Rational design of topology-defined DNA nanoframeworks for antigen delivery and cross-presentation.

DNA nanoframeworks (DNFs) provide structurally programmable platforms for antigen delivery, yet how framework topology influences antigen cross-presentation remains unclear. Here, we systematically compare DNFs with distinct geometries and mechanical properties and demonstrate that rigid frameworks exhibit enhanced serum stability and antigen delivery efficiency. Notably, antigen encapsulation within DNFs consistently promotes cross-presentation compared with surface display, despite similar or lower cellular uptake. This behavior is consistent with an encapsulation-protection mechanism that preserves antigen integrity during intracellular processing. While DNF-mediated dendritic cell activation can be readily attained, the efficiency of antigen cross-presentation is primarily determined by antigen availability, which is in turn regulated by framework topology and antigen localization. This establishes antigen delivery as the key bottleneck for subsequent CD8⁺ T cell activation. Collectively, these two factors are identified as key design parameters for optimizing DNA-based antigen delivery systems.