Structural modulation of aggregation-induced emission luminogens for NIR-II fluorescence imaging/photoacoustic imaging of tumors.

Concurrent near-infrared-II (NIR-II) fluorescence imaging (FLI) and photoacoustic imaging (PAI) holds tremendous potential for effective disease diagnosis owing to their combined benefits and complementary features, in particular on the basis of a single molecule. However, the simultaneous guarantee of high-quality NIR-II FLI and PAI is recognized to be challenging impeded by the competitive photophysical processes at the molecular level. Herein, a simple organic fluorophore, namely T-NSD, is finely engineered with facile synthetic procedures through delicately modulating the rigidity and electron-withdrawing ability of the molecular acceptor. The notable advantages of fabricated T-NSD nanoparticles include a large Stokes shift, intense fluorescence emission in the NIR-II region, and anti-quenching properties in the aggregated states, which eventually enable the implementation of dual-modal NIR-II FLI/PAI in a 4T1 tumor-xenografted mouse model with reliable performance and good biocompatibility. Overall, these findings present a simple strategy for the construction of NIR-II optical agents to allow multimodal disease diagnosis.