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

• Published in: Chemical science (Cambridge) 2022-08, Vol.13 (34), p.174-181
• Main Authors: Hsu, Keng-Fang, Su, Shih-Po, Lu, Hsiu-Feng, Liu, Ming-Ho, Chang, Yuan Jay, Lee, Yi-Jang, Chiang, Huihua Kenny, Hsu, Chao-Ping, Lu, Chin-Wei, Chan, Yang-Hsiang
• Format: Article
• ISSN: 2041-6520; 2041-6539
• DOI: 10.1039/d2sc03271f

Intraoperative fluorescence imaging in the second near-infrared (NIR-II) region heralds a new era in image-guided surgery since the success in the first-in-human liver-tumor surgery guided by NIR-II fluorescence. Limited by the conventional small organic NIR dyes such as FDA-approved indocyanine green with suboptimal NIR-II fluorescence and non-targeting ability, the resulting shallow penetration depth and high false positive diagnostic values have been challenging. Described here is the design of NIR-II emissive semiconducting polymer dots (Pdots) incorporated with thermally activated delayed fluorescence (TADF) moieties to exhibit emission maxima of 1064-1100 nm and fluorescence quantum yields of 0.40-1.58% in aqueous solutions. To further understand how the TADF units affect the molecular packing and the resulting optical properties of Pdots, in-depth and thorough density-functional theory calculations were carried out to better understand the underlying mechanisms. We then applied these Pdots for in vivo 3D bone imaging in mice. This work provides a direction for future designs of NIR-II Pdots and holds promising applications for bone-related diseases. A series of NIR-II fluorescent TADF-incorporated polymer dots were successfully synthesized. The function of the TADF moiety was fully studied and the bio-applications of these polymer dots including bone imaging were also demonstrated.