Polypeptide-Based Theranostics with Tumor-Microenvironment-Activatable Cascade Reaction for Chemo-ferroptosis Combination Therapy.

Nanoengineering of polymer-based therapeutic carriers is promising for precise cancer treatment. Herein, we report the fabrication of polypeptide vehicles encapsulated with anticancer drug of cisplatin (Pt drug) and Fe3O4 nanoparticles (denoted as Pt&Fe3O4@PP) as theranostics for T2-weighted magnetic resonance imaging (MRI)-guided chemo-ferroptosis combination therapy. The number of Fe3O4 nanoparticles per polypeptide vehicle is well controlled by adjusting the added amount of Fe3O4 nanoparticles. The tumor microenvironment can trigger the release of Pt drug and Fe2/3+, which could induce the intracellular cascade reaction to generate sufficient •OH for ferroptosis therapy. Moreover, the released Pt drug can cause the apoptosis of tumor cells. Meanwhile, the encapsulated Fe3O4 nanoparticles can also be used for T2-weighted MRI of tumor. Both in vitro and in vivo results indicate that the reported Pt&Fe3O4@PP can efficiently inhibit cancer cell growth without causing significant systemic toxicity. Importantly, polypeptide vehicles could significantly reduce the side effect of free Pt drug in vivo and therefore improve the drug delivery efficacy. Our findings suggest that polypeptide-based theranostics with tumor-microenvironment-activatable cascade reaction have great potential in biomedical applications.