Penetrate-Then-Gate Bioorthogonal In Situ Cancer Vaccination for Aligned Antigen Capture and Localized TLR7/8...

In situ cancer vaccination is limited when antigens diffuse or degrade, adjuvants act systemically, and the timing of immune licensing is misaligned. Here, we report a penetrate-then-gate design that decouples distribution from activation. Complementary, clickable poly(propylene sulfide) (PPS) nanoparticles (∼25 nm) first penetrated the tumor parenchyma after intravenous administration. Brief near-infrared irradiation then gated intracellular ROS generation by a photosensitizer (PPa), oxidizing PPS to poly(propylene sulfone) (PPSU), exposing azide/DBCO handles, and driving in situ assembly. The resulting PPSU network captured endogenous antigens, thereby colocalizing antigen availability with TLR7/8 agonist (IMDQ). In mice, optical imaging indicated earlier and sustained intratumorally exposure at irradiation for coadministration (the two formulations premixed before injection) versus sequential dosing (PPa-PPS_N3 first, followed by IMDQ-PPS_DBCO before irradiation), aligning exposure with the licensing window. Across multiple cancer models, coadministration improved primary control, elicited rechallenge protection, and suppressed distant growth, with restrained systemic cytokines. This work applies a spatiotemporal alignment principle for in situ vaccination to achieve precise and durable tumor immunotherapy in a modular way.