Scanning ion conductance microscopy (SICM) is a versatile technique of scanning probe microscopy (SPM) family, which is especially useful in biological and electrophysiological studies. SICM utilizes an electrolyte-filled nanopipette to image topography and obtain local ion currents of sample surfaces with high spatial resolution. One important application of SICM is to study ion transport in various systems including cell membranes. With the ability of measuring ion currents with nanoscale spatial resolution, SICM provides a good tool to measure nanoscale transport properties. Our group has focused on using SICM to study transport through nanopores and across cell junctions, and has modified SICM into different configurations to achieve precise control of transmembrane potential and more sensitive measurements. First, in original two-electrode SICM, local conductance variance can be studied with applying a concentration gradient across a porous membrane. Then three or four-electrode configuration was developed, allowing precise control of transmembrane potentials. By using a dual-barrel nanopipette, we are able to add a �potential probe�, which measures the potential change occurs in the vicinity of the probe. Potential measurement is more sensitive than current measurement; therefore, it allows SICM to operate under the electrolyte concentrations and potentials that are more suitable to biological systems, for example, cell monolayers. In SICM, probe position could be accurately controlled, thus we are able to study the transport across cell junction. Here, the developments of SICM instrumentation from two- to five-electrode and associated applications are shown.

Development of scanning ion conductance microscopy

246th National Meeting (2013)

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