J‐Aggregation Strategy toward Potentiated NIR‐II Fluorescence Bioimaging of Molecular Fluorophores

Abstract

AbstractMolecular fluorophores emitting in the second near‐infrared (NIR‐II, 1000–1700 nm) window with strong optical harvesting and high quantum yields hold great potential for in vivo deep‐tissue bioimaging and high‐resolution biosensing. Recently, J‐aggregates are harnessed to engineer long‐wavelength NIR‐II emitters and show unique superiority in tumor detection, vessel mapping, surgical navigation, and phototheranostics due to their bathochromic‐shifted optical bands in the required slip‐stacked arrangement aggregation state. However, despite the preliminary progress of NIR‐II J‐aggregates and theoretical study of structure‐property relationships, further paradigms of NIR‐II J‐aggregates remain scarce due to the lack of study on aggregated fluorophores with slip‐stacked fashion. In this effort, how to utilize the specific molecular structure to form slip‐stacked packing motifs with J‐type aggregated exciton coupling is emphatically elucidated. First, several molecular regulating strategies to achieve NIR‐II J‐aggregates containing intermolecular interactions and external conditions are positively summarized and deeply analyzed. Then, the recent reports on J‐aggregates for NIR‐II bioimaging and theranostics are systematically summarized to provide a clear reference and direction for promoting the development of NIR‐II organic fluorophores. Eventually, the prospective efforts on ameliorating and promoting NIR‐II J‐aggregates to further clinical practices are outlined.