Microplastics (MPs) have been recognized as a global concern due to their potential health effect, as MPs could adsorb and carry various pollutants in aquatic environment. In the present study, a new environmental behavior related to polyvinyl chloride microplastics (PVC-MPs) and the underlying mechanism were described. Our results showed that the photo-aged PVC-MPs could affect the transformation of cephalosporin antibiotics. For instance, the presence of altered PVC-MPs significantly accelerated the hydrolysis of cefazolin (CFZ), but exhibited negligible effect on the degradation of cephalexin (CFX). As indicated by in situ Fourier transform infrared spectra and theoretical calculations, hydrogen bonds could be formed between β-lactam carbonyl of CFZ and the oxygen-containing moieties on the aged PVC-MP surfaces. The hydrogen-bonding was able to significantly increase the positive atomic Mulliken charge on the β-lactam carbonyl carbon, thus narrowing the energy gap of CFZ hydrolysis and subsequently enhancing the disruption of β-lactam ring. While for CFX, instead of the β-lactam carbonyl, the amide amino group was involved in the hydrogen-bonding due to the structural difference. Therefore, in addition to increasing the adsorption capacity, the aged PVC-MPs could act as the catalyst to mediate the transformation of antibiotics. Our study would help improve the understanding for interactions between contaminants and MPs in natural environments.

微塑料 (MPs) 因其潜在的健康影响而被认为是全球关注的问题，因为 MPs 可以吸附和携带水生环境中的各种污染物。在本研究中，描述了与聚氯乙烯微塑料 (PVC-MPs) 相关的新环境行为及其潜在机制。我们的结果表明，光老化的 PVC-MPs 会影响头孢菌素类抗生素的转化。例如，改变的 PVC-MP 的存在显着加速了头孢唑啉 (CFZ) 的水解，但对头孢氨苄 (CFX) 的降解的影响可以忽略不计。原位傅里叶变换红外光谱和理论计算表明，CFZ的β-内酰胺羰基与老化的PVC-MP表面的含氧部分之间可以形成氢键。氢键能够显着增加β-内酰胺羰基碳上的正原子Mulliken电荷，从而缩小CFZ水解的能隙并随后增强β-内酰胺环的破坏。而对于 CFX，由于结构差异，酰胺氨基代替 β-内酰胺羰基参与氢键。因此，除了增加吸附能力外，老化的 PVC-MPs 还可以作为催化剂来介导抗生素的转化。我们的研究将有助于提高对自然环境中污染物和 MP 之间相互作用的理解。由于结构差异，酰胺氨基而不是 β-内酰胺羰基参与氢键。因此，除了增加吸附能力外，老化的 PVC-MPs 还可以作为催化剂来介导抗生素的转化。我们的研究将有助于提高对自然环境中污染物和 MP 之间相互作用的理解。由于结构差异，酰胺氨基而不是 β-内酰胺羰基参与氢键。因此，除了增加吸附能力外，老化的 PVC-MPs 还可以作为催化剂来介导抗生素的转化。我们的研究将有助于提高对自然环境中污染物和 MP 之间相互作用的理解。