Liu Chunchen, Ma Huilong, Hu Zhubin, Tian Rui, Ma Rui, Xu Yifan, Wang Xinyuan, Zhu Xingfu, Yu Panpan, Zhu Shoujun, Sun Haitao, Liang Yongye
Department of Materials Science and Engineering, Shenzhen Key Laboratory of Printed Organic Electronics, Southern University of Science and Technology, Shenzhen, China.
State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai, China.
Front Chem. 2021 Sep 2;9:739802. doi: 10.3389/fchem.2021.739802. eCollection 2021.
Molecular fluorophores emitting in the second near-infrared (NIR-II) window with good renal excretion ability are favorable for bio-imaging and clinical applications. So far, renally excretable fluorophores are still less studied. Understanding the influences of molecular structure on optical properties and renal excretion abilities are vital for fluorophore optimization. Herein, a series of shielding unit-donor-acceptor-donor-shielding unit (S-D-A-D-S) NIR-II molecular fluorophores are designed and synthesized with dialkoxy chains substituted benzene as the S unit. The anchoring positions of dialkoxy chains on benzene are tuned as meso-2,6, para-2,5, or ortho-3,4 to afford three fluorophores: BGM6P, BGP6P and BGO6P, respectively. Experimental and calculation results reveal that alkoxy side chains anchored closer to the conjugated backbone can provide better protection from water molecules and PEG chains, affording higher fluorescence quantum yield (QY) in aqueous solutions. Further, these side chains can enable good encapsulation of backbone, resulting in decreased binding with albumin and improved renal excretion. Thus, fluorophore BGM6P with meso-2,6-dialkoxy chains exhibits the highest quantum yield and fastest renal excretion. This work emphasizes the important roles of side chain patterns on optimizing NIR-II fluorophores with high brightness and renal excretion ability.
在第二近红外（NIR-II）窗口发射且具有良好肾脏排泄能力的分子荧光团有利于生物成像和临床应用。到目前为止，可经肾脏排泄的荧光团仍较少被研究。了解分子结构对光学性质和肾脏排泄能力的影响对于荧光团的优化至关重要。在此，设计并合成了一系列以二烷氧基链取代苯为屏蔽单元的屏蔽单元-供体-受体-供体-屏蔽单元（S-D-A-D-S）近红外二区分子荧光团。将二烷氧基链在苯环上的锚定位置调整为间位-2,6、对位-2,5或邻位-3,4，分别得到三种荧光团：BGM6P、BGP6P和BGO6P。实验和计算结果表明，锚定在共轭主链附近的烷氧基侧链能够更好地保护免受水分子和聚乙二醇链的影响，在水溶液中提供更高的荧光量子产率（QY）。此外，这些侧链能够使主链得到良好的包裹，减少与白蛋白的结合并改善肾脏排泄。因此，具有间位-2,6-二烷氧基链的荧光团BGM6P表现出最高的量子产率和最快的肾脏排泄速度。这项工作强调了侧链模式在优化具有高亮度和肾脏排泄能力的近红外二区荧光团方面的重要作用。
