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Updated: Sep 30, 2025
A Bright NIR-II Fluorescence Probe for Vascular and Tumor Imaging
Published on: March 17, 2023
Counterion-Paired Bright Heptamethine Fluorophores with NIR-II Excitation and Emission Enable Multiplexed Biomedical
Yang Yang1, Caixia Sun1, Shangfeng Wang1
1Department of Chemistry, State Key Laboratory of Molecular Engineering of Polymers, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials and iChem, Fudan University, Shanghai, 200433, China.
Abstract:
Photon excitation and emission at the NIR-II spectral window enable high-contrast deep-tissue bioimaging. However, multiplexed imaging with NIR-II excitation and emission has been hampered by the limited chemical strategies to develop bright fluorophores with tunable absorption in this spectral regime. Herein, we developed a series of heptamethine cyanines (HCs) with varied absorption/emission maxima spanning from 1100 to 1600 nm through a physical organic approach. A bulky counterion paired to HCs was found to elicit substantial improvements in absorptivity (7-fold), brightness (14-fold), and spectral profiles in water, addressing a notorious quenching problem of NIR-II cyanines due to aggregation and polarization. We demonstrated the utilities of HC1222 and HC1342 for high-contrast dual-color imaging of circulatory system, lymphatic structures, tumor, and organ function in living mice under 1120 nm and 1319 nm excitation, showing HCs as a promising platform for non-invasive bioimaging.
