title: Fast Nanoscale Surface Charge Mapping with Pulsed-Potential Scanning Ion Conductance Microscopy.
abstract: A vast range of interfacial systems exhibit charge heterogeneities on the nanoscale. These differences in local surface charge density are challenging to visualize, but recent work has shown the scanning ion conductance microscope (SICM) to be a very promising tool to spatially resolve and map surface charge and topography via a hopping potential sweep technique with a single nanopipette probe, with harmonic modulation of a bias applied between quasi-reference counter electrodes in the nanopipette and bulk solution, coupled with lock-in detection. Although powerful, this is a relatively slow process, with limitations on resolution and the size of the images that can be collected. Herein, we demonstrate a new scanning routine for mapping surface charge and topography with SICM, which increases the data acquisition rate by an order of magnitude and with the potential for further gains. Furthermore, the method is simplified, eliminating the need for bias modulation lock-in detection, by utilizing a potential-pulse, chronoamperometric approach, with self-referencing calibration of the response at each pixel in the image. We demonstrate the application of this new method to both a model substrate and living PC-12 cells under physiological (high ionic strength) conditions, where charge mapping is most challenging (small Debye length). This work contributes significantly to the emergence of SICM as a multifunctional technique for simultaneously probing interfacial structure and function with nanometer resolution.
authors: Department of Chemistry, ‡MOAC Doctoral Training Centre, §School of Life Sciences, and ∥Warwick Medical School, University of Warwick , Coventry, CV4 7AL, United Kingdom.
authors: Ashley
authors: A
authors: Page
authors: Department of Chemistry, ‡MOAC Doctoral Training Centre, §School of Life Sciences, and ∥Warwick Medical School, University of Warwick , Coventry, CV4 7AL, United Kingdom.
authors: David
authors: D
authors: Perry
authors: Department of Chemistry, ‡MOAC Doctoral Training Centre, §School of Life Sciences, and ∥Warwick Medical School, University of Warwick , Coventry, CV4 7AL, United Kingdom.
authors: Philip
authors: P
authors: Young
authors: Department of Chemistry, ‡MOAC Doctoral Training Centre, §School of Life Sciences, and ∥Warwick Medical School, University of Warwick , Coventry, CV4 7AL, United Kingdom.
authors: Daniel
authors: D
authors: Mitchell
authors: Department of Chemistry, ‡MOAC Doctoral Training Centre, §School of Life Sciences, and ∥Warwick Medical School, University of Warwick , Coventry, CV4 7AL, United Kingdom.
authors: Bruno G
authors: BG
authors: Frenguelli
authors: Department of Chemistry, ‡MOAC Doctoral Training Centre, §School of Life Sciences, and ∥Warwick Medical School, University of Warwick , Coventry, CV4 7AL, United Kingdom.
authors: Patrick R
authors: PR
authors: Unwin