Abstract: | Sensing nonradiation‐induced singlet oxygen (1O2) in whole‐animal is deemed as one of the most challenging tasks in noninvasive techniques due to the µs level lifetime of 1O2 and quenching by numerous reductants in tissues. Here a distinct chemiluminescent (CL) nanosensor (NTPE‐PH) that boasts ultrahigh concentrated CL units in one nanoparticle is reported. Taking advantage of the intramolecular energy transfer mechanism that promises high energy transfer efficiency and the aggregation‐induced emission behavior that guarantees high CL amplification, the NTPE‐PH sensor is sensitive to a nm level 1O2. Experiments demonstrate that the NTPE‐PH yields a highly selective CL response toward 1O2 among common reactive oxygen species. With proved low cytotoxicity and good animal compatibility, real‐time mapping of ultratrace 1O2 in whole‐animal during acute and chronic inflammations is first achieved. It is anticipated that the NTPE‐PH sensor can be a useful tool for monitoring 1O2 variation during immune response and pathological processes corresponding to different stimuli, even with drug treatment included. |