Alkyl Chain Engineering for High-Brightness Near-Infrared-II Aggregation-Induced Emission Nanoprobes toward...

Area of Science:

• Biomedical Engineering
• Materials Science
• Optical Imaging

Background:

• Second near-infrared (NIR-II) fluorescence imaging (1000-1700 nm) offers deep-tissue penetration for in vivo bioimaging.
• Aggregation-induced emission (AIE) luminogens are promising for NIR-II probes but often lack sufficient brightness.
• Existing probes face limitations due to molecular constraints and environmental quenching, hindering practical applications.

Purpose of the Study:

• To develop a high-brightness NIR-II AIE nanoprobe for improved in vivo bioimaging.
• To enhance the brightness and performance of AIE-based NIR-II probes through molecular design.
• To demonstrate the utility of the developed probe for vasculature imaging and tumor detection.

Main Methods:

• Designed and synthesized a novel NIR-II AIE nanoprobe (TT12,8-B NPs) by increasing molecular alkyl lengths.
• Optimized the nanoprobe to enhance aggregate hydrophobicity and intermolecular packing, boosting molar absorptivity and quantum yield (QY).
• Evaluated the nanoprobe's brightness, photostability, biocompatibility, and performance in vivo using fluorescence angiography in animal models.

Main Results:

• The optimized TT12,8-B NPs demonstrated nearly 4-fold higher brightness compared to existing high-QY NIR-II AIE probes.
• Achieved high-clarity multiscale vasculature imaging with a signal-to-background ratio >10 and a resolution of 49 μm.
• Successfully enabled early tumor detection and differentiation between nascent and established tumors.

Conclusions:

• The developed TT12,8-B NPs represent a significant advancement in NIR-II AIE nanoprobe brightness and performance.
• The molecular design strategy of increasing alkyl lengths offers a viable approach to enhance AIE probe characteristics.
• The probe's capabilities in angiography and tumor detection highlight its potential for clinical translation in biomedical imaging.