Unlocking the NIR-II AIEgen for High Brightness through Intramolecular Electrostatic Locking.

Angew Chem Int Ed Engl

Department of Chemistry, Hong Kong Branch of Chinese National Engineering Research Center for Tissue Restoration and Reconstruction, Division of Life Science, and State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Kowloon, Hong Kong, 999077, China.

Published: July 2024

AI Article Synopsis

  • Fluorescent imaging in the NIR-II window offers a promising method for non-invasive clinical diagnosis, but developing bright fluorophores has been challenging.
  • A new strategy utilizing intramolecular electrostatic locking in TSEH fluorophores, achieved by integrating sulfur into the thiophene bridge, significantly enhances fluorescent brightness in both solution and aggregated states.
  • TSEH nanoparticles demonstrate great potential for vascular and tumor imaging due to a high signal-to-background ratio and are effective in antigen detection, outperforming traditional fluorophores in low-concentration scenarios.

Article Abstract

Fluorescent imaging and biosensing in the near-infrared-II (NIR-II) window holds great promise for non-invasive, radiation-free, and rapid-response clinical diagnosis. However, it's still challenging to develop bright NIR-II fluorophores. In this study, we report a new strategy to enhance the brightness of NIR-II aggregation-induced emission (AIE) fluorophores through intramolecular electrostatic locking. By introducing sulfur atoms into the side chains of the thiophene bridge in TSEH molecule, the molecular motion of the conjugated backbone can be locked through intramolecular interactions between the sulfur and nitrogen atoms. This leads to enhanced NIR-II fluorescent emission of TSEH in both solution and aggregation states. Notably, the encapsulated nanoparticles (NPs) of TSEH show enhanced brightness, which is 2.6-fold higher than TEH NPs with alkyl side chains. The in vivo experiments reveal the feasibility of TSEH NPs in vascular and tumor imaging with a high signal-to-background ratio and precise resection for tiny tumors. In addition, polystyrene nanospheres encapsulated with TSEH are utilized for antigen detection in lateral flow assays, showing a signal-to-noise ratio 1.9-fold higher than the TEH counterpart in detecting low-concentration antigens. This work highlights the potential for developing bright NIR-II fluorophores through intramolecular electrostatic locking and their potential applications in clinical diagnosis and biomedical research.

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Source
http://dx.doi.org/10.1002/anie.202404142DOI Listing

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