Bioinspired miRNA-Responsive Ca ²⁺ Nanoregulator with Dual Interference Pathways and Self-Amplifying Cascade for Tumor-Targeted Mitochondrial Dysfunction

Disrupting mitochondrial calcium ion (Ca²⁺) homeostasis in tumor cells has emerged as a potent anticancer strategy, however, achieving precise, spatiotemporal control of mitochondrial Ca²⁺ overload poses a significant challenge. Herein, we present a bioinspired miRNA-responsive Ca²⁺ nanoregulator (Cu₂O@Dz) that orchestrates endogenous ion flux through a multistage cascade to induce tumor-specific mitochondrial dysfunction. In this design, hairpin-structured DNAzymes (Dz) are conjugated to cuprous oxide (Cu₂O) nanoparticles: within the acidic and H₂O₂-rich tumor microenvironment, the Cu₂O core catalyzes site-specific Fenton-like reactions to generate hydroxyl radicals (•OH), which activate TRPA1 channels on the cell membrane and thereby trigger a robust influx of extracellular Ca²⁺. Concurrently, the Dz component functions as a dual-mode biosensor-actuator: recognition of overexpressed miRNA-21 produces a fluorescent signal for real-time diagnosis monitoring, while cleavage of miRNA-25 alleviates suppression of the mitochondrial calcium uniporter (MCU), thereby promoting mitochondrial Ca²⁺ uptake. The synergistic coupling of a TRPA1-mediated cytosolic Ca²⁺ surge with MCU-driven mitochondrial import establishes a unidirectional Ca²⁺ gradient, culminating in irreversible mitochondrial Ca²⁺ overload and potent tumor cell apoptosis. This work not only demonstrates an efficiently spatiotemporal coordination of dual ion-interference pathways for precision targeting but also establishes a versatile framework for organelle specific modulation of pathological ion fluxes in precision oncology.