High brightness NIR-II nanofluorophores based on fused-ring acceptor molecules
nanofluorophores, fused-ring acceptor, propylenedioxy thiophene, high brightness, second near-infrared (NIR-II) biological imaging
It is challenging to develop molecular fluorophores in the second near-infrared (NIR-II) window with long wavelength emission and high brightness, which can improve the performance of biological imaging. Herein, we report a molecular engineering approach to afford NIR-II fluorophores with these merits based on fused-ring acceptor (FRA) molecules. Dioctyl 3,4-propylenedioxy thiophene (PDOT-C8) is utilized as the bridging donor to replace 3-ethylhexyloxy thiophene (3-EHOT), leading to more than 20 times enhancement of brightness. The nanofluorophores (NFs) based on the optimized CPTIC-4F molecule exhibit an emission peak of 1,110 nm with a fluorescence quantum yield (QY) of 0.39% (QY of IR-26 is 0.050% in dichloroethane as reference) and peak absorption coefficient of 14.5 × 104 M−1·cm−1 in aqueous solutions, which are significantly higher than those of 3-EHOT based COTIC-4F NFs. It is found that PDOT-C8 can weaken intermolecular aggregation, enhance protection of molecular backbone from water, and decrease backbone distortion, beneficial for the high brightness. Compared with indocyanine green with same injection dose, CPTIC-4F NFs show 10 times higher signal-to-background ratio for whole body vessels imaging at 1,300 nm long pass filters.
Tsinghua University Press
Xingfu Zhu,Chunchen Liu,Zhubin Hu,Haile Liu,Jiang Wang,Yang Wang,Xinyuan Wang,Rui Ma,Xiaodong Zhang,Haitao Sun,Yongye Liang, High brightness NIR-II nanofluorophores based on fused-ring acceptor molecules. NanoRes.2020, 13(9): 2570–2575