A Self-Assembling Chimeric Peptide Gear-Set with "Three-in-One" Function for Precision Photodynamic Therapy.

Smart drug delivery systems that activate in response to tumor-specific signals and include real-time monitoring are highly desirable in personalized cancer treatment. Herein, a new chimeric peptide, PpIX-1-DG, is designed with an integrated "gear set" mechanism for achieving auto-activation, cascade-amplification and self-reporting features in precision photodynamic therapy. The peptide, comprised of a photosensitizer and a gemcitabine prodrug, self-assembles into nanoparticles in physiological condition. Upon cellular uptake, nanoparticles specifically respond to elevated GSH levels in cancer cells to release gemcitabine, thereby exerting its chemotherapeutic effect for initiating apoptosis and activating caspase-3-the first "auto-activation" gear. Next, caspase-3 catalyzes the production of photosensitive PpIX-1, resulting in elevation of intracellular ROS in A549 cells, thereby inducing mitochondrial dysfunction and more apoptosis upon photoirradiation. This process elevates caspase-3 levels and activates additional photosensitizers, marking the second "cascade amplification" gear. Intravenous administration of PpIX-1-DG alongside photoirradiation shows enhanced antitumor efficacy and minimal systemic toxicity. Notably, the fluorescence of PpIX-1-DG activated by caspase-3 facilitates real-time monitoring, enabling the third "self-reporting" gear for therapeutic outcome tracking in vitro and in vivo. Together, this "three-in-one" strategy enables precision photodynamic therapy and synchronous therapeutic monitoring, holding great potential in the realm of cancer nanomedicine. STATEMENT OF SIGNIFICANCE: This study presents a self-assembled chimeric peptide nanoplatform (PpIX-1-DG NPs) that integrates a 'three-in-one' mechanism, enabling auto-activation, cascade amplification, and self-reporting functions for precision photodynamic therapy while allowing real-time monitoring of treatment efficacy. In GSH-rich tumor microenvironment, the peptide specifically releases gemcitabine, which triggers the activation of caspase-3. This enzyme cleaves a DEVD linker in the peptide molecule, thereby activating the photosensitive PpIX-1. The activated PpIX-1 then generates reactive oxygen species (ROS) upon photoirradiation, triggering more cells undergoing apoptosis and ferroptosis. Meanwhile, the fluorescence emitted from activated PpIX-1 allows dynamic tracking of treatment efficacy. We believe this approach offers a new paradigm for improving treatment outcomes and therapeutic monitoring over a variety of diseases.