Quantitative evaluation of visco-elastic distribution of living cells using scanning probe microscopy

要将细胞迁移理解为一个完整的机械系统，需要对活细胞的力学特性进行实验研究。提出了一种基于扫描探针显微镜的力调制方式，为高时空分辨率的活细胞刚度测量提供了一种有效的方法。然而，在液体环境中，通过力调制模式获得的细胞刚度往往是令人难以置信的。为了解决这一问题，对微悬臂梁的一维动力学方程进行了数值分析，该方程考虑了样品的粘弹性和液体的粘度，以评估悬臂梁与液体中的活细胞接触时的相移与幅度调制之间的关系。对于各种粘弹性试件，分别进行了悬臂梁与试件周期性接触和不与试件接触时的振动分析。在此基础上，建立了悬臂梁振动特性与试件粘弹性特性之间的定量关系。利用这些结果，新开发了活细胞粘弹性特性分析系统，展示了活细胞的力学特性。

Understanding cellular migration as an integrated mechanical system requires an experimental investigations on mechanical properties of living cells. Force modulation mode with SPM is proposed as a useful method fur measuring stiffness of living cells with high temporal and spatial resolution. However, in liquid environment, cellular stiffness obtained by force modulation mode is often incredible.To clear this problem, numerical analysis of the 1-dimensional dynamic equation of a-micro cantilever, which concern about the visco-elastic property of the sample and viscosity of the liquid, is carried out to evaluate the relations between phase shift and amplitude modulations when the cantilever contacts with the living cells in a liquid. Also, the vibration analysis is performed when the cantilever periodically contact and not contact to the sample for various visco-elastic samples. Based on those results, the quantitative relations between vibration property of the cantilever and visco-elastic property of the sample are derived. Using these results, analysis system of the visco-elastic property for living cells is newly developed and the mechanical property of the living cells are demonstrated.