Dragonfly-shaped near-infrared AIEgen with optimal fluorescence brightness for precise image-guided cancer surgery

Organic near-infrared (NIR) emitters with simultaneously high absorption coefficient and photoluminescence quantum yield (PLQY) are highly desirable for biomedical imaging yet seldom reported because these two aspects are usually contradictory. The conjugated planar structures exhibit strong absorption but the emission is seriously quenched in aggregate state, whereas the twisted unplanar molecules display opposite phenomena. Herein, we report a kind of dragonfly-shaped NIR aggregation-induced emission luminogen (AIEgen) with both high absorption coefficient (6.24 × 10⁴ M^-1 cm^-1) and superior PLQY (51.2%) for precise image-guided cancer surgery. The compound possessing a conjugated structure with vibrational substitutes has been synthesized, in which the good conjugation enables strong absorption, and the molecular vibration affords AIE signature. Moreover, the nonfluorescent processes are significantly suppressed, making every effort to boost fluorescence. The highly bright and stable AIE nanoparticles warrant efficient in vitro cellular imaging and in vivo tumor imaging. Moreover, the fluorescence imaging-guided cancer surgery helps to precisely delineate tiny tumor nodules, significantly improving the cancer surgery outcome. This work will inspire more insights into the development of organic NIR emitters with high brightness for biomedical applications.