In the second near-infrared spectral window (NIR-II; with wavelengths of 1,000–1,700 nm), in vivo fluorescence imaging can take advantage of reduced tissue autofluorescence and lower light absorption and scattering by tissue. Here, we report the development and in vivo application of a NIR-II phosphorescent probe that has lifetimes of hundreds of microseconds and a Stokes shift of 430 nm. The probe is made of glutathione-capped copper–indium–selenium nanotubes, and in acidic environments (pH 5.5–6.5) switches from displaying fluorescence to phosphorescence. In xenograft models of osteosarcoma and breast cancer, intravenous or intratumoral injections of the probe enabled phosphorescence imaging at signal-to-background ratios, spatial resolutions and sensitivities higher than NIR-II fluorescence imaging with polymer-stabilized copper–indium–sulfide nanorods. Phosphorescence imaging may offer superior imaging performance for a range of biomedical uses.
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This work was supported by the National Natural Science Foundation of China (51803161, 51533007 and 61622117), National Key Research and Development Program of China (2017YFA0205200), Office of Science Biological and Environmental Research Program, US Department of Energy (DE-SC0008397) and National Cancer Institute Centers of Cancer Nanotechnology Excellence grant CCNE-TR U54 CA119367.
The authors declare no competing interests.
Peer review information Nature Biomedical Engineering thanks Zhen Chao Dong and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer reviewer reports are available.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
Supplementary Methods, Discussion, Figs. 1–33, Tables 1–3, References and captions for Supplementary Videos 1–4.
In vivo video-rate NIR-II intensity imaging of a nude mouse bearing 143B tumours, in lateral position at 24 h post-injection of CISe nanotubes.
In vivo video-rate NIR-II intensity imaging of a nude mouse bearing 143B tumours, in supine position at 24 h post-injection of CISe nanotubes.
In vivo video-rate NIR-II intensity imaging of a nude mouse bearing 143B tumours, in lateral position at 24 h post-injection of PEG-CIS nanorods.
In vivo video-rate NIR-II intensity imaging of a nude mouse bearing 143B tumours, in supine position at 24 h post-injection of PEG-CIS nanorods.
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Chang, B., Li, D., Ren, Y. et al. A phosphorescent probe for in vivo imaging in the second near-infrared window. Nat Biomed Eng (2021). https://doi.org/10.1038/s41551-021-00773-2