Inorganic Biomaterials as Immunomodulators: Dual Strategies for Activation and Suppression
Precise regulation of the immune system is essential for maintaining physiological homeostasis and treating disease. Insufficient immune activation leads to tumor development, whereas excessive immune responses cause autoimmune diseases or chronic inflammation. Inorganic biomaterials, owing to their unique intrinsic properties such as enzyme-mimicking catalytic functions, tunable composition and morphology, degradability, and inherent bioactivity, have transformed from conventional carriers into versatile platforms capable of actively regulating immune responses. This review summarizes recent progress in immunoregulatory inorganic biomaterials, highlighting their dual capacities to induce immune activation or immune suppression. For immune activation, inorganic materials serve as adjuvants to enhance antigen presentation, induce immunogenic cell death (ICD), and reprogram immune cell metabolism, enabling applications in tumor treatment. For immune suppression, specific inorganic materials effectively eliminate excessive reactive oxygen species (ROS), modulate the functions of inflammatory cells such as neutrophils, and promote the development of immunosuppressive cell populations, including regulatory T cells and M2 macrophages, thereby re-establishing immune tolerance in autoimmune diseases. Despite remaining challenges in mechanistic verification, long-term biosafety, and clinical translation, inorganic biomaterials offer a promising multifunctional platform for achieving precise immune interventions across cancer immunotherapy, tissue regeneration, and autoimmune disease management.