Department of Mechanical and Industrial Engineering, University of Toronto, Toronto, Ontario M5S 3G8, Canada.
Biomicrofluidics. 2012 Aug 13;6(3):34112. doi: 10.1063/1.4746249. Print 2012 Sep.
The specific membrane capacitance (SMC) is an electrical parameter that correlates with both the electrical activity and morphology of the plasma membrane, which are physiological markers for cellular phenotype and health. We have developed a microfluidic device that enables impedance spectroscopy measurements of the SMC of single biological cells. Impedance spectra induced by single cells aspirated into the device are captured over a moderate frequency range (5 kHz-1 MHz). Maximum impedance sensitivity is achieved using a tapered microfluidic channel, which effectively routes electric fields across the cell membranes. The SMC is extracted by curve-fitting impedance spectra to an equivalent circuit model. From our measurement, acute myeloid leukemia (AML) cells are found to exhibit larger SMC values in hypertonic solutions as compared with those in isotonic solutions. In addition, AML cell phenotypes (AML2 and NB4) exhibiting varying metastatic potential yield distinct SMC values (AML2: 16.9 ± 1.9 mF/m(2) (n = 23); NB4: 22.5 ± 4.7 mF/m(2) (n = 23)). Three-dimensional finite element simulations of the microfluidic device confirm the feasibility of this approach.
特定膜电容（SMC）是与质膜的电活动和形态相关的电参数，质膜的电活动和形态是细胞表型和健康的生理标志物。我们开发了一种微流控装置，能够对单个生物细胞的 SMC 进行阻抗谱测量。通过将单个细胞吸入装置中，捕获在中等频率范围内（5 kHz-1 MHz）的阻抗谱。使用锥形微流道实现最大的阻抗灵敏度，该微流道可有效地将电场引导穿过细胞膜。通过将阻抗谱拟合到等效电路模型来提取 SMC。从我们的测量结果来看，与等渗溶液相比，急性髓系白血病（AML）细胞在高渗溶液中表现出更大的 SMC 值。此外，表现出不同转移潜力的 AML 细胞表型（AML2 和 NB4）产生不同的 SMC 值（AML2：16.9 ± 1.9 mF/m2（n = 23）；NB4：22.5 ± 4.7 mF/m2（n = 23））。微流控装置的三维有限元模拟证实了这种方法的可行性。
