Airborne nanoplastics can be inhaled to threaten human health, but research on the inhaled nanoplastic toxicity is in its infancy, and interaction mechanisms are largely unknown. By means of molecular dynamics simulation, we employed spherical nanoplastics of different materials and aging properties to predict and elucidate nanoplastic transformations in alveolar fluid and impacts on the lung surfactant (LS) film at the alveolar air-water interface. Results showed spontaneous adsorption of LS molecules on nanoplastics of 10 nm in diameter, and the adsorption layer can be defined as coronas, which increased the particle size, reduced and equalized the surface hydrophobicity, and endowed nanoplastics with negative surface charges. Nanoplastics of polypropylene and polyvinylchloride materials were dissolved by LS, which could increase bioavailability of polymers and toxic additives. Aging properties represented by the nanoplastic size, polymer’s molecular weight and surface chemistry altered nanoplastic transformations through modulating competition between polymer-LS and polymer-polymer interactions. Upon transferred to the alveolar air-water interface through vesicle fusion, nanoplastics could interfere with the normal biophysical function of LS through disrupting the LS ultrastructure and fluidity, and prompting collapse of the LS film. These results provide new molecular level insights into fate and toxicity of airborne nanoplastics in human respiratory system.

吸入空气中的纳米塑料会威胁人类健康，但对吸入纳米塑料毒性的研究还处于起步阶段，相互作用机制在很大程度上是未知的。通过分子动力学模拟，我们采用不同材料和老化特性的球形纳米塑料来预测和阐明肺泡液中的纳米塑料转变以及对肺泡空气-水界面处的肺表面活性剂 (LS) 膜的影响。结果表明 LS 分子在 10 纳米塑料上的自发吸附 纳米塑料的直径，吸附层可以定义为电晕，它增加了粒径，降低和平衡了表面疏水性，并赋予了纳米塑料表面负电荷。LS溶解聚丙烯和聚氯乙烯材料的纳米塑料，可以增加聚合物和有毒添加剂的生物利用度。以纳米塑料尺寸、聚合物的分子量和表面化学为代表的老化特性通过调节聚合物-LS 和聚合物-聚合物相互作用之间的竞争来改变纳米塑料的转化。通过囊泡融合转移到肺泡气-水界面后，纳米塑料可以通过破坏 LS 超微结构和流动性并促使 LS 膜塌陷来干扰 LS 的正常生物物理功能。