Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland.
Institute of Physical Chemistry, Polish Academy of Sciences, Kasprzaka 44/52, 01-224 Warsaw, Poland; Department of Chemistry, University of Guelph, 50 Stone Road East, Guelph, Ontario N1G 2W1, Canada.
Biochim Biophys Acta Biomembr. 2020 Sep 1;1862(9):183347. doi: 10.1016/j.bbamem.2020.183347. Epub 2020 May 11.
Topography and nanomechanical properties of the supported 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) single bilayer in the ripple phase were investigated by atomic force microscopy with the use of PeakForce Quantitative Nanomechanical Mapping (PF-QNM) mode under liquid conditions. The DMPC single bilayer was deposited on the mica surface by Langmuir-Blodgett and Langmuir-Schaefer techniques combined. Next, the sample was stored overnight at 4 °C under buffer solution (pH = 7.6) in the presence of tris(hydroxymethyl)aminomethane, (Tris), and then, AFM imaging was performed at 21 °C using the same buffer. The AFM topography images revealed the presence of a periodic structure with an average wavelength of 96.0 ± 7.8 nm and an average amplitude of 0.97 ± 0.03 nm. This macro-ripple structure was asymmetric and formed by long ripples composed of two stripes of different heights. The changes in topography were accompanied by local changes in the Young's modulus, which indicate that the nanomechanical properties of the bilayer are not evenly distributed, namely, the higher stripes are characterized by a lower Young's modulus than that calculated for lower stripes of the ripples. This indicates that the ripple phase is composed of phospholipid molecules of periodically changed orientation and conformation characteristic for fluid-like and gel-like state of DMPC.
采用原子力显微镜，在液相等离子体条件下，利用 PeakForce Quantitative Nanomechanical Mapping (PF-QNM) 模式，研究了波纹相下支撑的 1,2-二肉豆蔻酰基-sn-甘油-3-磷酸胆碱（DMPC）单层的形貌和纳米力学性质。DMPC 单层通过 Langmuir-Blodgett 和 Langmuir-Schaefer 技术沉积在云母表面上。然后，将样品在缓冲液（pH = 7.6）中在 4°C 下储存过夜，存在三羟甲基氨基甲烷（Tris），然后在相同的缓冲液中在 21°C 下进行 AFM 成像。AFM 形貌图像显示存在具有平均波长为 96.0 ± 7.8nm 和平均振幅为 0.97 ± 0.03nm 的周期性结构。这种宏观波纹结构是不对称的，由两条不同高度条纹组成的长波纹形成。形貌的变化伴随着杨氏模量的局部变化，这表明双层的纳米力学性质不是均匀分布的，即较高的条纹的杨氏模量比波纹较低条纹的计算值低。这表明波纹相由周期性改变取向和构象的磷脂分子组成，其特征为 DMPC 的液态和凝胶态。
