Abdollahi Sedigheh, Raissi Heidar, Farzad Farzaneh
Department of chemistry, University of Birjand, Birjand, Iran.
Sci Rep. 2025 Jul 24;15(1):27007. doi: 10.1038/s41598-025-12799-6.
Microplastics (MPs) and nanoplastics (NPs) have emerged as major environmental pollutants due to their persistence, widespread distribution, and ability to interact with organic contaminants, including antibiotics. This study employs molecular dynamics (MD) simulations to investigate the adsorption mechanisms of three commonly used antibiotics-ciprofloxacin, amoxicillin, and tetracycline-on two types of non-biodegradable microplastics: polypropylene (PP) and polystyrene (PS). Furthermore, the impact of microplastic aging, simulated by introducing oxidized and hydrophilic functional groups, on adsorption efficiency and interaction mechanisms has been explored. The total interaction energy of ciprofloxacin on polystyrene increased from - 121.57 kJ/mol (pristine) to -242.04 kJ/mol (aged), while the number of adsorbed molecules doubled from 5 to 10. Similarly, amoxicillin adsorption on aged polypropylene increased from 4 to 6 molecules, with total adsorption energy increasing from - 52.14 kJ/mol to -93.43 kJ/mol. Polystyrene microplastics demonstrated stronger adsorption than polypropylene, particularly for aromatic antibiotics like ciprofloxacin, where π-π interactions dominate. The Root Mean Square Deviation (RMSD), Radial Distribution Function (RDF), and Mean Squared Displacement (MSD) analyses further confirm the stability and persistence of these interactions. Additionally, the hydrogen bond analysis highlights the role of microplastic aging in facilitating stronger antibiotic binding. These findings suggest that aged microplastics act as potent carriers of antibiotics, potentially prolonging their environmental persistence and influencing microbial resistance patterns. The results reveal that, aged microplastics exhibit significantly higher antibiotic adsorption due to increased surface roughness and enhanced electrostatic interactions. By providing molecular-level insights into MP-antibiotic interactions, this study contributes to the broader understanding of emerging pollutants.
微塑料（MPs）和纳米塑料（NPs）因其持久性、广泛分布以及与包括抗生素在内的有机污染物相互作用的能力，已成为主要的环境污染物。本研究采用分子动力学（MD）模拟，研究三种常用抗生素——环丙沙星、阿莫西林和四环素——在两种不可生物降解的微塑料：聚丙烯（PP）和聚苯乙烯（PS）上的吸附机制。此外，还探讨了通过引入氧化和亲水官能团模拟的微塑料老化对吸附效率和相互作用机制的影响。环丙沙星在聚苯乙烯上的总相互作用能从-121.57 kJ/mol（原始状态）增加到-242.04 kJ/mol（老化状态），而吸附分子的数量从5个增加到10个，翻倍。同样，阿莫西林在老化聚丙烯上的吸附从4个分子增加到6个分子，总吸附能从-52.14 kJ/mol增加到-93.43 kJ/mol。聚苯乙烯微塑料表现出比聚丙烯更强的吸附能力，特别是对于像环丙沙星这样的芳香族抗生素，其中π-π相互作用占主导。均方根偏差（RMSD）、径向分布函数（RDF）和均方位移（MSD）分析进一步证实了这些相互作用的稳定性和持久性。此外，氢键分析突出了微塑料老化在促进更强抗生素结合方面的作用。这些发现表明，老化微塑料是抗生素的有效载体，可能延长其在环境中的持久性并影响微生物耐药模式。结果表明，老化微塑料由于表面粗糙度增加和静电相互作用增强，表现出显著更高的抗生素吸附能力。通过提供关于微塑料-抗生素相互作用的分子水平见解，本研究有助于更广泛地理解新兴污染物。
