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.