06 Jan

Single Molecule Biophysics: 2013

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Professor Talaga is presenting "Electrochemical impedance spectroscopy of nanopores" at the Single Molecule Biophysics Conference at the Aspen Center for Physics. 

Abstract: Nanopores have found increasing numbers of applications in basic science research and biotechnological devices. The favorable physical and chemical properties of solid state nanopores makes them attractive for many of these applications. However, the geometry and surface properties of such nanopores is often variable and must be characterized for each experiment. Such characterization typically takes place before or after the experiment. We have developed an approach to characterize the geometry and surface characteristics of nanopores using electrochemical impedance spectroscopy (EIS). We show how EIS can be used to determine the geometry and surface charge density of nanopores and apply the approach to nanocapillaries, focussed ion beam drilled nanopores (~90 nm), and noble gas ion beam sculpted nanopores (~20 nm). The ladder differential equation developed to allow inversion of the EIS to geometry is further adapted to treat the presence of an unfolded protein in the nanopore. We show how the EIS spectrum is expected to shift in response to the local coarse-grain sequence of the unfolded polypeptide chain. The results show that the EIS spectrum is substantially more sensitive to nanopore geometry and local sequence information than traditional DC resistive pulse measurements.

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