Adhesion is a critical cellular process that contributes to migration, apoptosis, differentiation, and division. It is followed by the redistribution of cellular materials at the cell membrane or at the cell-surface interface for cells interacting with surfaces, such as basement membranes. Dynamic and quantitative tracking of changes in cell adhesion mass redistribution is challenging because cells are rapidly moving, inhomogeneous, and nonequilibrium objects, whose physical and mechanical properties are difficult to measure or predict. Here, we report a novel biosensor based microscopy approach termed Photonic Crystal Enhanced Microscopy (PCEM) that enables the movement of cellular materials at the plasma membrane of individual live cells to be dynamically monitored and quantitatively imaged. PCEM utilizes a photonic crystal biosensor surface, which can be coated with arbitrary extracellular matrix materials to facilitate cellular interactions, within a modified brightfield microscope with a low intensity non-coherent light source. Benefiting from the high sensitivity, narrow resonance peak, and tight spatial confinement of the evanescent field atop the photonic crystal biosensor, PCEM enables label-free live cell imaging with high sensitivity and high lateral and axial spatial-resolution, thereby allowing dynamic adhesion phenotyping of single cells without the use of fluorescent tags or stains. We apply PCEM to investigate adhesion and the early stage migration of different types of stem cells and cancer cells. By applying image processing algorithms to analyze the complex spatiotemporal information generated by PCEM, we offer insight into how the plasma membrane of anchorage dependent cells is dynamically organized during cell adhesion. The imaging and analysis results presented here provide a new tool for biologists to gain a deeper understanding of the fundamental mechanisms involved with cell adhesion and concurrent or subsequent migration events.

中文翻译：

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使用光子晶体增强显微镜 (PCEM) 对细胞膜相关有效质量密度进行定量成像

粘附是一个关键的细胞过程，有助于迁移、凋亡、分化和分裂。随后细胞材料在细胞膜或细胞表面界面处重新分布，细胞与表面相互作用，例如基底膜。细胞粘附质量重新分布变化的动态和定量跟踪具有挑战性，因为细胞是快速移动的、不均匀的和非平衡物体，其物理和机械特性难以测量或预测。在这里，我们报告了一种新的基于生物传感器的显微镜方法，称为光子晶体增强显微镜 (PCEM)，它能够动态监测和定量成像单个活细胞质膜上细胞材料的运动。PCEM 利用光子晶体生物传感器表面，在具有低强度非相干光源的改良明场显微镜内，它可以涂上任意的细胞外基质材料，以促进细胞相互作用。受益于光子晶体生物传感器顶部的倏逝场的高灵敏度、窄共振峰和严格的空间限制，PCEM 实现了具有高灵敏度和高横向和轴向空间分辨率的无标记活细胞成像，从而允许动态粘附表型单细胞，无需使用荧光标签或染色剂。我们应用 PCEM 来研究不同类型干细胞和癌细胞的粘附和早期迁移。通过应用图像处理算法分析PCEM产生的复杂时空信息，我们深入了解了贴壁依赖性细胞的质膜在细胞粘附过程中是如何动态组织的。此处呈现的成像和分析结果为生物学家提供了一种新工具，可以更深入地了解与细胞粘附和并发或后续迁移事件相关的基本机制。