Yu Xiaoqin, Lang Mengfan, Huang Daofen, Yang Chengfang, Ouyang Zhuozhi, Guo Xuetao
College of Natural Resources and Environment, Northwest A&F University, Yangling, Shaanxi 712100, China.
School of Environmental Engineering, Xuzhou University of Technology, Xuzhou 221000, China.
Sci Total Environ. 2022 Feb 1;806(Pt 4):150954. doi: 10.1016/j.scitotenv.2021.150954. Epub 2021 Oct 15.
In recent years, microplastics (MPs) pollution, as a global environmental problem, has been widely concerned by countries all over the world. However, the research on the impact of MPs on human health is still limited. In this study, we studied the photo-transformation behavior of polystyrene microplastics (PS-MPs) under ultraviolet light and its toxicity to Caco-2 cells. Our results showed that the surface of PS-MPs was roughened by light, and cracks and pits appeared. UV-vis spectra showed that the opening of phenyl ring and the formation of carbonyl group might exist in this process. Based on FTIR and 2D-COS analysis, we observed the formation of carbonyl group and hydroxyl group, and preliminarily determined that the order of photo-transformation of PS-MPs was 698 (CH) > 752 (CH) > 1030 (CO) > 3645 (OH/OOH) > 1740 (CO). XPS showed that the photo-transformation of PS-MPs was a process in which carbon-containing functional groups were gradually partially transformed into oxygen-containing functional groups. Finally, the toxicity results showed that with the increase of PS-MPs concentration and the extension of light irradiation time, the survival rate of Caco-2 cells gradually decreased and the integrity of cell membrane was destroyed. The increased cytotoxicity can be explained at least in part by the fact that the toxicity of oxygen-containing functional groups is greater than that of carbon-containing functional groups, but how these functional groups affect the cytotoxicity of cells still needs sustained research in the future. This study can provide new insights for understanding the environmental behavior and ecological effects of PS-MPs in the environment.
近年来，微塑料（MPs）污染作为一个全球性环境问题，已受到世界各国广泛关注。然而，关于微塑料对人类健康影响的研究仍较为有限。在本研究中，我们研究了聚苯乙烯微塑料（PS-MPs）在紫外光下的光转化行为及其对Caco-2细胞的毒性。我们的结果表明，PS-MPs的表面因光照而变得粗糙，出现了裂缝和凹坑。紫外可见光谱表明，此过程中可能存在苯环的开环以及羰基的形成。基于傅里叶变换红外光谱（FTIR）和二维相关光谱（2D-COS）分析，我们观察到了羰基和羟基的形成，并初步确定PS-MPs的光转化顺序为698（CH）>752（CH）>1030（CO）>3645（OH/OOH）>1740（CO）。X射线光电子能谱（XPS）表明，PS-MPs的光转化是一个含碳官能团逐渐部分转化为含氧官能团的过程。最后，毒性结果表明，随着PS-MPs浓度的增加和光照时间的延长，Caco-2细胞的存活率逐渐降低，细胞膜完整性遭到破坏。细胞毒性增加至少部分可以用含氧官能团的毒性大于含碳官能团的毒性来解释，但这些官能团如何影响细胞的细胞毒性仍有待未来持续研究。本研究可为理解PS-MPs在环境中的环境行为和生态效应提供新的见解。
