Bio-Mimicking, Electrical Excitability Phenomena Associated With Synthetic Macromolecular Systems: A Brief Review With Connections to the Cytoskeleton and Membraneless Organelles

Susan K. Kozawa,Alberto C. S. Costa,Gary E. Wnek

doi:10.3389/fnmol.2022.830892

Susan K. Kozawa, Alberto C. S. Costa + Show 1 more

Open Access

https://doi.org/10.3389/fnmol.2022.830892

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Abstract

Electrical excitability of cells, tissues and organs is a fundamental phenomenon in biology and physiology. Signatures of excitability include transient currents resulting from a constant or varying voltage gradient across compartments. Interestingly, such signatures can be observed with non-biologically-derived, macromolecular systems. Initial key literature, dating to roughly the late 1960’s into the early 1990’s, is reviewed here. We suggest that excitability in response to electrical stimulation is a material phenomenon that is exploited by living organisms, but that is not exclusive to living systems. Furthermore, given the ubiquity of biological hydrogels, we also speculate that excitability in protocells of primordial organisms might have shared some of the same molecular mechanisms seen in non-biological macromolecular systems, and that vestigial traces of such mechanisms may still play important roles in modern organisms’ biological hydrogels. Finally, we also speculate that bio-mimicking excitability of synthetic macromolecular systems might have practical biomedical applications.

Highlights

“An attempt to decide what constitutes the difference between living matter and dead matter cannot avoid the observation that one especial characteristic of living matter is its power to react to changes in its environment. . .This responsiveness is sometimes called the irritability of living matter, though the term excitability is preferable.” opens Mitchell’s textbook on General Physiology (Mitchell, 1948)
Less well-known are examples of synthetic macromolecular systems that under certain conditions exhibit electrical signatures reminiscent of those typically recorded from excitable cells, Electrical Excitability Phenomena such as current transients in response to applied voltage gradients
We speculate on the possibility that electrical excitability and signaling through biological hydrogels may have played key roles in protocells of primordial organisms, some of which might still be of functional importance in modern organisms

Summary

Introduction

“An attempt to decide what constitutes the difference between living matter and dead matter cannot avoid the observation that one especial characteristic of living matter is its power to react to changes in its environment. . .This responsiveness is sometimes called the irritability of living matter, though the term excitability is preferable.” opens Mitchell’s textbook on General Physiology (Mitchell, 1948). It has been known for many decades that application of a voltage gradient across, for example, a cell membrane by voltageclamping leads to rapid current transients through a variety of ion channels (Hille, 2001).

Results

Conclusion