荧光DOM在激发三重态诱导β受体阻滞剂光解中的作用

The presence of dissolved organic matter (DOM) in natural waters has an important influence on photodegradation of pharmaceutical and personal care products (PPCPs). The important degradation pathway of PPCPs is the photooxidation induced by the excited triplet state of DOM(3DOM*). The photosensitive ability of 3DOM* is related with the source and composition of DOM. However, the direct contribution components of DOM for this ability are unclear. Taking cardiovascular drugs-beta blockers as the research object, this project intends to conduct research on the role of DOM fluorescent components (Fluorescent DOM) in photodegradation of beta-blockers induced by excited triplet state. .In this research, DOM will be fractionated to different components by cross-flow ultrafiltration and polarity separation method, then be identified by excitation–emission matrix (EEM) fluorescence spectroscopy, and those DOM with strong fluorescence will be selected as Fluorescent DOM（FDOM）. The optical, electrochemical, and photochemical properties of FDOM will be characterized to forecast the photosensitive ability. The photooxidation kinetics and pathways of beta-blockers in the presence of FDOM will be identified and quantified by steady-state photolysis experiments combined with probe quenching method. With the help of excited triplet sensitizer and model FDOM, the research will establish kinetic model, and reveal the photosensitive ability of FDOM components such as amino acids, quinones and phenols. The energy transfer and electron transfer mechanism also will be studied in the photodegradation process..The research results will contribute to get a clear understanding of photosensitive components of DOM for its excited triplet state photosensitive ability, and has important significance for understanding the environmental fate of beta blockers in natural waters.

自然水体中，溶解性有机质（DOM）对医药品及个人护理用品（PPCPs）的光解具有重要影响。激发三重态DOM（3DOM*）对PPCPs的光氧化是这类污染物降解的重要途径。3DOM*光敏能力与其来源和化学组成有关，但DOM中起直接贡献的组分还不清楚。本项目拟以心血管类药物β受体阻滞剂为研究对象，研究DOM中荧光组分（荧光DOM）对激发三重态诱导β受体阻滞剂光解的影响及机理。.通过切向超滤法和极性分离法并结合三维荧光光谱鉴定，从DOM中分离出荧光特性强的组分作为荧光DOM(FDOM)，分析FDOM的光学、光化学和电化学特性，鉴定FDOM中氨基酸、酚、醌荧光；通过稳态光解实验和探针猝灭方法，研究FDOM存在下β受体阻滞剂的光解动力学和光解路径；借助激发三重态光敏剂和模型FDOM荧光组分，建立动力学模型定量描述FDOM的光敏作用，揭示FDOM组分氨基酸、醌、酚的光敏贡献，阐明能量转移和电子转移机制。

激发三重态DOM（3DOM*）对PPCPs的光氧化是这类污染物降解的重要途径。3DOM*光敏能力与其来源和化学组成有关，但DOM中起直接贡献的组分还不清楚。本项目以心血管类药物β受体阻滞剂为研究对象，研究DOM中荧光组分（FDOM）对激发三重态诱导β受体阻滞剂光解的影响及机理。研究结果表明：①不同来源、不同分子量DOM的荧光特性差异明显，不仅表现在荧光峰种类的差异，还表现在荧光峰相对浓度的差异。猪粪和污泥DOM含蛋白质荧光峰明显，土壤DOM和FA含腐殖类荧光峰明显。大分子量DOM的蛋白类荧光峰强度强于小分子量DOM，而腐殖质峰荧光强度则表现相反。②DOM对药物光解的影响存在促进或抑制的双重作用，与光源条件、药物直接光解能力强弱、DOM荧光特性相关。在模拟日光条件下、药物直接光解能力弱、FDOM丰富尤其是蛋白类荧光物质丰富时，DOM表现为明显的促进作用。在模拟紫外光条件下、药物直接光解能力强、FDOM含量少时，DOM表现为明显的抑制作用。③ FA与无机离子共存时，两者的光敏作用存在交互作用，跟无机离子与FA中的腐殖质荧光峰的络合程度有关。④不同类型的FDOM产生自由基的能力差异明显。大分子量DOM和蛋白类FDOM产生3DOM*自由基的能力高于腐殖类FDOM，而猝灭药物与3DOM*反应能力则相反。异源FA猝灭自由基能力要强于本源FA。研究结果显示DOM中的荧光组分特性决定了其产生和猝灭3DOM*的能力，进一步影响了其对β受体阻滞剂的光敏作用。通过鉴定DOM中的FDOM特性，即可预测β受体阻滞剂在DOM存在下的自然水体中的环境归趋。