Linearity and time-scale invariance of the creep function in living cells.
We report here the creep function measured in three cell types, after a variety of interventions, and over three time decades (from 3 ms to 3.2 s). In each case the response conformed to a power law, implying that no distinct molecular relaxation times or time constants could characterize the response. These results add to a growing body of evidence that stands in contrast to widely used viscoelastic models featuring at most a few time constants. We show instead that the ability of the matrix to deform is time-scale invariant and characterized by only one parameter: the power law exponent that controls the transition between solid-like and liquid-like behaviour. Moreover, we validate linearity by comparison of measurements in the time and frequency domains.
Lenormand
G
G
Physiology Program, School of Public Health, Harvard University, 665 Huntington Avenue, Boston, MA 02115, USA. glenorma@hsph.harvard.edu
Millet
E
E
Fabry
B
B
Butler
J P
JP
Fredberg
J J
JJ
D002465:Cell Movement / Q000502:physiology*; D048429:Cell Size; D002478:Cells, Cultured; D003198:Computer Simulation; D004548:Elasticity; D006801:Humans; D007700:Kinetics; D016014:Linear Models; D008954:Models, Biological; D032389:Myocytes, Smooth Muscle / Q000166:cytology* / Q000502:physiology*; D013314:Stress, Mechanical; D013997:Time Factors; D014783:Viscosity