Mitochondria-targeted peptide-engineered bimetallic nanozymes enable ferroptosis-sensitized cuproptosis for melanoma therapy

ABSTRACT Developing nanotherapeutics to circumvent intrinsic apoptosis resistance in cancer remains a key challenge in oncology. Cuproptosis, a non-apoptotic cell death modality, has emerged as a promising alternative, yet its therapeutic efficacy is frequently limited by robust intracellular antioxidant defense systems. Here, we developed an ultrasmall (∼10 nm) mitochondria-targeted bimetallic nanozyme (RMOCZ) for synergistic ferroptosis-cuproptosis therapy against malignant melanoma. The Cu/Zn bimetallic core, functionalized with a chimeric mitochondrial targeting peptide, serves as both a pH-responsive copper reservoir and a dual-enzyme mimetic (peroxidase and glutathione oxidase). Upon endolysosomal acidification, RMOCZ disassembles to co-release copper ions and oridonin (ORI). The nanozyme oxidizes intracellular glutathione (GSH), a process significantly accelerated by co-delivered ORI. This disruption of redox homeostasis not only triggers ferroptosis by compromising cellular antioxidant capacity but also amplifies peroxidase-mediated reactive oxygen species (ROS) production, sensitizing tumor cells to copper-induced cytotoxicity. Concurrently, RMOCZ induces ferritinophagy to mobilize the endogenous labile iron pool and exacerbate lipid peroxidation. These events culminate in sustained copper-iron dual-ion overload. Following subsequent mitochondrial trafficking, the accumulated copper ions trigger canonical cuproptotic events, including the degradation of iron-sulfur (Fe-S) clusters and aberrant oligomerization of lipoylated DLAT. This irreversible mitochondrial dysfunction triggers potent immunogenic cell death (ICD) with robust DAMPs release. In situ immunohistochemical analyses confirm that this RMOCZ-induced ICD profoundly remodels the immunosuppressive microenvironment, promoting CD86 + antigen-presenting cell maturation and enhancing intratumoral infiltration of CD3 + and CD8 + T cells. In vivo, RMOCZ demonstrates substantial melanoma regression with negligible systemic toxicity, providing a promising strategy for treating apoptosis-resistant refractory malignancies.