Planar-structured thiadiazoloquinoxaline-based NIR-II dye for tumor phototheranostics

• Published in: Journal of materials chemistry. B, Materials for biology and medicine Materials for biology and medicine, 2024-05, Vol.12 (17), p.4197-427
• Main Authors: Zheng, Liangyu, Zhao, Ziqi, Xue, Chun, An, Lei, Na, Weidan, Gao, Fan, Shao, Jinjun, Ou, Changjin
• Format: Article
• Language: English
• Subjects: Absorption; Biocompatibility; Brightness; Chemical compounds; Dyes; Emission; Emissions; Fluorescence; Fluorophores; Infrared imaging; Medical imaging; Nanoparticles; Navigation; Near infrared radiation; Neoplasms; Phototherapy; Photothermal conversion; Steric hindrance; Tumors; Wavelength; Wavelengths
• ISSN: 2050-750X; 2050-7518
• DOI: 10.1039/d4tb00302k

Second near-infrared (NIR-II) fluorescence imaging shows huge application prospects in clinical disease diagnosis and surgical navigation, while it is still a big challenge to exploit high performance NIR-II dyes with long-wavelength absorption and high fluorescence quantum yield. Herein, based on planar π-conjugated donor-acceptor-donor systems, three NIR-II dyes (TP-DBBT, TP-TQ1, and TP-TQ2) were synthesized with bulk steric hindrance, and the influence of acceptor engineering on absorption/emission wavelengths, fluorescence efficiency and photothermal properties was systematically investigated. Compared with TP-DBBT and TP-TQ2, the TP-TQ1 based on 6,7-diphenyl-[1,2,5]thiadiazoloquinoxaline can well balance absorption/emission wavelengths, NIR-II fluorescence brightness and photothermal effects. And the TP-TQ1 nanoparticles (NPs) possess high absorption ability at a peak absorption of 877 nm, with a high relative quantum yield of 0.69% for large steric hindrance hampering the close π-π stacking interactions. Furthermore, the TP-TQ1 NPs show a desirable photothermal conversion efficiency of 48% and good compatibility. In vivo experiments demonstrate that the TP-TQ1 NPs can serve as a versatile theranostic agent for NIR-II fluorescence/photoacoustic imaging-guided tumor phototherapy. The molecular planarization strategy provides an approach for designing efficient NIR-II fluorophores with extending absorption/emission wavelength, high fluorescence brightness, and outstanding phototheranostic performance. The 6,7-diphenyl-[1,2,5]thiadiazoloquinoxaline-based NIR-II dye TP-TQ1 nanoparticles with a planar molecular conformation display a maximum absorption peak at 877 nm with a quantum yield of 0.69% and a photothermal conversion efficiency of 48%.