We studied the lateral forces arising during the vertical indentation of the cell membrane by an optically trapped microbead, using back focal plane interferometry to determine force components in all directions. We analyzed the cell-microbead interaction and showed that indeed the force had also lateral components. Using the Hertz model, we calculated and compared the elastic moduli resulting from the total and vertical forces, showing that the differences are important and the total force should be considered. To confirm our results we analyzed cells from two breast cancer cell lines: MDA-MB-231 and HBL-100, known to have different cancer aggressiveness and hence stiffness.

我们使用后焦平面干涉测量法确定了所有方向的力分量，研究了由光学捕获的微珠在细胞膜的垂直压痕过程中产生的横向力。我们分析了细胞-微珠的相互作用，并表明该力确实也具有侧向分量。使用赫兹模型，我们计算并比较了总力和垂直力产生的弹性模量，表明差异很重要，应考虑总力。为了证实我们的结果，我们分析了来自两种乳腺癌细胞系的细胞：MDA-MB-231和HBL-100，已知它们具有不同的癌症侵袭性并因此具有不同的硬度。