Modular Construction of AIE-Active Supramolecular Cages with Tunable Fluorescence for NIR-II Blood Vessel Imaging

Fluorescent supramolecular cages have attracted significant scientific interest owing to their widespread applications in molecular sensing, luminescent materials, and biological systems. However, the modular construction of such assemblies with tunable emission behaviors affording high-performance bioimaging applications is still challenging. Herein, we developed a general and straightforward protocol to formulate supramolecular cages with an aggregation-induced emission (AIE) tendency by using "donor–acceptor–donor (D–A–D)" adducts as building blocks. A series of box-shaped cages MA–MG with adjustable fluorescence from red to the second near-infrared (NIR-II) region were successfully prepared. In particular, the emission maximum of MG was located at 981 nm, behaving like the rare NIR-II emissive supramolecular cages thus far, and the cage-loaded nanoparticles MGNPs featured a high absolute quantum yield in the NIR-II region, which enabled them to perform well in blood vessel imaging.