School of Mechanical & Systems Engineering, Newcastle University, Newcastle Upon Tyne, UK.
J Biomech. 2012 Nov 15;45(16):2810-6. doi: 10.1016/j.jbiomech.2012.08.037. Epub 2012 Sep 25.
The viscoelastic properties of the living cells are for quantifying the biomechanical effects of drug treatment, diseases and aging. Nanoindentation techniques have proven effective to characterize the viscoelastic properties of living cells. However, most studies utilized the Hertz contact model and assumed the Heaviside step loading, which does not represent real tests. Therefore, new mathematical models have been developed to determine the viscoelastic properties of the cells for nanoindentation tests. Finite element method was used to determine the empirical correction parameter in the mathematical model to account for large deformation, in which case the combined effect of finite lateral and vertical dimensions of the cell is essential. The viscoelastic integral operator was used to account for the realistic deformation rate. The predictive model captures the mechanical responses of the cells observed from previous experimental study. This work has demonstrated that the new model consistently predicts viscoelastic properties for both ramping and stress relaxation periods, which cannot be achieved by the commonly used models. Utilization of this new model can enrich the experimental cell mechanics in interpretation of nanoindentation of cells.
活细胞的黏弹性性质可用于量化药物处理、疾病和衰老对生物力学的影响。纳米压痕技术已被证明可有效用于描述活细胞的黏弹性性质。然而，大多数研究都利用赫兹接触模型并假设使用阶跃加载，这并不代表真实的测试。因此，已经开发了新的数学模型来确定纳米压痕试验中细胞的黏弹性性质。有限元法用于确定数学模型中的经验修正参数，以考虑大变形，在这种情况下，细胞的有限横向和纵向尺寸的综合效应是必不可少的。黏弹性积分算子用于考虑实际的变形率。预测模型捕捉到了之前实验研究中观察到的细胞的力学响应。这项工作表明，新模型能够一致地预测斜坡和应力松弛阶段的黏弹性性质，而这是常用模型无法实现的。该新模型的应用可以丰富细胞纳米压痕实验的力学解释。
