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bioRxiv · 10.1101/2020.05.30.125104

Protein enhanced NIR-IIb emission of indocyanine green for functional imaging

He, M.·Wu, D.·Zhang, Y.·Fan, X.·Lin, H.·Qian, J.
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Abstract

Fluorescence imaging performed in the 1500-1700 nm spectral range (labeled as near-infrared IIb, NIR-IIb) promises high imaging contrast and spatial resolution for its little photon scattering effect and minimum auto-fluorescence. Though inorganic and organic probes have been developed for NIR-IIb bioimaging, most are in preclinical stage, hampering further clinical application. Herein, we showed that indocyanine green (ICG), an US Food and Drug Administration (FDA)-approved agent, exhibited remarkable amount of NIR-IIb emission when dissolved into different protein solutions, including human serum albumin, rat bile, and fetal bovine serum. We performed fluorescence imaging in NIR-IIb window to visualize structures of lymph system, extrahepatic biliary tract and cerebrovascular. Results demonstrated that proteins promoted NIR-IIb emission of ICG in vivo and that NIR-IIb imaging with ICG preserved higher signal-to-background ratio (SBR) and spatial resolution compared with the conventional near-infrared II (NIR-II) fluorescence imaging. Our findings confirm that NIR-IIb fluorescence imaging can be successfully performed using the clinically approved agent ICG. Further clinical application in NIR-IIb region would hopefully be carried out with appropriate ICG-protein solutions.

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He, M., Wu, D., Zhang, Y., Fan, X., Lin, H., Qian, J.. 2020-05-31. Protein enhanced NIR-IIb emission of indocyanine green for functional imaging. https://doi.org/10.1101/2020.05.30.125104

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