The increasing risk of human exposure to emerging nanoparticles (NPs) has created a wide concern about their inhalation toxicity. Once NPs are inhaled, they get through the branching airway to deposit in the alveoli, where a thin pulmonary surfactant (PS) layer acts as the first barrier against them entering the deep lung. However, in terms of the inhalation toxicity of NPs, the mechanisms by which inhaled NPs interact with the PS layer and how the morphological change of NPs due to the PS layer interactions influences the subsequent fate of NPs are still elusive. By using molecular dynamics simulations, we investigate the interactions between graphene nanosheets (GNs) and the PS layer. It is found that when GNs suspend above or slowly penetrate the PS layer, PS molecules can spontaneously be extracted from the layer and made to form inverse micelles via cooperative molecular motion and rearrangement on the GN surfaces. We demonstrate that the PS layer tension and GN properties like size, oxidation ratio and curvature significantly affect the extraction dynamics. Notably, for curved GNs, only the concave surface can vigorously extract PS molecules, showing that the dispersive adhesion between GN and PS dominates the extracting and rearranging process. Our results propose new mechanisims for the experimental findings on the inhalation toxicity of graphene-family nanomaterials. Moreover, bearing in mind that the surface properties of GNs have been masked by adsorbed PS molecules, the newly formed structure may act like a corona that influences the biological identity of GNs. Therefore, anyone either evaluating inhalation toxicity or promoting biomedical applications of GNs should consider the first contact with PS at the air–water interface in alveoli.

中文翻译：

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提取肺表面活性剂以在悬浮的石墨烯纳米片上形成反胶束†

人类暴露于新兴纳米颗粒（NPs）的风险日益增加，引起了人们对其吸入毒性的广泛关注。吸入NP后，它们会通过分支气道沉积在肺泡中，在肺泡中，薄薄的肺表面活性剂（PS）层是阻止它们进入深肺的第一道屏障。然而，就NPs的吸入毒性而言，吸入NP与PS层相互作用的机理以及由于PS层相互作用而导致的NPs形态变化如何影响NP的后续命运仍不清楚。通过使用分子动力学模拟，我们研究了石墨烯纳米片（GNs）和PS层之间的相互作用。发现当GN悬在PS层上方或缓慢穿透PS层时，通过GN表面上的协同分子运动和重排。我们证明了PS层的张力和GN属性（如大小，氧化比和曲率）会显着影响萃取动力学。值得注意的是，对于弯曲的GN，只有凹面才能剧烈提取PS分子，这表明GN和PS之间的分散粘附主导了提取和重排过程。我们的结果为石墨烯家族纳米材料的吸入毒性的实验发现提出了新的机理。此外，请记住，GNs的表面特性已被吸附的PS分子掩盖，新形成的结构可能会像电晕一样起作用，从而影响GNs的生物学特性。所以，