Scheme 1.

MMP NDs with dual cGAS-STING activation for cancer metalloimmunotherapy. Metal cations and anions with the strongest cGAS-STING activation were screened using 293-Dual™ mSTING cells and then employed to construct bimetallic oxide MMO NDs, then MMP NDs were obtained by DSPE-PEG_5k modification. MMP NDs containing Mn²⁺ and MoO₄²⁻ showed effective cGAS-STING activation. After systemic administration, MMP NDs could consume the highly expressed GSH in tumor cells, break the redox balance, inhibit the activity of the GPX4 enzyme, and subsequently lead tumor cells ferroptosis. Tumor debris in the presence of MMP NDs would then trigger tumor-specific cell immunity.