Pitfalls and Experimental Issues in Measuring Ion Flux from Actuating Conducting Polymers Using Scanning Ion Conductance Microscopy

2011 ◽  
Vol 700 ◽  
pp. 129-132 ◽  
Author(s):  
Cosmin Laslau ◽  
David E. Williams ◽  
Bryon E. Wright ◽  
Jadranka Travas Sejdic
Keyword(s):  
Conducting Polymers ◽  
Operating Mode ◽  
Separation Distance ◽  
Ion Flux ◽  
Ion Conductance ◽  
Scanning Ion Conductance Microscopy ◽  
Out Of Plane ◽  
Flux Measurements ◽  
Film Substrate ◽  
Spatially Varying

We discuss experimental issues associated with a novel operating mode of scanning ion conductance microscopy (SICM). This mode characterizes the ion fluxes that emanate from conducting polymers (CPs) as they actuate, important for understanding CP applications ranging from artificial muscles to micropumps. The CP studied is a thin film of poly (3,4-ethylenedioxythiophene) (PEDOT) actuated out of plane. We outline the design principles underpinning our CP ion flux measurements and discuss experimental complications that arose - most notably a baseline current that may be attributable to a spatially varying CP oxidation state. We discuss the dependence of this baseline ion flux current on the separation distance between SICM tip and CP film, substrate type and substrate area.

scholarly journals Cell stiffness and ROS level alterations in living neurons mediated by β-amyloid oligomers measured by scanning ion-conductance microscopy.

2021 ◽  
Vol 27 (S1) ◽  
pp. 500-502
Author(s):  
Oleg Suchalko ◽  
Roman Timoshenko ◽  
Alexander Vaneev ◽  
Vasilii Kolmogorov ◽  
Nikita Savin ◽  
...  
Keyword(s):  
Cell Stiffness ◽  
Ion Conductance ◽  
Scanning Ion Conductance Microscopy ◽  
Amyloid Oligomers ◽  
Β Amyloid ◽  
Living Neurons

scholarly journals Azimuthal Anchoring Strength in Photopatterned Alignment of a Nematic

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 675
Author(s):  
H. Nilanthi Padmini ◽  
Mojtaba Rajabi ◽  
Sergij V. Shiyanovskii ◽  
Oleg D. Lavrentovich
Keyword(s):  
Liquid Crystal ◽  
Point Defects ◽  
Elastic Energy ◽  
Separation Distance ◽  
Thin Layers ◽  
Uv Exposure ◽  
Surface Anchoring ◽  
Anchoring Strength ◽  
Spatially Varying

Spatially-varying director fields have become an important part of research and development in liquid crystals. Characterization of the anchoring strength associated with a spatially-varying director is difficult, since the methods developed for a uniform alignment are seldom applicable. Here we characterize the strength of azimuthal surface anchoring produced by the photoalignment technique based on plasmonic metamsaks. The measurements used photopatterned arrays of topological point defects of strength +1 and −1 in thin layers of a nematic liquid crystal. The integer-strength defects split into pairs of half-integer defects with lower elastic energy. The separation distance between the split pair is limited by the azimuthal surface anchoring, which allows one to determine the strength of the latter. The strength of the azimuthal anchoring is proportional to the UV exposure time during the photoalignment of the azobenzene layer.

scholarly journals Nanoscale Cell Membrane Fluctuations Measured by Scanning Ion Conductance Microscopy

2013 ◽  
Vol 104 (2) ◽  
pp. 317a
Author(s):  
Yusuke Mizutani ◽  
Zen Ishikura ◽  
Myung-Hoon Choi ◽  
Sang-Joon Cho ◽  
Takaharu Okajima
Keyword(s):  
Cell Membrane ◽  
Ion Conductance ◽  
Scanning Ion Conductance Microscopy ◽  
Membrane Fluctuations

scholarly journals Kv1.1 channelopathy abolishes presynaptic spike width modulation by subthreshold somatic depolarization

2017 ◽  
Vol 114 (9) ◽  
pp. 2395-2400 ◽  
Author(s):  
Umesh Vivekananda ◽  
Pavel Novak ◽  
Oscar D. Bello ◽  
Yuri E. Korchev ◽  
Shyam S. Krishnakumar ◽  
...  
Keyword(s):  
Potassium Channels ◽  
Calcium Influx ◽  
Digital Transmission ◽  
Ion Conductance ◽  
Scanning Ion Conductance Microscopy ◽  
Spike Shape ◽  
Presynaptic Spike ◽  
Synaptic Boutons ◽  
Episodic Ataxia Type

Although action potentials propagate along axons in an all-or-none manner, subthreshold membrane potential fluctuations at the soma affect neurotransmitter release from synaptic boutons. An important mechanism underlying analog–digital modulation is depolarization-mediated inactivation of presynaptic Kv1-family potassium channels, leading to action potential broadening and increased calcium influx. Previous studies have relied heavily on recordings from blebs formed after axon transection, which may exaggerate the passive propagation of somatic depolarization. We recorded instead from small boutons supplied by intact axons identified with scanning ion conductance microscopy in primary hippocampal cultures and asked how distinct potassium channels interact in determining the basal spike width and its modulation by subthreshold somatic depolarization. Pharmacological or genetic deletion of Kv1.1 broadened presynaptic spikes without preventing further prolongation by brief depolarizing somatic prepulses. A heterozygous mouse model of episodic ataxia type 1 harboring a dominant Kv1.1 mutation had a similar broadening effect on basal spike shape as deletion of Kv1.1; however, spike modulation by somatic prepulses was abolished. These results argue that the Kv1.1 subunit is not necessary for subthreshold modulation of spike width. However, a disease-associated mutant subunit prevents the interplay of analog and digital transmission, possibly by disrupting the normal stoichiometry of presynaptic potassium channels.

Scanning Ion Conductance Microscopy for High-Resolution Topography of Soft Samples Including Live Cells

2011 ◽  
Vol 17 (S2) ◽  
pp. 236-237
Author(s):  
G De Filippi ◽  
C Moore
Keyword(s):  
High Resolution ◽  
Live Cells ◽  
Ion Conductance ◽  
Scanning Ion Conductance Microscopy ◽  
Soft Samples

Extended abstract of a paper presented at Microscopy and Microanalysis 2011 in Nashville, Tennessee, USA, August 7–August 11, 2011.

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