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An Ester-Substituted Semiconducting Polymer with Efficient Nonradiative Decay Enhances NIR-II Photoacoustic Performance for Monitoring of Tumor Growth |
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| Authors: | Menglei Zha Dr. Xiangwei Lin Prof. Jen-Shyang Ni Yaxi Li Yachao Zhang Xun Zhang Prof. Lidai Wang Prof. Kai Li |
| Affiliation: | 1. Department of Biomedical Engineering, Southern University of Science and Technology (SUSTech), Shenzhen, 518055 China These authors contributed equally to this work.;2. Department of Biomedical Engineering, City University of Hong Kong, 83 Tat Chee Ave, Kowloon, Hong Kong SAR City University of Hong Kong Shenzhen Research Institute, No. 8 Yuexing 1st RD, South Area, Hi-tech Park, Nanshan, Shenzhen, 518057 China These authors contributed equally to this work.;3. Department of Chemical and Materials Engineering, Photo-sensitive Material Advanced Research and Technology Center (Photo-SMART), National Kaohsiung University of Science and Technology, Kaohsiung, 80778 Taiwan;4. Department of Biomedical Engineering, Southern University of Science and Technology (SUSTech), Shenzhen, 518055 China;5. Department of Biomedical Engineering, City University of Hong Kong, 83 Tat Chee Ave, Kowloon, Hong Kong SAR |
| Abstract: | Photoacoustic agents have been of vital importance for improving the imaging contrast and reliability against self-interference from endogenous substances. Herein, we synthesized a series of thiadiazoloquinoxaline (TQ)-based semiconducting polymers (SPs) with a broad absorption covering from NIR-I to NIR-II regions. Among them, the excited s-BDT-TQE, a repeating unit of SPs, shows a large dihedral angle and narrow adiabatic energy as well as low radiative decay, attributing to its strongly electron-deficient ester-substituted TQ-segment. In addition, its more vigorous molecular motions trigger a higher reorganization energy that further yields an efficient photoinduced nonradiative decay, which has been carefully examined and understood by theoretical calculation. Thus, BDT-TQE SP-cored nanoparticles with twisted intramolecular charge transfer (TICT) feature exhibit a high NIR-II photothermal conversion efficiency (61.6 %) and preferable PA tracking of in situ hepatic tumor growth for more than 20 days. This study highlights a unique strategy for constructing efficient NIR-II photoacoustic agents via TICT-enhanced PNRD effect, advancing their applications for in vivo bioimaging. |
| Keywords: | photoacoustic photothermal conversion reorganization energy reversed AIE TICT |