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Title: Microrheology of human lung epithelial cells measured by atomic force microscopy
Author: Alcaraz Casademunt, Jordi
Buscemi Estefanell, Lara
Grabulosa Descals, Mireia
Trepat Guixer, Xavier
Fabry, Ben
Farré Ventura, Ramon
Navajas Navarro, Daniel
Keywords: Microscòpia de força atòmica
Membrana mucosa
Reologia (Biologia)
Atomic force microscopy
Mucous membrane
Rheology (Biology)
Issue Date: 2003
Publisher: Biophysical Society
Abstract: Lung epithelial cells are subjected to large cyclic forces from breathing. However, their response to dynamic stresses is poorly defined. We measured the complex shear modulus (G*(ω)) of human alveolar (A549) and bronchial (BEAS-2B) epithelial cells over three frequency decades (0.1–100 Hz) and at different loading forces (0.1–0.9 nN) with atomic force microscopy. G*(ω) was computed by correcting force-indentation oscillatory data for the tip-cell contact geometry and for the hydrodynamic viscous drag. Both cell types displayed similar viscoelastic properties. The storage modulus G′(ω) increased with frequency following a power law with exponent ∼0.2. The loss modulus G″(ω) was ∼2/3 lower and increased similarly to G′(ω) up to ∼10 Hz, but exhibited a steeper rise at higher frequencies. The cells showed a weak force dependence of G′(ω) and G″(ω). G*(ω) conformed to the power-law model with a structural damping coefficient of ∼0.3, indicating a coupling of elastic and dissipative processes within the cell. Power-law behavior implies a continuum distribution of stress relaxation time constants. This complex dynamics is consistent with the rheology of soft glassy materials close to a glass transition, thereby suggesting that structural disorder and metastability may be fundamental features of cell architecture.
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It is part of: Biophysical Journal, 2003, vol. 84, num. 3, p. 2071-2079
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ISSN: 0006-3495
Appears in Collections:Articles publicats en revistes (Ciències Fisiològiques)

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