近红外二区荧光分子的设计与优化

DESIGN AND OPTIMIZATION OF NIR-II MOLECULAR FLUOREPHORES

朱兴富

11849254

硕士

材料工程

梁永晔

2020-05-30

2020-07-01

哈尔滨工业大学

深圳

近红外二区（NIR-II, 1000-1700 nm）荧光生物成像与常用的可见光（400-700nm）与近红外一区（NIR-I, 700-1000 nm）相比，具有组织穿透能力更深和信噪比更高等优势，近年来得到了广泛的关注。在 NIR-II 成像技术发展过程中，荧光染料扮演了重要的角色。分子染料具有优异的生物相容性，在临床转化中更具优势。然而，目前报道的分子染料荧光发射波长较短，而且难以同时具有较高的消光系数和高荧光量子产率（QY）。因此，开发高性能的 NIR-II 分子染料具有重要的意义。分子染料的结构与光学性能紧密相关，合理的分子结构设计可以有效提高染料的光学性能。基于此，本文针对具有屏蔽单元-给体-受体-给体-屏蔽单元（S-DA-D-S）结构及稠环受体分子结构的两类分子进行结构调控，并使用两亲性聚合物 DSPE-mPEG2000 对分子进行包裹得到水溶性纳米染料（NFs）。对于 S-D-AD-S 型分子，通过给体单元的优化，提高染料的 QY。对于稠环受体分子，通过对桥给体单元结构进行调控，使染料在水中的消光系数和 QY 都得到有效提高。本文具体内容如下：论文的第一部分对 NIR-II 成像的基本知识进行介绍。首先介绍了 NIR-II 成像的优势。然后简述了 NIR-II 生物成像技术的发展、NIR-II 染料的分类、NIR-II分子染料的研究进展。最后，基于对 NIR-II 分子染料的总结和分析，针对当前分子染料发展中的挑战，确定了本课题研究目的和内容。论文的第二部分介绍了实验材料与方法包括实验材料、实验仪器、分子染料的合成、NFs 的制备、粒径测试、吸收光谱测试、荧光光谱测试、光学稳定性及纳米粒子尺寸稳定性测试、生物成像、QY 计算方法、理论计算方法。论文的第三部分研究了具有不同给体单元的 S-D-A-D-S 型 NIR-II 分子染料结构与光学性能的关系。与分别用噻吩、3,4-乙烯二氧噻吩（EDOT）和 3,3-二丁基-3,4-丙烯二氧噻吩（PDOT-C4）作为给体单元的分子 n-FT、n-FE 和 n-FE346相比，用 3,4-乙烯二硫噻吩（EDST）作为给体单元的 n-FES 分子在甲苯中具有更高的 QY（5.45%）（以 IR-26 在二氯乙烷的 QY 为 0.05%作为参考）。用四个分子制备的 NFs 在水中的荧光发射峰均超过 1040 nm。用 n-FES 制备的纳米染料n-FES NFs 在水溶液中 QY 达到 1.25%，高于 n-FT NFs 的 0.01%，n-FE NFs 的0.27%和 n-FE346 NFs 的 0.89%。理论计算分析发现，基于 EDST 单元的 n-FES分子的共轭骨架扭曲较其他三个分子更大，减弱了纳米颗粒中染料分子间的聚集，降低荧光淬灭，使得 n-FES 相比于 n-FT、n-FE 和 n-FE346 在 NFs 中具有更高QY。论文的第四部分对稠环受体分子中桥给体单元的结构进行调控，提高了分子染料的光学性能。所制备的 NFs 的荧光发射峰位于 1110 nm，且具有较大的斯托克斯位移。与用 3-（2-乙基己基氧）噻吩（3-EHOT）和 3-（2-丁基辛基氧）噻吩（3-BOOT）作为桥给体的染料 COTIC-4F NFs 和 CBTIC-4F NFs 相比，3,3-二辛基-3,4-丙烯二氧噻吩（PDOT-C8）作为桥给体单元的染料 CPTIC-4F NFs 在磷酸缓冲盐溶液（PBS）中具有更优异的光学性能，吸收峰消光系数为 14.5 × 104 M-1cm-1，QY 为 0.39%。808 nm 激发的荧光亮度为 490，是目前在水溶液中亮度最高的 NIR-II 分子染料。理论计算与分子动态模拟研究发现，CPTIC-4F 分子骨架具有更强的疏水性保护及更小的扭曲，使得分子具有更高的荧光亮度。

