Scheme 1

Schematic illustration of antigen nanosponges (ANSs) as templates for biomineralization and cancer immunotherapy mechanisms. (A) Schematic representation of a dynamically continuous biomineralization strategy. Based on this strategy, we successfully constructed sub-100 nm biomineralized antigen nanosponges (BANSs) and large sizes of BANSs (LB). (B) After subcutaneous injection of small-sized and less negatively charged BANSs, it could be efficiently uptaken by immature APCs and generated drastic carbon dioxide (CO₂) in response to the acidic endo-/lysosomal environment for antigen cross-presentation to CD8⁺ T cells through the major histocompatibility complex class I (MHC I) pathway. The interaction of the T cell receptor (TCR) and the peptide-MHC-I complex on the tumor cell surface regulates CTLs response and tumor-killing ability. A combination of BANSs with anti-PD-1 antibody (αPD-1) generated synergistic effects that potentiated antitumor immunity