Berret J-F
Matière et Systèmes Complexes, UMR 7057 CNRS Université Denis Diderot Paris-VII, Bâtiment Condorcet, 10 rue Alice Domon et Léonie Duquet, 75205 Paris, France.
Nat Commun. 2016 Jan 5;7:10134. doi: 10.1038/ncomms10134.
When submitted to a magnetic field, micron-size wires with superparamagnetic properties behave as embedded rheometers and represent interesting sensors for microrheology. Here we use rotational magnetic spectroscopy to measure the shear viscosity of the cytoplasm of living cells. We address the question of whether the cytoplasm is a viscoelastic liquid or an elastic gel. The main result of the study is the observation of a rotational instability between a synchronous and an asynchronous regime of rotation, found for murine fibroblasts and human cancer cells. For wires of susceptibility 3.6, the transition occurs in the range 0.01-1 rad s(-1). The determination of the shear viscosity (10-100 Pa s) and elastic modulus (5-20 Pa) confirms the viscoelastic character of the cytoplasm. In contrast to earlier studies, it is concluded that the interior of living cells can be described as a viscoelastic liquid, and not as an elastic gel.
当置于磁场中时，具有超顺磁特性的微米级导线表现为嵌入式流变仪，是用于微流变学的有趣传感器。在此，我们使用旋转磁谱来测量活细胞细胞质的剪切粘度。我们探讨了细胞质是粘弹性液体还是弹性凝胶这一问题。该研究的主要结果是观察到在小鼠成纤维细胞和人类癌细胞中，同步旋转和异步旋转状态之间存在旋转不稳定性。对于磁化率为3.6的导线，转变发生在0.01 - 1弧度每秒（-1）的范围内。剪切粘度（10 - 100帕斯卡秒）和弹性模量（5 - 20帕斯卡）的测定证实了细胞质的粘弹性特征。与早期研究不同的是，得出的结论是活细胞内部可描述为粘弹性液体，而非弹性凝胶。
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