期刊
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
卷 107, 期 -, 页码 284-293出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.jmps.2017.07.007
关键词
Mammalian cytoplasm; Microrheology; Optical tweezers; Non-equilibrium; Cell mechanics
资金
- d'Arbeloff career development fund at Department of Mechanical Engineering at MIT
Living cells are intrinsically non-equilibrium systems. They are driven out of equilibrium by the activity of the molecular motors and other enzymatic processes. This activity along with the ever present thermal agitation results in intracellular fluctuations inside the cytoplasm. In analogy to Brownian motion, the material property of the cytoplasm also influences the characteristics of these fluctuations. In, this paper, through a combination of experimentation and theoretical analysis, we show that intracellular fluctuations are indeed due to non thermal forces at relatively long time-scales, however, are dominated solely by thermal forces at relatively short time-scales. Thus, the cytoplasm of living mammalian cells behaves as an equilibrium material at short time-scales. The mean square displacement of these intracellular fluctuations scales inversely with the cytoplasmic shear modulus in this short time-scale equilibrium regime, and is inversely proportional to the square of the cytoplasmic shear modulus in the long time-scale out-of-equilibrium regime. Furthermore, we deploy passive microrheology based on these fluctuations to extract the mechanical property of the cytoplasm at the high-frequency regime. We show that the cytoplasm of living mammalian cells is a weak elastic gel in this regime; this is in an excellent agreement with an independent micromechanical measurement using optical tweezers. (C) 2017 Elsevier Ltd. All rights reserved.
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