吲哚菁绿 (ICG) 荧光依赖于具有平面和扭曲结构的单体并受到 H 聚集的抑制,International Journal of Molecular Sciences

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吲哚菁绿 (ICG) 荧光依赖于具有平面和扭曲结构的单体并受到 H 聚集的抑制
International Journal of Molecular Sciences ( IF 4.9 ) Pub Date : 2023-08-22 , DOI: 10.3390/ijms241713030
Bonghwan Chon ₁ , William Ghann ₂ , Jamal Uddin ₂ , Bahman Anvari _{3,

4} , Vikas Kundra _{1,

5}

Affiliation

吲哚菁绿 (ICG) 作为近红外 (NIR) 荧光染料的光学性质取决于溶剂介质的性质和染料浓度。在水的ICG吸收光谱中，在高浓度下，在700 nm处有吸收最大值，这意味着H聚集体。ICG 稀释后，主吸收峰位于 780 nm，表明是单体。然而，在乙醇中，最大吸收为780 nm，并且无论ICG浓度如何，吸收光谱的形状都是相同的，表明乙醇中的ICG仅以单体形式存在，没有H-聚集体。我们发现发射是由于单体形式造成的，并且随着 H-聚集体的形成而减少。在荧光光谱中，820 nm 发射带在低浓度下占主导地位，而在高浓度下，我们发现发射峰转换为 880 nm，这表明通过 ICG 的扭曲分子内电荷转移 (TICT) 过程形成了一种新形式。在 NIR-I 和 -II 区域中，ICG 在乙醇中的 NIR 荧光强度分别比在水中亮约 12 倍和 9 倍。我们提出了 ICG 的能量图来描述通过 ICG 结构（例如单体、H 聚集和 TICT 单体形式）的吸收和发射跃迁。

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Indocyanine Green (ICG) Fluorescence Is Dependent on Monomer with Planar and Twisted Structures and Inhibited by H-Aggregation

The optical properties of indocyanine green (ICG) as a near-infrared (NIR) fluorescence dye depend on the nature of the solvent medium and the dye concentration. In the ICG absorption spectra of water, at high concentrations, there were absorption maxima at 700 nm, implying H-aggregates. With ICG dilution, the main absorption peak was at 780 nm, implying monomers. However, in ethanol, the absorption maximum was 780 nm, and the shapes of the absorption spectra were identical regardless of the ICG concentration, indicating that ICG in ethanol exists only as a monomer without H-aggregates. We found that emission was due to the monomer form and decreased with H-aggregate formation. In the fluorescence spectra, the 820 nm emission band was dominant at low concentrations, whereas at high concentrations, we found that the emission peaks were converted to 880 nm, suggesting a new form via the twisted intramolecular charge transfer (TICT) process of ICG. The NIR fluorescence intensity of ICG in ethanol was approximately 12- and 9-times brighter than in water in the NIR-I and -II regions, respectively. We propose an energy diagram of ICG to describe absorptive and emissive transitions through the ICG structures such as the monomer, H-aggregated, and TICT monomer forms.

更新日期：2023-08-23

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