Page, Ashley M., Perry, David, Young, Philip J., Mitchell, Daniel A., Frenguelli, Bruno G. and Unwin, Patrick R. (2016) Fast nanoscale surface charge mapping with pulsed-potential scanning ion conductance microscopy. Analytical Chemistry, 88 (22). pp. 10854-10859. doi:10.1021/acs.analchem.6b03744

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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.

Item Type:	Journal Article
Subjects:	Q Science > QD Chemistry T Technology > TP Chemical technology
Divisions:	Faculty of Science > Chemistry
Library of Congress Subject Headings (LCSH):	Surface chemistry, Nanochemistry, Scanning probe microscopy, Atomic force microscopy
Journal or Publication Title:	Analytical Chemistry
Publisher:	American Chemical Society
ISSN:	0003-2700
Official Date:	24 October 2016
Dates:	Date Event 24 October 2016 Published 24 October 2016 Accepted 22 September 2016 Submitted
Volume:	88
Number:	22
Page Range:	pp. 10854-10859
DOI:	10.1021/acs.analchem.6b03744
Status:	Peer Reviewed
Publication Status:	Published
Access rights to Published version:	Restricted or Subscription Access
Funder:	Engineering and Physical Sciences Research Council (EPSRC), University of Warwick. Molecular Organisation and Assembly in Cells
Grant number:	EP/F500378/1, (EPSRC)

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