Measuring transport properties of cell membranes by a PDMS microfluidic device with controllability over changing rate of extracellular solution

The transport of water and chemicals across cell membranes plays an important role in cell biology and in cryopreservation. In this study, a polydimethylsiloxane (PDMS) microfluidic device with hydrodynamic switching is developed to change the extracellular solution at controllable rates in measuring transport properties of cell membranes. To demonstrate the capability of the PDMS microfluidic device, the volume response of trapped chondrocytes to the change in extracellular osmolality is recorded and analyzed to determine the hydraulic conductivity, one of the transport properties of cell membranes. The results show that hydraulic switching is a convenient and reliable method for controlling the switching time constant of the extracellular solution. The switching time constant increases with the increase in the aspiration rate of the syringe pump, which induces the hydrodynamic switching. The two membrane hydraulic conductivities of fresh chondrocytes, measured at two different switching time constants, are statistically identical (t-test, confidence level = 95%), which indicates a high credibility for the method developed in this study. The PDMS device reported here represents the first successful use of hydrodynamic switching in a microfluidic device to control the changing rate of extracellular solutions in the measurement of membrane properties. (C) 2014 Elsevier B.V. All rights reserved.