Park Kidong, Jang Jaesung, Irimia Daniel, Sturgis Jennifer, Lee James, Robinson J Paul, Toner Mehmet, Bashir Rashid
Birck Nanotechnology Center, Purdue University, West Lafayette, IN 47907, USA.
Lab Chip. 2008 Jul;8(7):1034-41. doi: 10.1039/b803601b. Epub 2008 Jun 11.
The size of a cell is a fundamental physiological property and is closely regulated by various environmental and genetic factors. Optical or confocal microscopy can be used to measure the dimensions of adherent cells, and Coulter counter or flow cytometry (forward scattering light intensity) can be used to estimate the volume of single cells in a flow. Although these methods could be used to obtain the mass of single live cells, no method suitable for directly measuring the mass of single adherent cells without detaching them from the surface is currently available. We report the design, fabrication, and testing of 'living cantilever arrays', an approach to measure the mass of single adherent live cells in fluid using silicon cantilever mass sensor. HeLa cells were injected into microfluidic channels with a linear array of functionalized silicon cantilevers and the cells were subsequently captured on the cantilevers with positive dielectrophoresis. The captured cells were then cultured on the cantilevers in a microfluidic environment and the resonant frequencies of the cantilevers were measured. The mass of a single HeLa cell was extracted from the resonance frequency shift of the cantilever and was found to be close to the mass value calculated from the cell density from the literature and the cell volume obtained from confocal microscopy. This approach can provide a new method for mass measurement of a single adherent cell in its physiological condition in a non-invasive manner, as well as optical observations of the same cell. We believe this technology would be very valuable for single cell time-course studies of adherent live cells.
细胞大小是一项基本的生理特性，受到各种环境和遗传因素的严格调控。光学显微镜或共聚焦显微镜可用于测量贴壁细胞的尺寸，库尔特计数器或流式细胞仪（前向散射光强度）可用于估计流动中单细胞的体积。虽然这些方法可用于获取单个活细胞的质量，但目前尚无适用于在不将单个贴壁细胞从表面分离的情况下直接测量其质量的方法。我们报告了“活体悬臂阵列”的设计、制造和测试，这是一种使用硅悬臂质量传感器测量流体中单个贴壁活细胞质量的方法。将HeLa细胞注入带有功能化硅悬臂线性阵列的微流控通道中，随后通过正介电泳将细胞捕获在悬臂上。然后在微流控环境中在悬臂上培养捕获的细胞，并测量悬臂的共振频率。从悬臂的共振频率偏移中提取单个HeLa细胞的质量，发现其接近根据文献中的细胞密度和通过共聚焦显微镜获得的细胞体积计算出的质量值。这种方法可以以非侵入性方式为在生理条件下测量单个贴壁细胞的质量提供一种新方法，以及对同一细胞进行光学观察。我们相信这项技术对于贴壁活细胞的单细胞时间进程研究将非常有价值。
