Stress relaxation of HepG2 cells measured by atomic force microscopy

Stress relaxation of HepG2 cells was examined with an atomic force microscope (AFM). In the measurement, a loading force was applied to the cell by an AFM tip, and a time series of the cantilever deflection signal was measured at a fixed position of the cantilever base displacement. The relaxation of the loading force was clearly observed on the HepG2 cells, and was well fitted to a stretched exponential function known as the Kohlrausch–Williams–Watts (KWW) function, which is empirically employed to represent dispersion processes of the system. The relaxation time and the stretching exponent parameter were estimated to be ~0.5 s and 0.4–0.6, respectively. The latter indicated that the relaxation observed in HepG2 cells consisted of multiple relaxation processes. Moreover, it was found that the characteristic feature of the relaxation process was not strongly correlated with the elastic properties of the cells.

[1]  I. N. Sneddon.  The relation between load and penetration in the axisymmetric boussinesq problem for a punch of arbitrary profile , 1965 .

[2]  V. Moy,et al.  Mechanical properties of L929 cells measured by atomic force microscopy: effects of anticytoskeletal drugs and membrane crosslinking. , 2006, Scanning.

[3]  S Lees,et al.  Measuring the microelastic properties of biological material. , 1992, Biophysical journal.

[4]  Ferenc Horkay,et al.  Determination of elastic moduli of thin layers of soft material using the atomic force microscope. , 2002, Biophysical journal.

[5]  M. Radmacher,et al.  From molecules to cells: imaging soft samples with the atomic force microscope. , 1992, Science.

[6]  Sandor Kasas,et al.  Deformation and height anomaly of soft surfaces studied with an AFM , 1993 .

[7]  J. Bechhoefer,et al.  Calibration of atomic‐force microscope tips , 1993 .

[8]  C. Rotsch,et al.  Dimensional and mechanical dynamics of active and stable edges in motile fibroblasts investigated by using atomic force microscopy. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[9]  Lee,et al.  Viscoelastic Responses of Polyhedral Oligosilsesquioxane Reinforced Epoxy Systems. , 1998, Macromolecules.

[10]  J. Alcaraz,et al.  Correction of Microrheological Measurements of Soft Samples with Atomic Force Microscopy for the Hydrodynamic Drag on the Cantilever , 2002 .

[11]  S. Hirotsu,et al.  Kinetics of volume phase transition in poly(N-isopropylacrylamide) gels , 2002 .

[12]  Peter Grütter,et al.  Probing the viscoelastic behavior of cultured airway smooth muscle cells with atomic force microscopy: stiffening induced by contractile agonist. , 2005, Biophysical journal.

[13]  Graham Williams,et al.  Non-symmetrical dielectric relaxation behaviour arising from a simple empirical decay function , 1970 .

[14]  Bhanu P. Jena,et al.  Atomic force microscopy in cell biology , 2002 .

[15]  H. Colten,et al.  Complement biosynthesis by the human hepatoma-derived cell line HepG2. , 1982, The Journal of clinical investigation.

[16]  F. Guilak,et al.  Viscoelastic properties of zonal articular chondrocytes measured by atomic force microscopy. , 2006, Osteoarthritis and cartilage.

[17]  A. P. Gunning,et al.  Atomic Force Microscopy for Biologists , 1999 .

[18]  K. Liao,et al.  Adhesion contact dynamics of HepG2 cells on galactose-immobilized substrates. , 2003, Biomaterials.

[19]  Dennis E Discher,et al.  Adhesively-tensed cell membranes: lysis kinetics and atomic force microscopy probing. , 2003, Biophysical journal.

[20]  P. Haydon,et al.  Actin filament dynamics in living glial cells imaged by atomic force microscopy. , 1992, Science.

[21]  D. Müller,et al.  Direct measurement of single-molecule visco-elasticity in atomic force microscope force-extension experiments , 2006, European Biophysics Journal.

[22]  F. MacKintosh,et al.  Scanning probe-based frequency-dependent microrheology of polymer gels and biological cells. , 2000, Physical review letters.

[23]  P K Hansma,et al.  Measuring the viscoelastic properties of human platelets with the atomic force microscope. , 1996, Biophysical journal.

[24]  W F Heinz,et al.  Relative microelastic mapping of living cells by atomic force microscopy. , 1998, Biophysical journal.

[25]  C Rotsch,et al.  Drug-induced changes of cytoskeletal structure and mechanics in fibroblasts: an atomic force microscopy study. , 2000, Biophysical journal.

[26]  J. Hoh,et al.  Surface morphology and mechanical properties of MDCK monolayers by atomic force microscopy , 1996 .

[27]  M. Radmacher,et al.  Imaging viscoelasticity by force modulation with the atomic force microscope. , 1993, Biophysical journal.

[28]  Ben Fabry,et al.  Microrheology of human lung epithelial cells measured by atomic force microscopy. , 2003, Biophysical journal.