Achieving Near‐Infrared Organic Room‐Temperature Phosphorescence for High‐Resolution Immune Response Monitoring and Bioimaging

Organic near-infrared (NIR) room-temperature phosphorescent (RTP) materials hold great potential for bioimaging due to their ability to eliminate background noise and tissue autofluorescence. Here, we synthesized octa-ring fused RTP molecules (TPP-BN and TPP-BF) with B─N coordination bonds via a two-step reaction, enabling NIR phosphorescent emission at 819 nm and a 28.6 ms lifetime. Using PMMA-b-PEG as host and surfactant to stabilize the RTP molecules, we fabricated PMMA-b-PEG based nanoparticles (PNPs) with five-fold brighter afterglow than conventional F127-based methods (FNPs). We further developed a granzyme B (GrB)-responsive nanoprobe (Q-BFNP) that achieves specific and quantitative detection. In vivo studies demonstrated their ability to monitor and distinguish tumor immune response with the signal-to-background ratio (SBR) as high as 216.4. This study provides a new method for constructing NIR organic RTP probes and advances applications of RTP materials in real-time, high-contrast bioimaging and tumor immune monitoring.