an integrated field-effect microdevice for monitoring membrane transport in xenopus laevis oocytes via lateral proton diffusion一个集成的场效应微型装置监测膜运输在非洲爪蟾蜍光滑的卵母细胞通过横向质子扩散.pdfVIP

An Integrated Field-Effect Microdevice for Monitoring Membrane Transport in Xenopus laevis Oocytes via Lateral Proton Diffusion 1 2 3 3 2 Daniel Felix Schaffhauser , Monica Patti , Tatsuro Goda , Yuji Miyahara *, Ian Cameron Forster *, Petra Stephanie Dittrich3* 1 Department of Chemistry and Applied Biosciences, ETH Zurich, Zurich, Switzerland, 2 Institute for Physiology, University of Zurich, Zurich, Switzerland, 3 Institute of Biomaterials and Bioengineering, Tokyo Medical and Dental University, Tokyo, Japan Abstract An integrated microdevice for measuring proton-dependent membrane activity at the surface of Xenopus laevis oocytes is presented. By establishing a stable contact between the oocyte vitelline membrane and an ion-sensitive field-effect (ISFET) sensor inside a microperfusion channel, changes in surface pH that are hypothesized to result from facilitated proton lateral diffusion along the membrane were detected. The solute diffusion barrier created between the sensor and the active membrane area allowed detection of surface proton concentration free from interference of solutes in bulk solution. The proposed sensor mechanism was verified by heterologously expressing membrane transport proteins and recording changes in surface pH during application of the specific substrates. Experiments conducted on two families of phosphate- sodium cotransporters (SLC20 SLC34) demonstrated that it is possible to detect phosphate transport for both electrogenic and electroneutral isoforms and distinguish between transport of different phosphate species. Furthermore, the transport activity of the proton/amino acid cotransporter PAT1 assayed using conventional whole cell electrophysiology correlated