Tumor Microenvironment Cascade‑Responsive Nanodrug with Self‑Targeting Activation and ROS Regeneration for Synergistic Oxidation‑Chemotherapy

Carrier-free nanodrug with exceptionally high drug payload has attracted increasing attentions.Herein,we construct a pH/ROS cascade-responsive nanodrug which could achieve tumor acidity-triggered targeting activation followed by circularly amplified ROS-triggered drug release via positive-feedback loop.The di-selenide-bridged prodrug synthesized from vitamin E succinate and methotrexate(MTX)self-assembles into nanoparticles(VSeM);decorating acidity-cleavable PEG onto VSeM surface temporarily shields the targeting ability of MTX to evade immune clearance and consequently elongate circulation time.Upon reaching tumor sites,acidity-triggered detachment of PEG results in targeting recovery to enhance tumor cell uptake.Afterward,the VSeM could be dissociated in response to intracellular ROS to trigger VES/MTX release;then the released VES could produce extra ROS to accelerate the collapse of VSeM.Finally,the excessive ROS produced from VES could synergize with the released MTX to efficiently suppress tumor growth via orchestrated oxidation-chemotherapy.Our study provides a novel strategy to engineer cascade-responsive nanodrug for synergistic cancer treatment.