Power-Law Stress and Creep Relaxations of Single Cells Measured by Colloidal Probe Atomic Force Microscopy

Abstract

We measured stress and creep relaxations of mouse fibroblast cells arranged and cultured on a microarray, by colloidal probe atomic force microscopy (AFM) .

Application of the Johnson–Kendall–Roberts model in AFM-based mechanical measurements on cells and gel.

“…The above results show that presence of proteins in the medium also affects probe-cell adhesion, which may be connected with endocytosis-associated or receptor-ligand binding events on the cell surface. It was shown that probe hydrophobization can decrease adhesion to the cell surface [9], but not completely, and this effect can be cell specific [59]. Overall, cell adhesion is a very specific matter and can be affected by cell type, probe material, medium composition and other parameters.…”

“…6C). Indeed, for the PAA gels, force relaxation can be roughly described by single exponential decay in accordance with the standard linear solid model [41], while for cells the power law decay model is more appropriate [9,42,43]. The associated increase in the indentation depth and contact area due to the decrease in cantilever deflection achieved ≈6%, which may contribute to the increase in F ad .…”

“…The obtained dependencies are called force versus distance curves (force curves, FCs). The colloidal probes, which consist of a spherical colloidal particle of few micrometers in diameter attached to an AFM cantilever, provide accurate control of the probe geometry [5,[7][8][9]. Commonly the Hertz model or its modifications is applied to the approach (loading, extension) part of FCs to extract Young's modulus (E), the elastic parameter used for the characterization of the sample's mechanical properties.…”

Mapping power-law rheology of living cells using multi-frequency force modulation atomic force microscopy

“…Rheological properties of single cells have been investigated in the time domain with creep 23,24 and stress relaxation [25][26][27] experiments. Those techniques were used recently to map the relaxation behavior of single cells.…”

“…This suffers from the precise estimate of the Newtonian viscous damping coefficient l in the power-law rheology. 17 Also, to optimize the mapping time, a longer relaxation process exhibiting a power-law behavior 24 is difficult to be measured. 28,29 Those limits mentioned above are not imposed on frequency domain measurements.…”