TADF-based NIR-II semiconducting polymer dots for in vivo 3D bone imaging

Area of Science:

• Biomedical Engineering
• Materials Science
• Optical Imaging

Background:

• Second near-infrared (NIR-II) fluorescence imaging is revolutionizing image-guided surgery.
• Conventional NIR dyes have limitations including shallow penetration and high false positive rates.
• Development of novel NIR-II probes is crucial for advancing surgical visualization.

Purpose of the Study:

• To design and synthesize novel NIR-II emissive semiconducting polymer dots (Pdots) incorporating thermally activated delayed fluorescence (TADF) moieties.
• To investigate the impact of TADF units on Pdot optical properties and molecular packing.
• To evaluate the potential of these Pdots for in vivo 3D bone imaging.

Main Methods:

• Synthesis of NIR-II emissive semiconducting polymer dots (Pdots) with TADF moieties.
• Characterization of Pdot optical properties, including emission maxima (1064-1100 nm) and fluorescence quantum yields (0.40-1.58%).
• Density-functional theory (DFT) calculations to understand TADF mechanism and molecular packing.
• In vivo 3D bone imaging in mice using the developed Pdots.

Main Results:

• Developed Pdots exhibit emission in the 1064-1100 nm range with fluorescence quantum yields up to 1.58%.
• DFT calculations elucidated the role of TADF units in Pdot optical properties.
• Successful demonstration of in vivo 3D bone imaging in mice, showcasing deep tissue penetration and clear visualization.

Conclusions:

• Novel TADF-incorporated Pdots offer superior NIR-II fluorescence properties compared to conventional dyes.
• These Pdots are effective for in vivo 3D bone imaging, with potential for diagnosing bone-related diseases.
• This study provides a framework for designing advanced NIR-II Pdots for biomedical applications.