Multifunctional scanning ion conductance microscopy

Abstract

Scanning ion conductance microscopy (SICM) is a nanopipette-based technique that has traditionally been used to image topography or to deliver species to an interface, particularly in a biological setting. This article highlights the recent blossoming of SICM into a technique with a much greater diversity of applications and capability that can be used either standalone, with advanced control (potential-time) functions, or in tandem with other methods. SICM can be used to elucidate functional information about interfaces, such as surface charge density or electrochemical activity (ion fluxes). Using a multi-barrel probe format, SICM-related techniques can be employed to deposit nanoscale three-dimensional structures and further functionality is realized when SICM is combined with scanning electrochemical microscopy (SECM), with simultaneous measurements from a single probe opening up considerable prospects for multifunctional imaging. SICM studies are greatly enhanced by finite-element method modelling for quantitative treatment of issues such as resolution, surface charge and (tip) geometry effects. SICM is particularly applicable to the study of living systems, notably single cells, although applications extend to materials characterization and to new methods of printing and nanofabrication. A more thorough understanding of the electrochemical principles and properties of SICM provides a foundation for significant applications of SICM in electrochemistry and interfacial science.

Extracellular Surface Potential Mapping by Scanning Ion Conductance Microscopy Revealed Transient Transmembrane Pore Formation Induced by Conjugated Polymer Nanoparticles

“…[33] In recent years, there have been exciting developments to make SICM a multifunctional microscope. [34][35][36] SICM regulates the tip-sample distance based on the ionic current through the nanoscale opening at the tip of the nanopipette probe, which is highly sensitive to the local electrical properties, including surface charge, potential, and ion flux. Therefore, SICM techniques have been extended to map the electrical and electrochemical properties of a surface, along with topography imaging.…”

“…However, both the electrode‐based techniques, such as patch‐clamp or multielectrode arrays (MEAs) methods, and the emerging voltage‐sensitive fluorescence imaging techniques cannot provide necessary spatial resolution and long‐term stability to probe local extracellular potential changes of nano–bio interactions . In recent years, there have been exciting developments to make SICM a multifunctional microscope . SICM regulates the tip‐sample distance based on the ionic current through the nanoscale opening at the tip of the nanopipette probe, which is highly sensitive to the local electrical properties, including surface charge, potential, and ion flux.…”

Differential-Concentration Scanning Ion Conductance Microscopy

“…In the case of conventional SICM, at the lower surface charge densities applied to the substrate, EOF has very little effect on calculated ionic currents, in line with previously reported studies. 10,22,35 However, as the surface charge increases beyond about -30 mC/m 2 , EOF can be seen to be an important consideration.…”

Development of high-speed ion conductance microscopy

“…Moreover, the SICM nanopipette has recently been used to measure surface charge density [15][16][17][18][19][20][21] and electrochemical activity [22,23] as well as to deliver species [24][25][26][27]. Thus, SICM is now becoming a useful tool in biological studies, especially for characterizing single cells with very soft and fragile surfaces [28].…”