Camley Brian A, Brown Frank L H
Department of Physics, University of California, Santa Barbara, California 93106, USA.
Phys Rev E Stat Nonlin Soft Matter Phys. 2011 Aug;84(2 Pt 1):021904. doi: 10.1103/PhysRevE.84.021904. Epub 2011 Aug 4.
Recent experiments suggest that lipid bilayer membranes may be viscoelastic. We present a generalized "Saffman-Einstein" relation that may be used to determine the linear viscoelastic shear modulus from single-bead microrheology experiments on membranes. We show that viscoelastic parameters can also be extracted from membrane domain flicker spectroscopy experiments. Contributions from fluid inertia are expected to be negligible in both microrheology and domain flicker spectroscopy experiments, but can create a "long-time tail" in the membrane velocity autocorrelation function. In a viscous membrane, this tail crosses over from t(-1) at intermediate times, as in a two-dimensional fluid, to t(-3/2) at long times, as in a three-dimensional fluid. If the membrane is viscoelastic, the velocity autocorrelation function may be negative at intermediate times.
最近的实验表明，脂质双分子层膜可能具有粘弹性。我们提出了一个广义的“萨夫曼-爱因斯坦”关系，可用于从对膜的单珠微流变学实验中确定线性粘弹性剪切模量。我们表明，粘弹性参数也可以从膜域闪烁光谱实验中提取。在微流变学和域闪烁光谱实验中，流体惯性的贡献预计可以忽略不计，但会在膜速度自相关函数中产生一个“长时间尾”。在粘性膜中，这个尾在中间时间从二维流体中的(t^{-1})过渡到长时间的三维流体中的(t^{-3/2})。如果膜是粘弹性的，速度自相关函数在中间时间可能为负。
