posted on 2024-03-18, 17:38authored byEssraa
A. Hussein, Brittany Rice, Ryan J. White
Ion channel probes, as one of the ion channel platforms,
provide
an appealing opportunity to perform localized detection with a high
precision level. These probes come basically in two classes: glass
and metal. While the glass-based probes showed the potential to be
employed for molecular sensing and chemical imaging, these probes
still suffer from limited resolution and lack of control over protein
insertion. On the other hand, metal-based nanoneedle probes (gold
and silver) have been recently developed to allow reducing probe dimensions
to the nanoscale geometry. More specifically, silver probes are preferable
owing to their ability to mitigate the channel current decay observed
with gold probes and provide a stable DC channel current. However,
there are still some challenges related to the probe design and bilayer
curvature that render such probes insensitive to small changes in
the tip–substrate distance. Herein, we introduce two main pathways
to control the probe–bilayer architecture; the first is by
altering the probe shape and geometry during the fabrication process
of silver probes. The second pathway is by altering the surface characteristics
of the silver probe via an electrophoretic deposition process. Our
findings reveal that varying the electrochemical etching parameters
results in different probe geometries and producing sharper tips with
a 2-fold diameter reduction. In addition, the electrophoretic deposition
of a cathodic paint on the silver nanoneedle surface led to a miniaturized
exposed silver tip that enables the formation of a confined bilayer.
We further investigated the characteristics of bilayers supported
on both the sharper nanoneedles and the HSR-coated silver probes produced
by controlling the etching conditions and electrodeposition process,
respectively. We believe this work paves the way to rationally design
silver nanoneedle ion channel probes, which are well suited for localized
molecular sensing and chemical imaging.