Improved Atomic Force Microscopy Stiffness Measurements of Nanoscale Liposomes by Cantilever Tip Shape Evaluation.
Improved Atomic Force Microscopy Stiffness Measurements of Nanoscale Liposomes by Cantilever Tip Shape Evaluation.
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DOI：
10.1021/acs.analchem.9b00250
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发表时间：
2019-08
影响因子：
7.4
通讯作者：
Yuki Takechi-Haraya;Y. Goda;K. Izutsu;K. Sakai-Kato
中科院分区：
文献类型：
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作者：
Yuki Takechi-Haraya;Y. Goda;K. Izutsu;K. Sakai-Kato
通过原子力显微镜 (AFM) 测量纳米级脂质体的硬度，研究其与温度、固体基质上的固定和悬臂尖端形状的函数关系。脂质体由饱和脂质和胆固醇组成，硬度值在25-37°C的温度范围内没有变化，并且与固定方法无关。然而，刚度随悬臂尖端形状的变化而变化。因此，通过非盲尖端重建 (NBTR) 方法对 24 个悬臂的尖端形状和纵横比（长度/宽度）进行了评估，该方法使用具有指定尺寸的孤立线结构的尖端表征器。建立了筛选尖端几何形状的标准。通过使用至少三个符合尖端纵横比大于 2.5 和二次尖端形状函数标准的悬臂，证明了相对标准偏差的刚度精度提高了 24 倍。随后发现二棕榈酰磷脂酰胆碱-胆固醇（1:1 摩尔比）和蛋黄磷脂酰胆碱-胆固醇（1:1 摩尔比）脂质体之间的硬度存在显着差异。使用 NBTR 进行尖端分析提高了 AFM 刚度测量的精度，这将能够控制各种应用的纳米级脂质体的机械性能。
The stiffness of nanoscale liposomes, as measured by atomic force microscopy (AFM), was investigated as a function of temperature, immobilization on solid substrates, and cantilever tip shape. The liposomes were composed of saturated lipids and cholesterol, and the stiffness values did not change over the temperature range of 25-37 °C and were independent of immobilization methods. However, the stiffness varied with the tip shape of the cantilever. Therefore, 24 cantilevers were evaluated in terms of tip shape and aspect ratio (length/width) via a nonblind tip reconstruction (NBTR) method that used a tip characterizer with isolated line structures having specified dimensions. A standard for screening the tip geometry was established. A 24-fold improvement in stiffness precision in terms of relative standard deviation was demonstrated by using at least three cantilevers that meet the criteria of having a tip aspect ratio greater than 2.5 and a quadratic tip shape function. A significant difference in stiffness was subsequently revealed between dipalmitoylphosphatidylcholine-cholesterol (1:1 molar ratio) and egg yolk phosphatidylcholine-cholesterol (1:1 molar ratio) liposomes. Tip analysis using NBTR improved the precision of AFM stiffness measurements, which will enable the control of mechanical properties of nanoscale liposomes for various applications.