The environmental fate and toxicity of microplastic particles are dominated by their surface properties. In the environment, an adsorbed layer of biomolecules and natural organic matter forms the so-called eco-corona. A quantitative description of how this eco-corona changes the particles’ colloidal interactions is still missing. Here, we demonstrate with colloidal probe-atomic force microscopy that eco-corona formation on microplastic particles introduces a compressible film on the surface, which changes the mechanical behavior. We measure single particle–particle interactions and find a pronounced increase of long-range repulsive interactions upon eco-corona formation. These force-separation characteristics follow the Alexander–de Gennes (AdG) polymer brush model under certain conditions. We further compare the obtained fitting parameters to known systems like polyelectrolyte multilayers and propose these as model systems for the eco-corona. Our results show that concepts of fundamental polymer physics, like the AdG model, also help in understanding more complex systems like biomolecules adsorbed to surfaces, i.e., the eco-corona.

中文翻译：

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生态电晕覆盖的微塑料颗粒的排斥相互作用定量遵循聚合物刷的建模

微塑料颗粒的环境归宿和毒性主要取决于它们的表面特性。在环境中，生物分子和天然有机物的吸附层形成了所谓的生态电晕。这种生态电晕如何改变粒子的胶体相互作用的定量描述仍然缺失。在这里，我们用胶体探针原子力显微镜证明，微塑料颗粒上的生态电晕形成在表面引入了可压缩的薄膜，从而改变了机械行为。我们测量了单个粒子-粒子的相互作用，发现在生态电晕形成时长程排斥相互作用显着增加。这些力分离特性在某些条件下遵循 Alexander-de Gennes (AdG) 聚合物刷模型。我们进一步将获得的拟合参数与聚电解质多层等已知系统进行比较，并将其作为生态电晕的模型系统。我们的研究结果表明，基础聚合物物理学的概念，如 AdG 模型，也有助于理解更复杂的系统，如吸附到表面的生物分子，即生态电晕。