Constructing J-aggregates of cyanine dye for NIR-II in vivo dynamic vascular imaging and long-term targeting of tumors.

Cyanine molecules with the second near-infrared (NIR-II) emission hold great potential for bioimaging owing to their great biocompatibility, but the scissor-like structure of these molecules poses a major bottleneck in obtaining efficient NIR-II fluorescence probes. Constructing J-aggregates represents a promising strategy for obtaining biomedical NIR-II emissive materials. However, achieving J-aggregates in cyanine dyes with large torsion angles between the heterocyclic rings poses a challenge. In this study, we introduced the guanidine of tumor molecular targeted peptide 1 (TMTP1) to increase steric hindrance of IR-783 and reduce the angle of IR-783 scissors. The near-coplanar structure of IR-783@peptide TMTP1 composite facilitates the formation of a novel J-aggregates (IR-783-LP-TMTP1) with super-stable effect for NIR-II in vivo dynamic vascular imaging and remarkable tumor targeting capability. The stable emission wavelength and high spatial resolution of J-aggregates was demonstrated for brain and ear vasculature bioimaging under 808 nm laser excitation. Additionally, J-aggregates exhibits robust tumor-targeting capability towards cervical tumors, indicating their potential in cervical cancer diagnosis. This work develops a molecular design strategy to construct bright NIR-II J-aggregates with super-stable and robust tumor-targeting properties and paving the way for improving bioimaging performance of similar molecules.