Rheology and microrheology of semiflexible polymer solutions: Actin filament networks

被引:105
作者
Xu, JY [1 ]
Palmer, A [1 ]
Wirtz, D [1 ]
机构
[1] Johns Hopkins Univ, Dept Chem Engn, Baltimore, MD 21218 USA
关键词
D O I
10.1021/ma9717754
中图分类号
O63 [高分子化学(高聚物)];
学科分类号
070305 ; 080501 ; 081704 ;
摘要
We report a systematic study of the linear rheology of solutions of model semiflexible polymers, actin filaments (F-actin), using mechanical rheometry, diffusing wave spectroscopy (DWS), and video-based single-particle tracking microrheology. For pure actin at c = 24 mu M and after full polymerization, the elastic and loss moduli still increase with time as G'(t) proportional to t(0.25+/-0.02) and G "(t) proportional to t(0.15+/-0.03), when measured at 1 rad/s, during network formation and reach a plateau after 12 h. At equilibrium, the linear small-frequency elastic modulus has a small magnitude, G(p)' = 14 +/- 3 dynes/cm(2). The magnitude of G(p)', depends weakly on concentration as G(p)'(c) proportional to c(1.2+/-0.2), with an exponent much smaller than for flexible polymers. At large concentrations, F-actin network becomes a liquid crystal and G', is independent of concentration Using the large bandwidth of DWS, we show that; the high-frequency viscoelastic modulus of F-actin solutions varies with the shear frequency as \G*(omega)\ proportional to omega(0.78+/-0.10) for both the isotropic phase and liquid crystalline phase. These results are in good agreement with a recent model of semiflexible polymer solutions (the "curvature-stress" model) and reflect the finite rigidity of F-actin.
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页码:6486 / 6492
页数:7
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