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Biological supramolecular assemblies, such as phospholipid bilayer membranes, have been used to demonstrate signal processing via short-term synaptic plasticity (STP) in the form of paired pulse facilitation and depression, emulating the brain’s efficiency and flexible cognitive capabilities. However, STP memory in lipid bilayers is volatile and cannot be stored or accessed over relevant periods of time, a key requirement for learning. Using droplet interface bilayers (DIBs) composed of lipids, water and hexadecane, and an electrical stimulation training protocol featuring repetitive sinusoidal voltage cycling, we show that DIBs displaying memcapacitive properties can also exhibit persistent synaptic plasticity in the form of long-term potentiation (LTP) associated with capacitive energy storage in the phospholipid bilayer. The time scales for the physical changes associated with the LTP range between minutes and hours, and are substantially longer than previous STP studies, where stored energy dissipated after only a few seconds. STP behavior is the result of reversible changes in bilayer area and thickness. On the other hand, LTP is the result of additional molecular and structural changes to the zwitterionic lipid headgroups and the dielectric properties of the lipid bilayer that result from the buildup of an increasingly asymmetric charge distribution at the bilayer interfaces.
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Investigation of the Electrical properties of Phosphatidylserine Lipid Bilayer Membranes
In this work we investigate the electrical properties of phospholipid bilayer membranes (LBMs) formed from phosphatidylserine by analyzing two experimental setups. The Electrochemical Impedance Spectra (EIS) of phosphatidylserine show that a lipid bilayer membrane formed from this phospholipid has an average specific electrical resistance of 3.466 k Ω.cm 2 and an average capacitance of 0.385 µF/cm 2 . Some of the major factors that affect the LBM resistance include electroporation, the method of deposition, and the surface tension in microchannels for supported LBMs. Therefore, wide apertures remain the most accurate method for supporting LBMs.
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- Award ID(s):
- 2000685
- PAR ID:
- 10331754
- Date Published:
- Journal Name:
- Proceeding of the 2022 IEEE Southeast Conference
- Page Range / eLocation ID:
- 706 to 710
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1109/SoutheastCon48659.2022.9764102
