Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstr. 4 6, 53115, Bonn, Germany.
Department of Colloid Chemistry, Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476, Potsdam, Germany.
Sci Rep. 2024 Oct 28;14(1):25853. doi: 10.1038/s41598-024-75785-4.
Micro- and nanoplastics can interact with various biologically active compounds forming aggregates of which the effects have yet to be understood. To this end, it is vital to characterize these aggregates of key compounds and micro- and nanoplastics. In this study, we examined the adsorption of the antibiotic tetracycline on four different nanoplastics, made of polyethylene (PE), polypropylene (PP), polystyrene (PS), and nylon 6,6 (N66) through chemical computation. Two separate approaches were employed to generate relevant conformations of the tetracycline-plastic complexes. In the first approach, we folded the plastic particle from individual polymer chains in the presence of the drug through multiple separate simulated annealing setups. In the second, more biased, approach, the neat plastic was pre-folded through simulated annealing, and the drug was placed at its surface in multiple orientations. The former approach was clearly superior to the other, obtaining lower energy conformations even with the antibiotic buried inside the plastic particle. Quantum chemical calculations on the structures revealed that the adsorption energies show a trend of decreasing affinity to the drug in the order of N66> PS> PP> PE. In vitro experiments on tetracycline-sensitive cell lines demonstrated that, in qualitative agreement with the calculations, the biological activity of tetracycline drops significantly in the presence of PS particles. Preliminary molecular dynamics simulations on two selected aggregates with each plastic served as first stability test of the aggregates under influence of temperature and in water. We found that all the selected cases persisted in water indicating that the aggregates may be stable also in more realistic environments. In summary, our data show that the interaction of micro- and nanoplastics with drugs can alter drug absorption, facilitate drug transport to new locations, and increase local antibiotic concentrations, potentially attenuating antibiotic effect and at the same time promoting antibiotic resistance.
微塑料和纳米塑料可以与各种具有生物活性的化合物相互作用，形成聚集体，其影响尚待理解。为此，对这些关键化合物和微塑料和纳米塑料的聚集体进行特征描述至关重要。在这项研究中，我们通过化学计算研究了抗生素四环素在四种不同的纳米塑料（由聚乙烯（PE）、聚丙烯（PP）、聚苯乙烯（PS）和尼龙 6,6（N66）制成）上的吸附作用。我们采用了两种不同的方法来生成四环素-塑料复合物的相关构象。在第一种方法中，我们通过多次单独的模拟退火设置，在药物存在的情况下从单个聚合物链折叠塑料颗粒。在第二种方法中，我们通过模拟退火预先折叠纯净的塑料，并在其表面以多种取向放置药物。前一种方法明显优于另一种方法，即使抗生素被埋在塑料颗粒内部，它也能获得更低能量的构象。对结构的量子化学计算表明，吸附能呈现出随药物亲和力降低的趋势，顺序为 N66>PS>PP>PE。体外实验表明，在四环素敏感细胞系中，与计算结果定性一致，四环素的生物活性在 PS 颗粒存在下显著下降。对两种选定的塑料与每种塑料的两个选定聚集体进行初步分子动力学模拟，作为聚集体在温度和水中影响下的第一个稳定性测试。我们发现所有选定的情况都在水中持续存在，这表明聚集体在更现实的环境中也可能稳定。总之，我们的数据表明，微塑料和纳米塑料与药物的相互作用可以改变药物的吸收，促进药物向新的位置运输，并增加局部抗生素浓度，从而潜在地减弱抗生素的作用，同时促进抗生素耐药性。
