Regensburg 2007 – scientific programme
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BP: Fachverband Biologische Physik
BP 8: Charge Transfer
BP 8.1: Talk
Monday, March 26, 2007, 18:00–18:15, H44
Three-dimensional conductance mapping on living cells with scanning ion conductance microscopy — •Matthias Böcker1,2, Joachim Wegener3, and Tilman Schäffer1,2 — 1Center for Nanotechnology (CeNTech), Heisenbergstr. 11, 48149 Münster — 2Physikalisches Institut, Wilhelm-Klemm-Str. 10, 48149 Münster — 3Institut für Biochemie, Wilhelm-Klemm-Str. 2, 48149 Münster
A scanning ion conductance microscope (SICM) is based on an electrolyte-filled, tapered micropipette that acts as nanoscale current probe while being scanned over a sample surface. We used SICM to study the ion permeability of tissue-like cell layers with lateral resolution. For MDCK-II cells, we measured a larger ion conductance along the cell periphery in areas of cell-cell contacts, compared to that along the cell bodies. This suggests that ions mainly pass through the paracellular cleft between adjacent cells but not through the cellular plasma membrane.
In order to further refine these measurements, we implemented a novel three-dimensional imaging mode. In this mode, the micropipette is scanned in all three spatial dimensions over the sample surface while recording the ion conductance. The sample surface topography is tracked by using a complementary shear-force distance control with an optical readout. This allows us to create maps of ion conductance not only in a plane, but in a volume directly above the sample surface, revealing refined aspects of conductive sample properties.