INDENTATION WITH ATOMIC FORCE MICROSCOPY

原子力显微镜(AFM)的纳米压痕具有敏感度和 提供所需的区域力学性能数据的决议 活细胞。然而，对结果的解释因 AFM探头尖端的金字塔形状，其尺寸相对于 压痕深度。帮助实现这一目标的全部潜力 技术，这项提案的总体目标是执行彻底的 有限压痕问题的工程分析，强调了 相对压痕深度和尖端几何形状的影响，并使用 指导AFM压痕研究材料力学性能的研究结果 活细胞。将进行一系列系统的有限元模拟 用于指定流行的简单化方法用于 AFM分析是有效的，并针对另外两个具体目标进行测试 压痕是否可以用来识别材料的非均质性 线性和各向异性。第四个具体目标是同时利用 细胞的静态拉伸和AFM鉴定以验证假设 静息心脏成纤维细胞具有非线性和各向同性材料 属性，但它们在肌动蛋白重定向后变为各向异性 应力纤维对循环拉伸的响应。

Nano-indentation by atomic force microscopy (AFM) has the sensitivity and resolution to provide needed data on regional mechanical properties of living cells. However, interpretation of the results is complicated by the pyramidal shape of the AFM probe tip, and its small size relative to the depth of indentation. To help realize the full potential of this technology, the overall goal of this proposal is to perform a thorough engineering analysis of the finite-indentation problem, emphasizing the effects of relative indentation depth and tip geometry, and use the findings to guide AFM indentation studies on the mechanical properties of living cells. A systematic series of finite element simulations will be used to specify the conditions for which popular simplistic methods for AFM analysis are valid, and to address two other specific aims testing whether indentations can be used to identify material heterogeneity, non- linearity, and anisotropy. A fourth specific aim utilizes simultaneous static stretch and AFM identification of cells to test the hypothesis that resting cardiac fibroblasts have non-linear and isotropic material properties, but they become anisotropic after reorientation of actin stress fibers in response to cyclic stretch.