Department of Chemistry, Renmin University of China , 100872 Beijing, People's Republic of China.
Langmuir. 2017 Jun 13;33(23):5938-5946. doi: 10.1021/acs.langmuir.7b01065. Epub 2017 May 30.
Polydopamine (PDA) generally demonstrates as an efficient free-radical scavenger. However, its free-radical chemistry under illumination is unclear, which becomes important in view of growing studies of polydopamine applications in photoprotector and photothermal therapy. In this study, for the first time, we reported an experimental investigation of the generation of hydroxyl free radicals from ultraviolet (UV)-illuminated polydopamine in an aqueous environment. By using terephthalic acid as fluorescent probe, we measured hydroxyl radicals generated from UV-illuminated polydopamine with different shapes and sizes. The morphology of PDA shows significant influence on its productions of hydroxyl free radicals. Through characterizations of UV-vis absorption spectroscopy, fluorescence spectroscopy, X-ray photoelectron spectrometry, mass spectrometry, and thermogravimetric analysis, we demonstrated the change of PDA nanomaterials brought by UV-light illumination in composition and thermal stability. We proposed a tentative mechanism for interpreting the relationship between morphology and photostability of PDA nanomaterials. These results reveal underlying complexity of polydopamine chemistry under light illumination that will deepen our understanding and benefit its further application.
聚多巴胺（PDA）通常表现为一种有效的自由基清除剂。然而，其在光照下的自由基化学性质尚不清楚，鉴于聚多巴胺在光保护剂和光热治疗中的应用研究不断增多，这一点变得尤为重要。在这项研究中，我们首次报道了在水相环境中，用紫外线（UV）照射聚多巴胺产生羟基自由基的实验研究。通过使用对苯二甲酸作为荧光探针，我们测量了不同形状和大小的 UV 照射聚多巴胺产生的羟基自由基。PDA 的形态对其产生羟基自由基有显著影响。通过紫外可见吸收光谱、荧光光谱、X 射线光电子能谱、质谱和热重分析等手段，我们证明了 UV 光照射下 PDA 纳米材料在组成和热稳定性方面的变化。我们提出了一种解释 PDA 纳米材料形态和光稳定性之间关系的推测机制。这些结果揭示了光照射下聚多巴胺化学的内在复杂性，将加深我们的理解并有助于其进一步应用。
