Zhu Xinyao, Liu Lanjiao, Wang Zuobin, Liu X
School of Engineering, University of Warwick, Coventry CV4 7AL, UK.
International Research Centre for Nano Handling and Manufacturing of China, Changchun University of Science and Technology, Changchun 130022, China.
Scanning. 2017 Dec 20;2017:8519539. doi: 10.1155/2017/8519539. eCollection 2017.
Nanoindentation technology has proven to be an effective method to investigate the viscoelastic properties of biological cells. The experimental data obtained by nanoindentation are frequently interpreted by Hertz contact model. However, in order to validate Hertz contact model, some studies assume that cells have infinite thickness which does not necessarily represent the real situation. In this study, a rigorous contact model based upon linear elasticity is developed for the interpretation of indentation tests of flattened cells. The cell, normally bonded to the Petri dish, is initially treated as an elastic layer of finite thickness perfectly fixed to a rigid substrate. The theory of linear elasticity is utilized to solve this contact issue and then the solutions are extended to viscoelastic situation which is regarded as a good indicator for mechanical properties of biological cells. To test the present model, AFM-based creep test has been conducted on living human hepatocellular carcinoma cell (SMMC-7721 cell) and its fullerenol-treated counterpart. The results indicate that the present model could not only describe very well the creep behavior of SMMC-7721 cells, but also curb overestimation of the mechanical properties due to substrate effect.
纳米压痕技术已被证明是研究生物细胞粘弹性特性的有效方法。通过纳米压痕获得的实验数据常常采用赫兹接触模型进行解释。然而，为了验证赫兹接触模型，一些研究假设细胞具有无限厚度，而这并不一定代表实际情况。在本研究中，开发了一种基于线弹性的严格接触模型，用于解释扁平细胞的压痕测试。通常与培养皿结合的细胞最初被视为完全固定在刚性基底上的有限厚度弹性层。利用线弹性理论解决该接触问题，然后将解决方案扩展到粘弹性情况，这被视为生物细胞力学特性的良好指标。为了测试当前模型，对活的人肝癌细胞（SMMC - 7721细胞）及其富勒醇处理的对应物进行了基于原子力显微镜的蠕变测试。结果表明，当前模型不仅能够很好地描述SMMC - 7721细胞的蠕变行为，还能抑制由于基底效应导致的力学性能高估。
