generation at the targeted subcellular site. It is demonstrated that EDEP enables selective ROS production in the ER, leading to significant cytotoxicity in tumor cells. Furthermore, this nanodevice induces mitochondrial permeability transition pore opening, resulting in mitochondrial dysfunction and amplified tumor cell death. This work presents an enzyme‐controlled, ER‐targeted PDT strategy that holds promise for precise cancer therapy.