Department of Chemistry, Jagiellonian University, ul. Ingardena 3, 30-060, Kraków, Poland.
J. Heyrovský Institute of Physical Chemistry, Academy of Sciences of the Czech Republic, v.v.i. Dolejškova 3, 18223, Prague 8, Czech Republic.
Chemistry. 2017 Apr 19;23(22):5307-5316. doi: 10.1002/chem.201605945. Epub 2017 Mar 30.
By reducing the surface tension of the air-water interface in alveoli, lung surfactant (LS) is crucial for proper functioning of the lungs. It also forms the first barrier against inhaled pathogens. In this study we inspect the interactions of LS models with a dangerous air pollutant, benzo[a]pyrene (BaP). Dipalmitoylphosphatidylcholine (DPPC), 1-palmitoyl-2-oleoylphosphatidylcholine, and their 1:1 mixture are used as LS models. Pressure-area isotherms are employed to study macroscopic properties of the monolayers. We find that addition of BaP has a condensing effect, manifested by lowering the values of surface pressure and shifting the isotherms to smaller areas. Atomistic details of this process are examined by means of molecular dynamics simulations. We show that initially BaP molecules are accumulated in the monolayers. Upon compression, they are forced to the headgroups region and eventually expelled to the subphase. BaP presence results in reduction of monolayer hydration in the hydrophilic region. In the hydrophobic region it induces increased chain ordering, reduction of monolayer fluidity, and advances transition to the liquid condensed phase in the DPPC system.
通过降低肺泡中气-水界面的表面张力，肺表面活性剂（LS）对于肺的正常功能至关重要。它还构成了抵御吸入病原体的第一道屏障。在这项研究中，我们检查了 LS 模型与一种危险空气污染物苯并[a]芘（BaP）的相互作用。二棕榈酰磷脂酰胆碱（DPPC）、1-棕榈酰基-2-油酰基磷脂酰胆碱及其 1:1 混合物被用作 LS 模型。使用压力-面积等温线来研究单层的宏观性质。我们发现 BaP 的添加具有冷凝作用，表现为表面压力值降低和等温线向较小面积移动。通过分子动力学模拟研究了这个过程的原子细节。我们表明，最初 BaP 分子在单层中积累。在压缩过程中，它们被迫进入头部区域，最终被挤出到亚相。BaP 的存在导致亲水区单层水合作用减少，而在疏水区则诱导链有序增加、单层流动性降低，并促进 DPPC 体系向液体冷凝相转变。
