Drabik Dominik, Przybyło Magda, Chodaczek Grzegorz, Iglič Aleš, Langner Marek
Laboratory for Biophysics of Lipid Aggregates, Department of Biomedical Engineering, Wrocław University of Technology, 50-377 Wrocław, Pl. Grunwaldzki 13, Poland; Lipid Systems sp. z. o. o., ul. Duńska 9, 54-427 Wrocław, Poland.
Laboratory for Biophysics of Lipid Aggregates, Department of Biomedical Engineering, Wrocław University of Technology, 50-377 Wrocław, Pl. Grunwaldzki 13, Poland; Lipid Systems sp. z. o. o., ul. Duńska 9, 54-427 Wrocław, Poland.
Biochim Biophys Acta. 2016 Feb;1858(2):244-52. doi: 10.1016/j.bbamem.2015.11.020. Epub 2015 Nov 23.
Lipid bilayer is the main constitutive element of biological membrane, which confines intracellular space. The mechanical properties of biological membranes may be characterized by various parameters including membrane stiffness or membrane bending rigidity, which can be measured using flicker noise spectroscopy. The flicker noise spectroscopy exploits the spontaneous thermal undulations of the membrane. The method is based on the quantitative analysis of a series of microscopic images captured during thermal membrane fluctuations. Thus, measured bending rigidity coefficient depends on the image quality as well as the selection of computational tools for image processing and mathematical model used. In this work scanning and spinning disc confocal microscopies were used to visualize fluctuating membranes of giant unilamellar vesicles. The bending rigidity coefficient was calculated for different acquisition modes, using different fluorescent probes and different image processing methods. It was shown that both imaging approaches gave similar bending coefficient values regardless of acquisition time. Using the developed methodology the effect of fluorescent probe type and aqueous phase composition on the value of the membrane bending rigidity coefficient was measured. Specifically it was found that the bending rigidity coefficient of DOPC bilayer in water is smaller than that determined for POPC membrane. It has been found that the POPC and DOPC bending rigidities coefficient in sucrose solution was lower than that in water. Fluorescence imaging makes possible the quantitative analysis of membrane mechanical properties of inhomogeneous membrane.
脂质双层是生物膜的主要组成成分，它界定了细胞内空间。生物膜的力学性质可以通过包括膜刚度或膜弯曲刚度在内的各种参数来表征，这些参数可以使用闪烁噪声光谱法进行测量。闪烁噪声光谱法利用了膜的自发热波动。该方法基于对热膜波动过程中捕获的一系列微观图像的定量分析。因此，测得的弯曲刚度系数取决于图像质量以及用于图像处理的计算工具的选择和所使用的数学模型。在这项工作中，使用扫描共聚焦显微镜和旋转盘共聚焦显微镜来观察巨型单层囊泡的波动膜。使用不同的荧光探针和不同的图像处理方法，针对不同的采集模式计算弯曲刚度系数。结果表明，无论采集时间如何，两种成像方法给出的弯曲系数值相似。使用所开发的方法，测量了荧光探针类型和水相组成对膜弯曲刚度系数值的影响。具体而言，发现水中DOPC双层的弯曲刚度系数小于POPC膜的弯曲刚度系数。已经发现，蔗糖溶液中POPC和DOPC的弯曲刚度系数低于水中的弯曲刚度系数。荧光成像使得对不均匀膜的膜力学性质进行定量分析成为可能。
