Department of Physical Chemistry, Faculty of Pharmacy, University of Santiago de Compostela, Spain.
Faculty of Chemistry, Jagiellonian University, Ingardena 3, 30-060 Kraków, Poland.
Colloids Surf B Biointerfaces. 2017 Oct 1;158:634-642. doi: 10.1016/j.colsurfb.2017.07.016. Epub 2017 Jul 13.
The behaviour of Langmuir monolayers corresponding to unsaturated fatty acids belonging to the omega-9 (oleic acid), omega-3 (α-linolenic and stearidonic acids) and omega-6 (linoleic, γ-linolenic and eicosadienoic acids) series was studied in order to get insight into the influence of various factors (such as subphase temperature, length, degree of unsaturation and position of the double bonds in the aliphatic chains) on the molecular conformation of these fatty acids spread at the A/W interface. The obtained results derived from the surface pressure - area isotherms, compressibility modulus and monolayer thickness prove that the lift-off and the limiting areas of investigated films increase both with the number of double bonds and length of the hydrocarbon chain. Also, the monolayers are more compressible (more fluid) upon increasing their tails unsaturation degree. However, eicosadienoic (EA) film is more rigid due to its longer acyl chain. Polyunsaturated fatty acids (PUFAs) monolayers, except for EA, exhibit anomalous temperature dependence (area contraction with increasing temperature), which was attributed to the increased solubility of PUFAs molecules with temperature. The recorded thickness values of the monolayers were compared with those estimated from theoretical molecular conformations in order to establish the orientation and configuration of molecules in different surface states of their monolayer.
为了深入了解各种因素（如亚相温度、链长、不饱和度和脂链双键位置）对在 A/W 界面上展开的这些脂肪酸的分子构象的影响，研究了属于 omega-9（油酸）、omega-3（α-亚麻酸和 stearidonic 酸）和 omega-6（亚油酸、γ-亚麻酸和二十碳二烯酸）系列的不饱和脂肪酸的 Langmuir 单层的行为。从表面压-面积等温线、压缩模量和单层厚度获得的结果证明，所研究的薄膜的脱附和极限面积都随着双键数目和烃链长度的增加而增加。此外，随着尾部不饱和度的增加，单层变得更具可压缩性（更具流动性）。然而，由于其较长的酰链，二十碳二烯酸（EA）膜更硬。除了 EA 之外，多不饱和脂肪酸（PUFA）单层表现出异常的温度依赖性（随温度升高面积收缩），这归因于 PUFAs 分子随温度升高的溶解度增加。记录的单层厚度值与从理论分子构象估计的值进行了比较，以便确定在其单层的不同表面状态下分子的取向和构型。
