A dual-enzyme-like nanozyme adjuvant alleviates tumor hypoxia to enhance photothermally ferroptosis-immune synergistic tumor therapy

Immune adjuvants play a critical role in cancer vaccines and emerging therapies. However, conventional adjuvants may fail to effectively stimulate cytotoxic T lymphocyte (CTL)-mediated immune responses. Nanozyme-based adjuvants, particularly manganese-based nanozymes, demonstrate significant potential by integrating enzymatic activity with immune modulation. Herein, we developed a dual-enzyme-like nanozyme adjuvant (Mn 3 O 4 &MLT@PDA-AS1411, MMPA) through the integration of Mn 3 O 4 nanozyme and melatonin (MLT) using polydopamine, which alleviates tumor hypoxia to enhance photothermally augmented ferroptosis-immune synergistic therapy. The ferroptosis is cooperatively enhanced by Mn 3 O 4 nanozyme-mediated reactive oxygen species generation and glutathione depletion, synergizing with MLT-induced HIF-1α suppression. Concurrently, HIF-1α inhibition and ferroptosis activation cooperate to suppress HSP70 expression, thereby amplifying the mild photothermal therapy and synergistically inducing immunogenic cell death. Furthermore, the degradation product of MMPA, Mn 2+ , activates the cGAS-STING pathway and promotes dendritic cell maturation and CTL infiltration. In vivo studies demonstrate that this strategy effectively alleviates tumor hypoxia, resulting in the complete suppression of distant tumors in a metastatic model. This approach also first explores the promotion of ferroptosis and immune activation of MLT, providing an innovative strategy for multi-mechanism synergistic treatment. • Nanozyme adjuvant for photothermally enhanced ferroptosis-immunotherapy. • Melatonin inhibits HIF-1α, enhancing ferroptosis and immunogenic cell death. • Mn 2+ activates cGAS-STING, promoting DC maturation and CTL infiltration.