Molecular engineering of AIE luminogens for NIR-II/IIb bioimaging and surgical navigation of lymph nodes

Sentinel lymph node (SLN) imaging is vital for tumor staging and treatment decision-making, and current methods for SLN imaging suffer from a short retention time, poor penetration depth, and low signal-to-noise ratio. As a cutting-edge technology, second near-infrared wavelength region (NIR-II) aggregation-induced emission (AIE) luminogens (AIEgens) are promising for circumventing these challenges; however, construction of such molecules with ultralong absorption wavelengths remains a significant challenge. Here we conducted molecular engineering, constructing a NIR-II AIEgen (NIR-920) with the longest maximum absorption wavelength. NIR-920 nanoparticles (NPs) presented bright fluorescence and achieved high-performance imaging of lymph nodes in the NIR-II/NIR-IIb window. Compared with the clinically used indocyanine green (ICG), NIR-920 nanoparticles have many superior advantages, including retention time, penetration depth, signal-to-noise ratio, and photostability. Utilization of NIR-920 NPs allowed fast and accurate surgical navigation of SLNs. This work provides useful insight into designing extraordinarily prominent molecular probes for high-quality lymph node imaging and surgical navigation.