Department of Mechanical Engineering, University of Washington, Seattle, WA 98195, USA.
J Mech Behav Biomed Mater. 2010 Apr;3(3):268-77. doi: 10.1016/j.jmbbm.2009.11.001. Epub 2009 Dec 2.
Fundamental to the development and application of biomedical devices is an understanding of the adhesion of cells to substrates. There are many experimental techniques and papers dedicated to the study of cell adhesion. This work aims to elucidate on the cell detachment mechanism in a recently reported cell adhesion measurement experiment by laser-induced stress wave technique. In the experiment the absorption of an Nd:YAG laser pulse generates a stress wave of nanoseconds duration that interacts with and detaches the cell adhered to a Si substrate. Due to the ultra-short timescale involved in the experiment, details of the detachment process were not readily observable. In this work, dynamic finite element method is used to simulate the cell-substrate decohesion process under the laser-induced stress wave loading. The results show that the combined effect of nanosecond stress wave pulse and the specific cell geometry results in a complex stress-strain state along the cell-substrate interface. The principal failure mechanism is large interfacial strains realized from the cell's tendency to spread and elongate on the substrate as a result of substrate acceleration. The cells behave like a soft elastic solid during the detachment process due to the large difference between their characteristic response time and the ultra-short duration of the applied stress wave. Evolution of the cell geometry from hydrophobic to hydrophilic contact results in the same detachment process.
生物医学设备的发展和应用的基础是对细胞与基底附着的理解。有许多实验技术和论文致力于研究细胞附着。这项工作旨在阐明最近报道的激光诱导应力波技术细胞附着测量实验中的细胞脱落机制。在该实验中，纳秒级持续时间的 Nd:YAG 激光脉冲吸收会产生一个应力波，该应力波与附着在 Si 基底上的细胞相互作用并将其分离。由于实验涉及超短时间尺度，因此无法直接观察到脱落过程的细节。在这项工作中，使用动态有限元方法模拟了在激光诱导应力波加载下的细胞-基底脱粘过程。结果表明，纳秒级应力波脉冲和特定细胞几何形状的综合作用导致细胞-基底界面处的复杂应力-应变状态。主要失效机制是由于基底加速导致细胞在基底上扩展和伸长的趋势而产生的界面上的大应变。由于细胞的特征响应时间与施加的应力波的超短持续时间之间存在很大差异，因此细胞在脱落过程中表现为柔软的弹性固体。从疏水接触到亲水接触的细胞几何形状的演变导致了相同的脱落过程。
