Department of Biomedical Engineering, University of South Dakota, Sioux Falls, SD, USA.
BioSNTR, Sioux Falls, SD, USA.
Sci Rep. 2018 Feb 13;8(1):2899. doi: 10.1038/s41598-018-21253-9.
Atomic force microscopy (AFM) is an attractive technique for studying biomechanical and morphological changes in live cells. Using real-time AFM monitoring of cellular mechanical properties, spontaneous oscillations in cell stiffness and cell adhesion to the extracellular matrix (ECM) have been found. However, the lack of automated analytical approaches to systematically extract oscillatory signals, and noise filtering from a large set of AFM data, is a significant obstacle when quantifying and interpreting the dynamic characteristics of live cells. Here we demonstrate a method that extends the usage of AFM to quantitatively investigate live cell dynamics. Approaches such as singular spectrum analysis (SSA), and fast Fourier transform (FFT) were introduced to analyze a real-time recording of cell stiffness and the unbinding force between the ECM protein-decorated AFM probe and vascular smooth muscle cells (VSMCs). The time series cell adhesion and stiffness data were first filtered with SSA and the principal oscillatory components were isolated from the noise floor with the computed eigenvalue from the lagged-covariance matrix. Following the SSA, the oscillatory parameters were detected by FFT from the noise-reduced time series data sets and the sinusoidal oscillatory components were constructed with the parameters obtained by FFT.
原子力显微镜（AFM）是一种研究活细胞生物力学和形态变化的有吸引力的技术。通过实时 AFM 监测细胞力学特性，发现细胞刚度和细胞与细胞外基质（ECM）的粘附自发性振荡。然而，缺乏自动分析方法来系统地从大量 AFM 数据中提取振荡信号和噪声滤波，这是在量化和解释活细胞动态特性时的一个重大障碍。在这里，我们展示了一种将 AFM 扩展到定量研究活细胞动力学的方法。引入了奇异谱分析（SSA）和快速傅里叶变换（FFT）等方法来分析细胞刚度的实时记录和 ECM 蛋白修饰的 AFM 探针与血管平滑肌细胞（VSMCs）之间的解附力。时间序列细胞粘附和刚度数据首先用 SSA 过滤，从滞后协方差矩阵计算的特征值中从噪声底部分离出主要振荡分量。在 SSA 之后，通过 FFT 从降噪时间序列数据集中检测到振荡参数，并使用 FFT 获得的参数构建正弦振荡分量。
