Lipid bilayers are active participants in many crucial biological processes. They can be observed in different phases, liquid and solid, respectively. The liquid phase is predominant in biological systems. The solid phase, both crystalline and gel phases, is under investigation due to its resilience to mechanical stress and tight packing of lipids. The mechanical properties of lipids affect their dynamics, therefore influencing the transformation of cell plasma and the endomembrane. Mechanical properties of lipid bilayers are also an important parameter in the design and production of supramolecular lipid-based drug delivery systems. To this end, in this work, we focused on investigating the effect of solid phases of lipid bilayers on their structural parameters and mechanical properties using theoretical molecular dynamics studies on atomistic models of whole vesicles. Those include area per lipid, membrane thickness, density vesicle profiles, bending rigidity coefficient, and area compressibility. Additionally, the bending rigidity coefficient was measured using the flicker noise spectroscopy. The two approaches produced very similar and consistent results. We showed that, contrary to our expectations, bending rigidity coefficients of solid-ordered bilayers for vesicles decreased with an increase in lipid transition temperature. This tendency was reverse in planar systems. Additionally, we have observed an increase of membrane thickness and area compressibility and a decrease of area per lipid. We hope these results will provide valuable mechanical insight for the behavior in solid phases and differences between spherical and planar confirmations.

中文翻译：

---

DMPC，DPPC，DSPC和HSPC固体有序双层的力学性能测定。

脂质双层是许多关键生物学过程的积极参与者。可以分别在液相和固相的不同相中观察到它们。液相在生物系统中占主导地位。固相，包括结晶相和凝胶相，由于其对机械应力的回弹性和脂质的紧密堆积而正在研究中。脂质的机械性质影响其动力学，因此影响细胞血浆和内膜的转化。脂质双层的机械性质也是基于超分子脂质的药物递送系统的设计和生产中的重要参数。为此，在这项工作中，我们专注于研究脂质双层的固相对其结构参数和力学性能的影响，使用了基于整个囊泡原子模型的理论分子动力学研究。这些包括每个脂质的面积，膜厚度，囊泡密度，弯曲刚性系数和面积可压缩性。另外，使用闪烁噪声光谱法测量弯曲刚性系数。两种方法产生了非常相似和一致的结果。我们表明，与我们的预期相反，囊泡的固体有序双层的弯曲刚度系数随着脂质转变温度的升高而降低。在平面系统中，这种趋势是相反的。另外，我们已经观察到膜厚度和面积可压缩性的增加以及每个脂质的面积的减少。