Comparing with traditional visible (400-700 nm) and the first near-infrared (NIR-I, 700-1000 nm) regions, biological imaging in the second near-infrared region(NIR-II, 1000-1700 nm) has attracted a lot of attention due to its advantages of deeper tissue penetration and higher signal-to-noise ratio. The development of NIRII fluorophores plays an important role for the advance of NIR-II imaging. NIR-II molecular fluorophores are promising for clinical translation due to their good biocompatibility. However, the emission wavelength of the reported NIR-II molecular fluorophores needs to be further red-shifted and their absorption coefficients and fluorescence quantum yield (QY) should be simultaneously improved. Therefore, it is of great significance to explore NIR-II molecular fluorophores with required performance. The optical properties of molecular fluorophores are closely relevant to their structures and can be improved by rational molecule design. In this dissertation, NIRII molecular fluorophores with shielding unit-donor-acceptor-donor- shielding unit (S-D-A-D-S) structure and fused-ring acceptor (FRA) structure are developed by molecular engineering, and their nanofluorophores (NFs) were prepared by encapsulation with DSPE-mPEG2000 to enable aqueous solubility. For S-D-A-D-S molecules, their QYs were successfully improved by structural optimization of their donor units. For FRA molecules, simultaneously improved absorption coefficients and QYs were realized by structural optimization of their bridge donor units. The contents of this thesis are described as follows:In the first section, the fundamental information of NIR-II imaging is briefly introduced, including the advantages of NIR-II imaging and its development, the classification of NIR-II fluorophores and the development of molecular fluorophores. At the end, the aims and contents of this thesis are proposed.In the second section, experimental materials and methods are introduced, including experimental materials, experimental instruments, synthesis of molecular fluorophores, preparation of water-soluble NFs, the measurement of dynamic diameters of NFs, the measurement of absorption and emission spectra, the measurement of fluorophore stability, bio-imaging application, QY calculation and theoretical calculation methods.In the third section, donor engineering is applied on S-D-A-D-S fluorophores and the structure-optical property relationships are elucidated. Compared to n-FT with thiophene (T) as donor, n-FE with 3,4-ethylenedioxy thiophene (EDOT) as donor and n-FE346 with 3,3-dibutyl-3,4-propylenedioxy thiophene (PDOT-C4) as donor, the n-FES with 3,4-ethylenedithio thiophene (EDST) as donor shows the higher QY of 5.45% (Reference to IR-26 with QY of 0.05% in dichloroethane)in toluene. The fluorescence emission peaks of the four corresponding NFs are over 1040 nm in aqueous solutions. The QY of n-FES NFs is 1.25% in aqueous solutions, higher than 0.01% of n-FT NFs, 0.27% of n-FE NFs, and 0.89% of n-FE346 NFs. The theoretical calculation results show that the backbone of n-FES is more distorted than the other three molecules due to the bulkier EDST donor, which weakens intermolecular aggregation in NFs and reduces fluorescence quenching, resulting in higher QY of n-FES than n-FT, n-FE and n-FE346.In the fourth section, the bridge donor units are engineered to improve the optical properties of fused-ring acceptor molecules. The corresponding water-soluble NFs exhibited emission peaks located at 1110 nm and large Stokes shift. Compared to COTIC-4F NFs and CBTIC-4F NFs with 3-((2-ethylhexyl)oxy)thiophene (3- EHOT) and 3-((2-butyloctyl)oxy)thiophene (3-BOOT) as bridge donors, respectively, CPTIC-4F NFs with 3,3-dioctyl-3,4-propylenedioxy thiophene (PDOT-C8) as bridge donor exhibits better optical performance with peak extinction coefficient of 14.5 × 104 M-1 cm-1 , QY of 0.39% and the brightness of 490 (under 808 nm excitation) in phosphate buffer saline (PBS), which is ranked among the highest brightness values of the reported NIR-II molecular fluorophores. Theoretical calculation and molecular dynamic simulations demonstrate that the higher aqueous brightness of CPTIC-4F NFs can be attributed to the enhanced protection of molecular backbone from waterand decreased backbone distortion.

近红外二区成像 分子染料 结构调控 S-D-A-D-S 型分子 稠环受体分子

NIR-II imaging molecular fluorophores structure engineering S-D-AD-S molecules fused-ring acceptor molecules

中文

联合培养

南方科技大学

朱兴富. 近红外二区荧光分子的设计与优化[D]. 深圳. 哈尔滨工业大学,2020.