A general approach for the microrheology of cancer cells by atomic force microscopy

• Published in: Micron (Oxford, England : 1993) Vol. 44; pp. 287 - 297
• Main Authors: Wang, Biran, Lançon, Pascal, Bienvenu, Céline, Vierling, Pierre, Di Giorgio, Christophe, Bossis, Georges
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.01.2013; Elsevier
• Subjects: Atomic force microscopy; Biological Physics; Biomechanics and viscoelasticity; Cancer cell; Cell Behavior; Cell Line, Tumor; Cellular Biology; Condensed Matter; Elasticity; Engineering Sciences; Hep G2 Cells; Humans; Life Sciences; Liver Neoplasms; Materials; Materials Science; mathematical models; Microrheology; Microscopy, Atomic Force; Models, Biological; neoplasm cells; Physics; Rheology - methods; Stress, Mechanical; viscoelasticity; Viscosity; Cancer cell; Atomic force microscopy; Biomechanics and viscoelasticity; Microrheology
• ISSN: 0968-4328; 1878-4291
• DOI: 10.1016/j.micron.2012.07.006

► A general model to obtain the viscoelastic properties of a cell using AFM is proposed. ► It is exact for any time dependent displacement of the cantilever head. ► Its application to cancer cell reveals a short time relaxation not observed before. ► A power law model does not properly describe the creep relaxation function. ► A cut-off frequency appears in the shear modulus. The determination of the viscoelastic properties of cells by atomic force microscopy (AFM) is mainly realized by looking at the relaxation of the force when a constant position of the AFM head is maintained or at the evolution of the indentation when a constant force is maintained. In both cases the analysis rests on the hypothesis that the motion of the probe before the relaxation step is realized in a time which is much smaller than the characteristic relaxation time of the material. In this paper we carry out a more general analysis of the probe motion which contains both the indentation and relaxation steps, allowing a better determination of the rheological parameters. This analysis contains a correction of the Hertz model for large indentation and also the correction due to the finite thickness of the biological material; it can be applied to determine the parameters representing any kind of linear viscoelastic model. This approach is then used to model the rheological behavior of one kind of cancer cell called Hep-G2. For this kind of cell, a power law model does not well describe the low and high frequency modulus contrary to a generalized Maxwell model.