Thienothiadiazole-Based NIR-II Dyes with D-A-D Structure for NIR-II Fluorescence Imaging Systems

Area of Science:

• Organic Chemistry
• Biomedical Imaging
• Materials Science

Background:

• Fluorescence imaging (FI) in the second near-infrared optical window (NIR-II, 1000-1700 nm) offers high resolution, real-time imaging, and deep tissue penetration.
• Donor-Acceptor-Donor (D-A-D) organic small molecules are attractive for their tunable structures and efficient renal clearance.
• Development of novel fluorescent cores for NIR-II FI remains a challenge, with existing cores often based on benzobisthiadiazole (BBTD) or TTQ.

Purpose of the Study:

• To design and synthesize novel D-A-D type NIR-II fluorescent dyes utilizing a new TTDT acceptor core.
• To develop corresponding nanoparticles for enhanced stability and imaging performance.
• To evaluate the in vivo performance of these novel dyes for fluorescence imaging applications.

Main Methods:

• Synthesis of two D-A-D NIR-II dyes (TTDT-TF and TTDT-TSF) using Stille coupling reactions.
• Preparation of corresponding nanoparticles from the synthesized dyes.
• Evaluation of photostability, fluorescence signals, and in vivo imaging performance, including signal-to-background ratio (SBR).

Main Results:

• Successful synthesis of two novel D-A-D NIR-II dyes based on the TTDT acceptor.
• TTDT-TF-based nanoparticles demonstrated superior photostability and strong NIR-II fluorescence signals.
• In vivo experiments showed significant accumulation of TTDT-TF NPs at tumor sites with a high SBR.

Conclusions:

• The developed TTDT-based D-A-D fluorophores show significant potential for advanced NIR-II fluorescence imaging.
• These novel dyes offer improved imaging quality for applications such as image-guided surgery and therapy.
• The TTDT core represents a promising platform for the development of next-generation NIR-II imaging agents.