Department of Chemical and Biomolecular Engineering, National University of Singapore, 117576, Singapore.
Lab Chip. 2011 Dec 7;11(23):4072-80. doi: 10.1039/c1lc20687g. Epub 2011 Oct 21.
Measurements of mechanical properties of biological cells are of great importance because changes in these properties can be strongly associated with the progression of cell differentiation and cell diseases. Although state of the art methods, such as atomic force microscopy, optical tweezers and micropipette aspiration, have been widely used to measure the mechanical properties of biological cells, all these methods involve direct contact with the cell and the measurements could be affected by the contact or any local deformation. In addition, all these methods typically deduced the Young's modulus of the cells based on their measurements. Herein, we report a new method for fast and direct measurement of the compressibility or bulk modulus of various cell lines on a microchip. In this method, the whole cell is exposed to acoustic radiation force without any direct contact. The method exploits the formation of an acoustic standing wave within a straight microchannel. When the polystyrene beads and cells are introduced into the channel, the acoustic radiation force moves them to the acoustic pressure node and the movement speed is dependent on the compressibility. By fitting the experimental and theoretical trajectories of the beads and the cells, the compressibility of the cells can be obtained. We find that the compressibility of various cancer cells (MCF-7: 4.22 ± 0.19 × 10(-10) Pa(-1), HEPG2: 4.28 ± 0.12 × 10(-10) Pa(-1), HT-29: 4.04 ± 0.16 × 10(-10) Pa(-1)) is higher than that of normal breast cells (3.77 ± 0.09 × 10(-10) Pa(-1)) and fibroblast cells (3.78 ± 0.17 × 10(-10) Pa(-1)). This work demonstrates a novel acoustic-based method for on-chip measurements of cell compressibility, complementing existing methods for measuring the mechanical properties of biological cells.
测量生物细胞的机械性能非常重要，因为这些性能的变化可能与细胞分化和细胞疾病的进展密切相关。尽管原子力显微镜、光镊和微管吸吮等最先进的方法已被广泛用于测量生物细胞的机械性能，但所有这些方法都涉及到与细胞的直接接触，并且测量结果可能会受到接触或任何局部变形的影响。此外，所有这些方法通常都是根据细胞的测量结果来推断出细胞的杨氏模量。在此，我们报告了一种在微芯片上快速直接测量各种细胞系可压缩性或体积模量的新方法。在这种方法中，整个细胞都暴露在声辐射力下，而无需任何直接接触。该方法利用了直微通道内形成的声驻波。当聚苯乙烯珠和细胞被引入通道时，声辐射力将它们移动到声压节点，并且移动速度取决于可压缩性。通过拟合珠和细胞的实验和理论轨迹，可以获得细胞的可压缩性。我们发现，各种癌细胞（MCF-7：4.22 ± 0.19×10^-10 Pa^-1，HEPG2：4.28 ± 0.12×10^-10 Pa^-1，HT-29：4.04 ± 0.16×10^-10 Pa^-1）的可压缩性高于正常乳腺细胞（3.77 ± 0.09×10^-10 Pa^-1）和成纤维细胞（3.78 ± 0.17×10^-10 Pa^-1）。这项工作展示了一种用于芯片上细胞可压缩性测量的新型基于声的方法，补充了现有的用于测量生物细胞机械性能的方法。
