Fabrication and Characterization of Dual Function Nanoscale pH-Scanning Ion Conductance Microscopy (SICM) Probes for High Resolution pH Mapping

Abstract

(2013) Fabrication and characterization of dual function nanoscale pH-scanning ion conductance microscopy (SICM) probes for high resolution pH mapping. Analytical Chemistry, Volume 85 (Number 17). pp. 8070-8074 Permanent WRAP url: http://wrap.warwick.ac.uk/57249 Copyright and reuse:The Warwick Research Archive Portal (WRAP) makes this work of researchers of the University of Warwick available open access under the following conditions. Copyright © and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable the material made available in WRAP has been checked for eligibility before being made available.Copies of full items can be used for personal research or study, educational, or not-forprofit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. Publisher's statement:This document is the Accepted Manuscript version of a Published Work that appeared in final form in Analytical Chemistry copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work http://dx.doi.org/10.1021/ac401883n The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP url' above for details on accessing the published version and note that access may require a subscription. AbstractThe easy fabrication and use of nanoscale dual function pH-scanning ion conductance microscopy (SICM) probes is reported. These probes incorporate an iridium oxide coated carbon electrode for pH measurement and an SICM barrel for distance control, enabling simultaneous pH and topography mapping. These pH-SICM probes were fabricated rapidly from laser pulled theta quartz pipets, with the pH electrode prepared by in-situ carbon filling of one of the barrels by the pyrolytic decomposition of butane, followed by electrodeposition of a thin layer of hydrous iridium oxide. The other barrel was filled with an electrolyte solution and Ag/AgCl electrode as part of a conductance cell for SICM. The fabricated probes, with pH and SICM sensing elements typically on the 100 nm scale, were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy and various electrochemical measurements. They showed a linear super-Nernstian pH response over a range of pH (pH 2-10). The capability of the pH-SICM probe was demonstrated by detecting both pH and topographical changes during the dissolution of a calcite microcrystal in aqueous solution. This system illustrates the quantitative nature of pH-SICM imaging, because the dissolution process changes the crystal height and interfacial pH (compared to bulk) and each is sensitive to the rate. Both measurements reve...

Characterization of Nanopipettes

“…2,3 While the simplest nanopipettes contain just a single channel, multichannel devices are also possible, which increases the versatility of nanopipettes for nanoscience applications. 4,5 The channels can be open 5,6 (filled with electrolyte and a control electrode) or functionalized with deposited carbon, for example, to produce ultramicroelectrodes (UMEs) 7,8 that can also be further functionalized [9][10][11] to tune the sensory properties. Nanoelectrodes can also be fabricated by electrochemically plating nanopipettes with a variety of different metals.…”

Quad-Barrel Multifunctional Electrochemical and Ion Conductance Probe for Voltammetric Analysis and Imaging

“…were filled with carbon to form the electrodes by adapting a carbon electrode fabrication process described previously. [29][30][31] Briefly, the top ends of two diagonally opposite barrels were closed by using 'Blu-Tack' (Bostik, UK) and butane was passed through the other two barrels, via tubing, with the end held under an argon atmosphere. The tip of the pipet was heated with a butane torch, for 35 s, to deposit carbon pyrolytically from the butane, thus forming the electrodes, as illustrated in Figure 1A.…”

Multifunctional scanning ion conductance microscopy

“…This allowed precise subcellular measurements of molecular uptake rates and the protocol was particularly important to avoid complications from substantial drift (deterioration) of the SECM response. SECM-SICM has also been employed for pH sensing [140,142], allowing the acquisition of simultaneous topography-potentiometric pH maps of surfaces. Functionalization of a carbon electrode in the SECM-SICM set-up with platinum has also permitted measurements of O 2 [143,144] and H 2 O 2 [145] by amperometry.…”