skip to main content
US FlagAn official website of the United States government
dot gov icon
Official websites use .gov
A .gov website belongs to an official government organization in the United States.
https lock icon
Secure .gov websites use HTTPS
A lock ( lock ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Explore Research Products in the PAR
It may take a few hours for recently added research products to appear in PAR search results.


Title: Physical limits on galvanotaxis
Eukaryotic cells can polarize and migrate in response to electric fields via “galvanotaxis,” which aids wound healing. Experimental evidence suggests cells sense electric fields via molecules on the cell's surface redistributing via electrophoresis and electroosmosis, though the sensing species has not yet been conclusively identified. We develop a model that links sensor redistribution and galvanotaxis using maximum likelihood estimation. Our model predicts a single universal curve for how galvanotactic directionality depends on field strength. We can collapse measurements of galvanotaxis in keratocytes, neural crest cells, and granulocytes to this curve, suggesting that stochasticity due to the finite number of sensors may limit galvanotactic accuracy. We find cells can achieve experimentally observed directionalities with either a few (~100) highly polarized sensors or many (~10,000) sensors with an ∼6–10% change in concentration across the cell. We also identify additional signatures of galvanotaxis via sensor redistribution, including the presence of a tradeoff between accuracy and variance in cells being controlled by rapidly switching fields. Our approach shows how the physics of noise at the molecular scale can limit cell-scale galvanotaxis, providing important constraints on sensor properties and allowing for new tests to determine the specific molecules underlying galvanotaxis.  more » « less
Award ID(s):
2119948 1915491
PAR ID:
10513797
Author(s) / Creator(s):
; ;
Publisher / Repository:
American Physical Society
Date Published:
Journal Name:
Physical Review E
Volume:
108
Issue:
6
ISSN:
2470-0045
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
More Like this
  1. ; (, PLOS One)
    Sung, Baeckkyoung (Ed.)
    Collective response to external directional cues like electric fields helps guide tissue development, regeneration, and wound healing. In this study we focus on the impact of anisotropy in cell shape and local cell alignment on the collective response to electric fields. We model elongated cells that have a different accuracy sensing the field depending on their orientation with respect to the field. With this framework, we assume cells are better sensors if they can align their long axes perpendicular to the field. Elongated cells often line up with their long axes in the same direction — “nematic order” – does a nematic cell-cell interaction allow groups of cells to share information about their orientation to sense fields more accurately? We use simulations of a simple model to show that if cells orient themselves perpendicular to their average velocity, alignment of a cell’s long axis to its nearest neighbors’ orientation can in some circumstances enhance the directional response to electric fields. We also show that cell-cell adhesion modulates the accuracy of cells in the group. 
    more » « less
  2. ; ; ; (, Biotechnology and Bioengineering)
    Abstract Magnetoelastic (ME) sensors, which can be remotely activated via magnetic fields, are an excellent choice for wireless monitoring of biological parameters due to their ability to be scaled into different sizes and have their surface functionalized for chemical or biological sensing. In this study, we present the application of a commercially available ME material (Metglas 2826 MB) to develop a sensor system that can monitor the attachment of anchorage‐dependent mammalian cells in two‐dimensional in vitro cell cultures. Results obtained with the developed sensors and detection system correlated with microscopic image analysis of cell quantification, which showed a linear relationship between the sensor response and attached fibroblast cells on the sensor surface. It was also revealed that the developed ME sensor system is capable of providing temporal profiles of cell growth corresponding to different stages of cell attachment and proliferation in real‐time. 
    more » « less
  3. ; (, Proceedings of the National Academy of Sciences)
    Interaction of electric fields with biological cells is indispensable for many physiological processes. Thermal electrical noise in the cellular environment has long been considered as the minimum threshold for detection of electrical signals by cells. However, there is compelling experimental evidence that the minimum electric field sensed by certain cells and organisms is many orders of magnitude weaker than the thermal electrical noise limit estimated purely under equilibrium considerations. We resolve this discrepancy by proposing a nonequilibrium statistical mechanics model for active electromechanical membranes and hypothesize the role of activity in modulating the minimum electrical field that can be detected by a biological membrane. Active membranes contain proteins that use external energy sources to carry out specific functions and drive the membrane away from equilibrium. The central idea behind our model is that active mechanisms, attributed to different sources, endow the membrane with the ability to sense and respond to electric fields that are deemed undetectable based on equilibrium statistical mechanics. Our model for active membranes is capable of reproducing different experimental data available in the literature by varying the activity. Elucidating how active matter can modulate the sensitivity of cells to electric signals can open avenues for a deeper understanding of physiological and pathological processes. 
    more » « less
  4. ; ; ; ; ; ; (, Transducers 2019)
    Microfluidic devices integrated with Coulter sensors have been widely used in counting and characterizing suspended particles. The electrodes in these devices are mostly arranged in a coplanar fashion due to a simple fabrication process and leads to non-uniform electric fields confined to the floor of the microfluidic channel. We have recently introduced a simple fabrication method that can effortlessly create parallel electrodes in microfluidic devices built with soft-lithography. In this paper, we theoretically and experimentally analyze the developed parallel-electrode Coulter sensor and compare its sensitivity with that of the Coulter sensor built on conventional coplanar electrodes. Both our simulation results and experiments with cell suspensions show that parallel-electrode Coulter sensor can provide as much as ~5× sensitivity improvement over conventional coplanar electrodes. 
    more » « less
  5. ; ; ; ; ; ; ; (, ECS Sensors Plus)
    Wearable stretch sensors have potential applications across many fields including medicine and sports, but the accuracy of the data produced by the sensors over repeated uses is largely unknown due to a paucity of high-cycle fatigue (HCF) studies on both the materials comprising the sensors and the signal produced by the sensors. To overcome these limitations, using human physiologically-based parameters, stretch sensors were subjected to quasi-static testing and HCF with simultaneous capture of the signal. The strain produced by the sensor was then compared to the strain produced by testing instrument, and the results suggest that the output from the stretch sensors is strongly correlated with output from the testing instrument under quasi-static conditions; however, this correlation deteriorates under fatigue conditions. Such deterioration may be the result of several factors, including a mismatch between the material response to fatiguing and the signal response to fatiguing. From a materials perspective, the shape of the stress-life curve for the polymers comprising the sensors conforms to the Rabinowitz-Beardmore model of polymer fatigue. Based on these results, consideration of the material properties of a stretch sensor are necessary to determine how accurate the output from the sensor will be for a given application. 
    more » « less
  • Citation Formats
  • MLA
  • APA
  • Chicago
  • BibTeX
  • Save / Share this Record
  • Send to Email