Indenting soft samples (hydrogels and cells) with cantilevers possessing various shapes of probing tip
- PDF / 3,271,305 Bytes
- 11 Pages / 595.276 x 790.866 pts Page_size
- 55 Downloads / 154 Views
ORIGINAL ARTICLE
Indenting soft samples (hydrogels and cells) with cantilevers possessing various shapes of probing tip Joanna Zemła1 · Justyna Bobrowska1 · Andrzej Kubiak1 · Tomasz Zieliński1 · Joanna Pabijan1 · Katarzyna Pogoda1 · Piotr Bobrowski2 · Małgorzata Lekka1 Received: 24 February 2020 / Revised: 6 May 2020 / Accepted: 11 August 2020 / Published online: 17 August 2020 © The Author(s) 2020
Abstract The identification of cancer-related changes in cells and tissues based on the measurements of elastic properties using atomic force microscopy (AFM) seems to be approaching clinical application. Several limiting aspects have already been discussed; however, still, no data have shown how specific AFM probe geometries are related to the biomechanical evaluation of cancer cells. Here, we analyze and compare the nanomechanical results of mechanically homogenous polyacrylamide gels and heterogeneous bladder cancer cells measured using AFM probes of various tip geometry, including symmetric and non-symmetric pyramids and a sphere. Our observations show large modulus variability aligned with both types of AFM probes used and with the internal structure of the cells. Altogether, these results demonstrate that it is possible to differentiate between compliant and rigid samples of kPa elasticity; however, simultaneously, they highlight the strong need for standardized protocols for AFM-based elasticity measurements if applied in clinical practice including the use of a single type of AFM cantilever. Keywords Atomic force microscopy (AFM) · Cancer cell mechanics · Indenter geometry
Introduction The biological functionality of cells and tissues is strongly correlated with their nanomechanical properties, usually quantified by Young’s modulus—a physical parameter describing the material’s resistance to elastic deformations (Sneddon 1965). One of the tools for studying cell mechanics in conditions close to physiological ones is atomic force microscopy (AFM). In most cases, for the data recorded using AFM-based force spectroscopy, Young’s modulus is evaluated in the frame of Hertz contact mechanics, which describes the deformation (indentation) of two purely elastic spheres. The model can be extended into a case when a stiff sphere indents an infinitely thick, isotropic and elastic * Joanna Zemła [email protected] * Małgorzata Lekka [email protected] 1
Institute of Nuclear Physics Polish Academy of Sciences, PL‑31342 Kraków, Poland
Institute of Metallurgy and Materials Science Polish Academy of Sciences, PL‑30059 Kraków, Poland
2
half-space in the absence of adhesion within the contact area (Hertz 1881). Sneddon’s modifications resolved the problem of indenter geometry by solving the Boussinesq problem, i.e., finding the elastic state in a linearly elastic isotropic half-space, subjected to a concentrated load applied in a point of its boundary plane and perpendicular to it, assuming various axisymmetric geometries of the indenters of various shapes (Sneddon 1965). One of the main requ
Data Loading...
