Janik Alexander, Neckernuss Tobias, Gottschalk Kay-E, Marti Othmar
Institute for Experimental Physics, University of Ulm, Albert-Einstein-Allee 11, 89081 Ulm, Germany.
Soft Matter. 2025 Jul 30;21(30):6144-6162. doi: 10.1039/d5sm00009b.
The lack of quantitative agreement between different techniques and publications has been an open issue in cell rheology for many years. Major differences in experimental design - and thus potential sources of the discrepancy - include the magnitude and lateral length scale of force application. To address these issues, we have developed an optical stretcher capable of extracting viscoelastic parameters from adherent cells while applying very low forces of a few pN and deformations of a few nm in a contact-free manner. This paper outlines the potential and limitations of such a setup. The latter include the necessity of reference measurements with the cells in an index-matched medium. It is to our knowledge the first time that adherent cells have been characterized with an optical stretching setup capable of quantitative mechanical measurements. Furthermore, a meta-analysis is conducted with papers measuring the same cell lines by AFM indentation and evaluating the results with the same power-law model. The apparent stiffness values obtained vary by two orders of magnitude, but turn out to be strongly correlated with contact radius as well as applied mechanical stress. The values from optical stretching obtained at low stress and deformation fit into that picture.
多年来，不同技术和出版物之间缺乏定量一致性一直是细胞流变学领域的一个悬而未决的问题。实验设计上的重大差异——也就是差异的潜在来源——包括施力的大小和横向长度尺度。为了解决这些问题，我们开发了一种光学拉伸仪，它能够以非接触方式在施加几皮牛的极低力和几纳米的变形时，从贴壁细胞中提取粘弹性参数。本文概述了这种装置的潜力和局限性。局限性包括需要在折射率匹配的介质中对细胞进行参考测量。据我们所知，这是首次使用能够进行定量力学测量的光学拉伸装置对贴壁细胞进行表征。此外，我们对通过原子力显微镜压痕测量相同细胞系并使用相同幂律模型评估结果的论文进行了荟萃分析。获得的表观刚度值相差两个数量级，但结果显示与接触半径以及施加的机械应力密切相关。在低应力和变形条件下通过光学拉伸获得的值也符合这一情况。
