Previous studies have demonstrated that induction of reactive oxygen species (ROS) significantly enhances the cytotoxicity of paclitaxel (Ptx). Tetrandrine (Tet), a potent ROS inducer, synergistically enhances the antitumor effects of Ptx. To codeliver Ptx and Tet, which have low solubility, high systemic toxicity, and poor tumor selectivity, we designed a tumor microenvironment-activatable prodrug-based delivery system. A ROS-responsive prodrug was developed by the conjugation of Ptx to a biocompatible polymer (1,2-distearoyl--glycero-3-phosphoethanolamine-poly(ethylene glycol), DSPE-PEG) via the ROS-cleavable thioketal (TK) linker, which could self-assemble into core-shell nanoparticles with Tet in the inner core to form redox-responsive Ptx/Tet-coloaded nanoparticles (P/T-NPs). The synergistic anticancer mechanism of Ptx and Tet was systematically investigated by cytotoxicity assays, ROS detection, mitochondrial tracing, transmission electron microscopy, and bothandexperiments. Cell uptake of P/T-NPs increased in a time-dependent manner, with partial accumulation observed in the mitochondria. The targeted release of Tet in tumor sites with high ROS levels could further elevate intracellular ROS, which in turn accelerated the cleavage of the TK linker and promoted the release of Ptx, thereby enhancing its antitumor effect. P/T-NPs showed superior cytotoxicity, which is strongly correlated to the superior autophagy-inducing ability of P/T-NPs. Moreover, P/T-NPs effectively inhibit the tumor growth compared to either the free drug or their combination therapy. This study integrates tumor microenvironment activation, self-amplified drug release, and ROS-enhanced chemotherapy into a single nanoplatform, offering a promising strategy for targeted cancer therapy. sn in vitro in vivo
