Janshoff A, Wegener J, Sieber M, Galla H J
Institute of Biochemistry, Westfälische Wilhelms-University, Münster, Germany.
Eur Biophys J. 1996;25(2):93-103. doi: 10.1007/s002490050021.
The viscoelastic behavior of epithelial cells (MDCK-I and MDCK-II) grown on AT-cut quartz crystals with a fundamental resonance at 5 MHz was investigated by impedance spectroscopy. Using the electromechanical model recently derived by Martin et al. [(1991) Anal Chem 63: 2272-2281] for Newtonian liquids in contact with shear wave resonators we quantified the viscous damping arising from the adherent cells by fitting the impedance data with a modified Butterworth-Van Dyke circuit in the region of the resonance frequency. Impedance spectroscopy was additionally performed in the frequency range from 1 Hz to 1 MHz to scrutinize the passive electrical properties of the epithelial cell layers using an additional platinum electrode. These data allow one to document the cell layers' integrity as well as the electrode coverage. We were able to confirm that the presence of a cell-layer mainly increases damping of the shear wave and does not exhibit a pure mass-load behavior. These findings were supported by the discovery that the inductance L in the electromechanical model was less influenced by the cell-layer than the resistance R. The apparent cell-viscosities determined by our method are 0.097 poise for MDCK-I and 0.142 poise for MDCK-II cell-layers. These low apparent viscosities may be explained in terms of a considerable spacing between the cells immobilized via their focal contacts and the quartz surface.
采用阻抗谱研究了生长在基频为5 MHz的AT切割石英晶体上的上皮细胞（MDCK - I和MDCK - II）的粘弹性行为。利用Martin等人[（1991年）《分析化学》63：2272 - 2281]最近推导的用于与剪切波谐振器接触的牛顿液体的机电模型，我们通过在谐振频率区域用改进的巴特沃斯 - 范戴克电路拟合阻抗数据，量化了附着细胞产生的粘性阻尼。另外，在1 Hz至1 MHz的频率范围内进行阻抗谱分析，使用额外的铂电极来仔细研究上皮细胞层的无源电学性质。这些数据能够记录细胞层的完整性以及电极覆盖情况。我们能够证实细胞层的存在主要增加了剪切波的阻尼，并且不表现出纯质量负载行为。机电模型中的电感L受细胞层的影响小于电阻R这一发现支持了这些结果。通过我们的方法测定的MDCK - I细胞层和MDCK - II细胞层的表观细胞粘度分别为0.097泊和0.142泊。这些低表观粘度可以通过经由其粘着斑固定的细胞与石英表面之间存在相当大的间距来解释。
