NIR-II silver chalcogenide nanocrystals: synthesis, photophysical modulation and deep-tissue fluorescence imaging

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Imaging

Background:

• Silver chalcogenide nanocrystals (Ag₂X NCs; X = S, Se, Te) are emerging as low-toxicity fluorescent probes for the second near-infrared window (NIR-II, 1000-1700 nm).
• Advances in synthesis, emission tuning, and surface modification have enhanced their brightness, stability, and biocompatibility for biological applications.

Purpose of the Study:

• To provide a comprehensive review of silver chalcogenide nanocrystal development for NIR-II fluorescence.
• To highlight strategies for enhancing NIR-II fluorescence and their applications in deep-tissue bioimaging.
• To examine current challenges and future research directions for biomedical translation.

Main Methods:

• Review of synthetic methodologies for Ag₂X NCs.
• Analysis of strategies for improving NIR-II fluorescence.
• Compilation of applications in various deep-tissue bioimaging scenarios.
• Critical evaluation of challenges and future research avenues.

Main Results:

• Ag₂X NCs demonstrate significant potential as NIR-II emitters due to improved properties.
• Expanding applications include vascular/lymphatic mapping, organ/skeletal visualization, and targeted/activatable imaging.
• Emerging multiplexed and multimodal imaging approaches are being developed.

Conclusions:

• Continued research is needed to clarify emission mechanisms and develop scalable, eco-friendly synthesis.
• Optimizing surface chemistry is crucial for reliable biological interactions and enhanced imaging accuracy.
• Further investigation into long-term biosafety is essential for clinical translation of Ag₂X NCs as next-generation NIR-II probes.