Self-Luminous Probe with One-Step Energy Conversion from Bioluminescence to NIR-IIb

Area of Science:

• Materials Science
• Biomedical Imaging
• Nanotechnology

Background:

• Near-infrared (NIR) probes are crucial for deep-tissue imaging due to reduced light scattering and autofluorescence.
• Existing NIR probes often suffer from limited emission wavelengths and require complex multistep energy transfer processes.
• The development of efficient visible-light-to-NIR conversion is essential for advancing deep-penetration imaging capabilities.

Purpose of the Study:

• To establish direct wavelength conversion from visible light to the NIR-IIb region (>1500 nm).
• To develop novel sensitizer-activator ion pairs within host nanocrystals for efficient photon conversion.
• To create a self-luminous probe capable of converting bioluminescence to NIR-IIb luminescence for deep-seated lesion detection.

Main Methods:

• Designed and synthesized novel nanocrystals incorporating sensitizer-activator ion pairs with tailored energy levels.
• Utilized ZnS passivation via coherent epitaxial growth to enhance nanocrystal stability and quantum yield.
• Coupled the developed nanocrystals with luciferase to achieve one-step bioluminescence-to-NIR-IIb energy transfer.

Main Results:

• Prepared broadband visible-light-responsive nanocrystals exhibiting intense NIR-IIb emission.
• Achieved enhanced quantum yield (up to 7.4%) and stability through ZnS passivation.
• Demonstrated a maximum tissue penetration depth of 6 mm in a porcine model using the self-luminous probe.

Conclusions:

• The developed nanocrystal system enables efficient, one-step conversion of visible light and bioluminescence to NIR-IIb emission.
• The probe's superior photon-conversion performance and deep-penetration capability offer significant potential for high-resolution imaging of deep lesions.
• This work presents a promising strategy for advancing biomedical imaging by overcoming limitations of current NIR probes.