Packing-accelerated consecutive NIR excitation (PACE) enables high energy photocatalysis and antitumor immunity in vivo.

A mechanism called packing-accelerated consecutive excitation (PACE) lets low-energy near-infrared photons drive high-energy single electron transfer reactions, using a self-assembling ruthenium complex Ru-3 that forms nanoaggregates with an excited-state absorption band near 1315 nm and nanosecond triplet lifetimes. Under dual 808 nm/1310 nm irradiation, Ru-3 nanoparticles oxidize mitochondrial NADH to NAD+, triggering cGAS-STING-dependent pyroptosis and shifting tumor-associated macrophages to an M1 phenotype. In multiple murine tumor models this photocatalysis drives tumor regression with minimal systemic toxicity.