Yoon Young-Zoon, Kotar Jurij, Yoon Gilwon, Cicuta Pietro
Cavendish Laboratory and Nanoscience Center, University of Cambridge, Cambridge CB30HE, UK.
Phys Biol. 2008 Aug 13;5(3):036007. doi: 10.1088/1478-3975/5/3/036007.
We measure the dynamical mechanical properties of human red blood cells. A single cell response is measured with optical tweezers. We investigate both the stress relaxation following a fast deformation and the effect of varying the strain rate. We find a power-law decay of the stress as a function of time, down to a plateau stress, and a power-law increase of the cell's elasticity as a function of the strain rate. Interestingly, the exponents of these quantities violate the linear superposition principle, indicating a nonlinear response. We propose that this is due to the breaking of a fraction of the crosslinks during the deformation process. The soft glassy rheology model accounts for the relation between the exponents we observe experimentally. This picture is consistent with recent models of bond remodeling in the red blood cell's molecular structure. Our results imply that the blood cell's mechanical behavior depends critically on the deformation process.
我们测量了人类红细胞的动态力学特性。用光学镊子测量单个细胞的响应。我们研究了快速变形后的应力松弛以及应变率变化的影响。我们发现应力随时间呈幂律衰减，直至达到平台应力，并且细胞弹性随应变率呈幂律增加。有趣的是，这些量的指数违反了线性叠加原理，表明存在非线性响应。我们认为这是由于在变形过程中一部分交联键断裂所致。软玻璃流变学模型解释了我们实验观察到的指数之间的关系。这一情况与红细胞分子结构中键重塑的最新模型一致。我们的结果表明血细胞的力学行为严重依赖于变形过程。
