Department of Mechanical Engineering, National University of Singapore, Singapore.
Biomech Model Mechanobiol. 2010 Oct;9(5):563-72. doi: 10.1007/s10237-010-0197-7. Epub 2010 Feb 24.
Accurate quantification of the mechanical properties of living cells requires the combined use of experimental techniques and theoretical models. In this paper, we investigate the viscoelastic response of suspended NIH 3T3 fibroblasts undergoing micropipette aspiration using power-law rheology model. As an important first step, we examine the pipette size effect on cell deformation and find that pipettes larger than ~7 μm are more suitable for bulk rheological measurements than smaller ones and the cell can be treated as effectively continuum. When the large pipettes are used to apply a constant pressure to a cell, the creep deformation is better fitted with the power-law rheology model than with the liquid drop or spring-dashpot models; magnetic twisting cytometry measurement on the rounded cell confirms the power-law behavior. This finding is further extended to suspended cells treated with drugs targeting their cytoskeleton. As such, our results suggest that the application of relatively large pipettes can provide more effective assessment of the bulk material properties as well as support application of power-law rheology to cells in suspension.
准确量化活细胞的力学性能需要实验技术和理论模型的结合使用。本文采用幂律流变学模型研究了悬浮 NIH 3T3 成纤维细胞在微管吸吮过程中的粘弹性响应。作为重要的第一步，我们研究了微管尺寸对细胞变形的影响，发现大于~7μm 的微管比小尺寸微管更适合进行整体流变学测量，并且细胞可以被视为有效的连续体。当使用大微管对细胞施加恒定压力时，蠕变变形与幂律流变学模型的拟合优于液滴或弹簧-阻尼器模型；对圆形细胞进行的磁扭转细胞测量证实了幂律行为。这一发现进一步扩展到了用靶向细胞骨架的药物处理的悬浮细胞。因此，我们的结果表明，应用相对较大的微管可以更有效地评估整体材料特性，并支持将幂律流变学应用于悬浮细胞。
