NIR-II fluorescence imaging without intended excitation light.

Area of Science:

• Biomedical Optics
• Medical Imaging
• Fluorescence Imaging

Background:

• Second near-infrared window (NIR-II) imaging typically uses laser diodes for excitation.
• Lack of suitable optical probes has hindered white light-excited NIR-II imaging.
• Existing methods like indocyanine green (ICG) suffer significant photo-quenching under laser irradiation.

Purpose of the Study:

• To develop and evaluate multi-wavelength white light-emitting diode (LED) excited NIR-II imaging.
• To introduce a novel blue-shifted NIR-II dye, TPA-TQT, for white light excitation.
• To assess the performance of this system for biomedical imaging and image-guided surgery.

Main Methods:

• Utilized a novel blue-shifted NIR-II dye (TPA-TQT) with multi-wavelength white LEDs.
• Compared white LED excitation with single-wavelength LED and traditional laser excitation.
• Evaluated imaging resolution for blood vessels and lymphatic capillaries.
• Assessed the system's efficacy in monitoring hindlimb ischemia-reperfusion and lymphatic inflammation models.
• Performed white LED-excited NIR-II fluorescence imaging-guided surgery (FIGS) in tumor-bearing mice.

Main Results:

• The white LED system showed minimal photo-quenching compared to 808 nm laser irradiation.
• Multi-wavelength LED excitation provided lower background noise than single-wavelength LED.
• High image resolution was achieved, identifying blood vessels (103 μm) and lymphatic capillaries (129.8 μm).
• The system successfully monitored physiological processes like ischemia-reperfusion and lymphatic inflammation.
• White LED-excited NIR-II FIGS clearly delineated small metastatic tumor lesions (∼350 μm) and guided surgical removal.

Conclusions:

• Multi-wavelength white LED-based NIR-II imaging is a viable alternative to laser excitation.
• This novel system offers improved dye stability and imaging performance.
• The technology demonstrates significant potential for precise tumor delineation and image-guided surgery.
• White LED-excited NIR-II imaging holds promise for various biomedical applications.