Department of Soft Condensed Matter, Institute of Physical Chemistry PAS, Kasprzaka 44/52 01-224 Warsaw, Poland.
Nano Lett. 2011 May 11;11(5):2157-63. doi: 10.1021/nl2008218. Epub 2011 Apr 22.
We present a scaling formula for size-dependent viscosity coefficients for proteins, polymers, and fluorescent dyes diffusing in complex liquids. The formula was used to analyze the mobilities of probes of different sizes in HeLa and Swiss 3T3 mammalian cells. This analysis unveils in the cytoplasm two length scales: (i) the correlation length ξ (approximately 5 nm in HeLa and 7 nm in Swiss 3T3 cells) and (ii) the limiting length scale that marks the crossover between nano- and macroscale viscosity (approximately 86 nm in HeLa and 30 nm in Swiss 3T3 cells). During motion, probes smaller than ξ experienced matrix viscosity: η(matrix) ≈ 2.0 mPa·s for HeLa and 0.88 mPa·s for Swiss 3T3 cells. Probes much larger than the limiting length scale experienced macroscopic viscosity, η(macro) ≈ 4.4 × 10(-2) and 2.4 × 10(-2) Pa·s for HeLa and Swiss 3T3 cells, respectively. Our results are persistent for the lengths scales from 0.14 nm to a few hundred nanometers.
我们提出了一种用于描述蛋白质、聚合物和荧光染料在复杂液体中扩散时尺寸相关粘度系数的标度公式。该公式用于分析不同大小探针在 HeLa 和 Swiss 3T3 哺乳动物细胞中的迁移率。该分析揭示了细胞质中的两个长度尺度：（i）相关长度 ξ（在 HeLa 中约为 5nm，在 Swiss 3T3 中约为 7nm）和（ii）标志纳米和宏观粘度之间交叉的极限长度尺度（在 HeLa 中约为 86nm，在 Swiss 3T3 中约为 30nm）。在运动过程中，小于 ξ 的探针经历了基质粘度：η（基质）≈2.0 mPa·s（对于 HeLa）和 0.88 mPa·s（对于 Swiss 3T3）。远大于极限长度尺度的探针经历宏观粘度，η（宏观）≈4.4×10(-2) 和 2.4×10(-2) Pa·s（对于 HeLa 和 Swiss 3T3）。我们的结果在 0.14nm 到几百纳米的长度尺度上是一致的。
