GSH/pH Dual Activatable Cross‐linked and Fluorinated PEI for Cancer Gene Therapy Through Endogenous Iron De‐Hijacking and in Situ ROS Amplification

Abstract Ferroptosis‐related cancer therapy is limited by insufficient Fe²⁺/Fe³⁺ redox pair and hydrogen peroxide (H₂O₂) for producing lethal hydroxyl radicals (·OH). Although exogenous iron or ROS‐producing drugs can enhance ferroptosis, exploiting endogenous iron (labile iron pool, LIP) stored in ferritin and promoting ROS generation may be safer. Herein, a metal/drug‐free nanomedicine is developed for responsive LIP release and H₂O₂ generation on the mitochondria membranes, amplifying hydroxyl radical production to enhance ferroptosis‐mediated antitumor effects. A glutathione(GSH)/pH dual activatable fluorinated and cross‐linked polyethyleneimine (PEI) with dialdehyde polyethylene glycol layer nanocomplex loaded with MTS‐KR‐SOD (Mitochondria‐targeting‐sequence‐KillerRed‐Superoxide Dismutase) and CRISPR/Cas9‐CA IX (Carbonic anhydrase IX (CA IX)) plasmids (FP@MC) are developed for enhanced ferroptosis through endogenous iron de‐hijacking and in situ ROS amplification. Two plasmids are constructed to knockdown CA IX and translate KillerRed‐SOD recombinant protein specifically on mitochondria membranes, respectively. The CA IX knockdown acidifies the intracellular environment, leading the release of LIP from ferritin as a “flare” to initiate endogenous chemodynamic therapy. Meanwhile, MTS‐KR‐SOD generates H₂O₂ when irradiated by a 590 nm laser to assist chemodynamic therapy, leading to ROS amplification for mitochondria damage and lipid peroxide accumulation. The combined therapeutic effects aggravate cancer ferroptosis and suppress tumor growth, providing a new paradigm for amplifying ROS and iron ions to promote ferroptosis‐related cancer therapy.