Time resolved membrane fluctuation spectroscopy
Time resolved membrane fluctuation spectroscopy
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DOI：
10.1039/c2sm00001f
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发表时间：
2012-01-01
期刊：
影响因子：
3.4
通讯作者：
Sykes, Cecile
中科院分区：
文献类型：
--
作者：
Betz, Timo;Sykes, Cecile
探测磷脂膜的机械性能是仿生膜系统以及活细胞系统的基本表征步骤。一种常见的方法依赖于热膜波动的分析，这已经在视频闪烁光谱中实现。在这里，我们提出了一种新的光学方法，直接测量的动态膜波动与nm和μ s的分辨率，从而提供访问的弯曲模量κ和膜张力σ的测量时间为10秒。我们的方法允许观察脂质体的双层膜波动，并计算尚未报道的频率> 50 Hz和振幅< 10 nm的功率谱密度。记录的数据与Helfrich膜理论在40年的频率（0.1 Hz-1000 Hz）。然而，我们发现了一个系统的高估的缓冲液粘度，这不能简单地解释为测量误差，但揭示了一个效果，这是不能解释的经典理论膜动力学，因此表明，新的物理必须在所观察到的频率和振幅范围内开发。实验方法是很容易重现的任何光镊设置配备了象限光电二极管位置检测传感器。
Probing the mechanical properties of phospholipid membranes is a fundamental characterization step for biomimetic membrane systems as well as for living cellular systems. A common method relies on the analysis of thermal membrane fluctuations, which has been implemented in video flicker spectroscopy. Here we present a new optical method that directly measures the dynamics of membrane fluctuations with nm and mu s resolution, thus providing access to the bending modulus kappa and the membrane tension sigma for measurement times of 10 s. Our method allows the observation of bilayer membrane fluctuations of liposomes and the calculation of the power spectral density in yet unreported regimes of frequencies > 50 Hz and amplitudes < 10 nm. The recorded data are in agreement with the Helfrich membrane theory over 4 decades of frequencies (0.1 Hz-1000 Hz). However, we find a systematic overestimation of the buffer viscosity, which can not be simply explained by measurement errors, but unveils an effect that is not explained by the classical theory for membrane dynamics, and hence suggests that new physics must be developed in the observed frequency and amplitude range. The experimental method is easily reproducible on any optical tweezer setup equipped with a quadrant photodiode position detection sensor.