Theoretical and Experimental Studies on the Near-Infrared Photoreaction Mechanism of a Silicon Phthalocyanine Photoimmunotherapy Dye: Photoinduced Hydrolysis by Radical Anion Generation
Theoretical and Experimental Studies on the Near-Infrared Photoreaction Mechanism of a Silicon Phthalocyanine Photoimmunotherapy Dye: Photoinduced Hydrolysis by Radical Anion Generation
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DOI：
10.1002/cplu.202000338
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发表时间：
2020-05-25
期刊：
影响因子：
3.4
通讯作者：
Taketsugu, Tetsuya
中科院分区：
文献类型：
--
作者：
Kobayashi, Masato;Harada, Mei;Taketsugu, Tetsuya
IR700是一种用于近红外(NIR)光免疫治疗的硅酞菁染料，其释放的配体在近红外吸收后启动癌细胞死亡，尽管其光化学机制尚不清楚。这一理论研究表明，即使在激发态，即>；1.30 eV，由于高的离解能，近红外光也很难激活硅配体的直接离解。相反，辐射产生IR700自由基阴离子，导致与附近的水分子发生酸碱反应(即计算出自由基阴离子的pK(B)为7.7)，从而产生疏水配体释放的染料。这提出了两种可能性：(1)水分子参与了配体的释放；(2)光不是硅配体解离所必需的，因为形成IR700自由基阴离子就足够了。实验证据证实了(1)以O-18标记的水为溶剂的可能性，而(2)是由配体交换的pH依赖性所支持的，从而完整地描述了硅配体的解离机理。
Ligand release from IR700, a silicon phthalocyanine dye used in near-infrared (NIR) photoimmunotherapy, initiates cancer cell death after NIR absorption, although its photochemical mechanism has remained unclear. This theoretical study reveals that the direct Si-ligand dissociation by NIR light is difficult to activate because of the high dissociation energy even in excited states, i. e., >1.30 eV. Instead, irradiation generates the IR700 radical anion, leading to acid-base reactions with nearby water molecules (i. e., calculated pK(b) for the radical anion is 7.7) to produce hydrophobic ligand-released dyes. This suggests two possibilities: (1) water molecules participate in ligand release and (2) light is not required for Si-ligand dissociation as formation of the IR700 radical anion is sufficient. Experimental evidence confirmed possibility (1) by using O-18-labeled water as the solvent, while (2) is supported by the pH dependence of ligand exchange, providing a complete description of the Si-ligand bond dissociation mechanism.