Redox-responsive dual-drug nanomedicine integrating cisplatin and trypsin for synergistic reversal of tumor chemoresistance.

To overcome cisplatin resistance without increasing systemic toxicity, we rationally elaborated a glutathione-activatable prodrug nanomedicine that chemically co-encapsulates cisplatin and a masked protease. First, a redox-labile succinimide linker (NC-ss-COOH) was covalently grafted onto the ε-amino groups of trypsin to create a "pro-protease" (ssTrypsin) whose catalytic activity is completely silenced in circulation but instantly restored (≥96%) upon cleavage by intratumoral GSH. Simultaneously, cisplatin was stably coordinated to the carboxyl-rich backbone of cRGD-PEG-polyglutamic acid and carboxyl-rich ssTrypsin, forming a polymer-Pt(II) prodrug that prevents premature Pt-GSH adduct formation. These two prodrugs co-self-assemble into potent anti-tumor nanoconstructs that actively target αvβ3/αvβ5-overexpressing tumors. Upon GSH-triggered activation, the dual-drug combination exerts complementary actions: (i) released cisplatin directly damages DNA, while (ii) reactivated trypsin proteolytically degrades all intracellular, cytomembrane, and extracellular proteins as possible (including DNA-repair proteins), collectively re-sensitizing resistant cells. This "prodrug + pro-enzyme" strategy yields a 2.5-fold reduction in IC50 against A2780DDP cells and 77% tumor suppression in vivo, all with minimal off-target toxicity.