Nanobiomechanics of living cells: a review

Abstract

Nanobiomechanics of living cells is very important to understand cellmaterials interactions. This would potentially help to optimize the surface design of the implanted materials and scaffold materials for tissue engineering. The nanoindentation techniques enable quantifying nanobiomechanics of living cells, with flexibility of using indenters of different geometries. However, the data interpretation for nanoindentation of living cells is often difficult. Despite abundant experimental data reported on nanobiomechanics of living cells, there is a lack of comprehensive discussion on testing with different tip geometries, and the associated mechanical models that enable extracting the mechanical properties of living cells. Therefore, this paper discusses the strategy of selecting the right type of indenter tips and the corresponding mechanical models at given test conditions.

Nanomechanics of Cells and Biomaterials Studied by Atomic Force Microscopy

“…Other models such as the Tatara model have been developed for large strain indentation and have been applied to the indentation of proteins and cartilage, whilst the Oliver‐Pharr method has been used to study the modulus of bone . A review of non‐continuum based models see is provided by Chen …”

“…Biological materials such as cells, native and engineered ECMs are complex hierarchical materials which can exhibit dramatically different moduli over multiple lengthscales and timescales. As such, mechanical characterization to obtain a single modulus number that is representative of a sample is often infeasible . Despite this difficulty, it is not uncommon to find reports of mechanical properties of biomaterials determined by AFM based on improper experimental methods and the application of inappropriate models, which are either incorrect or irrelevant to the chosen application.…”

The Roles of Cellular Nanomechanics in Cancer

“…A recent review article describes in detail the use of nanoindentation and its function, appropriate mechanical models used to test the indentation measurements at given test conditions, and suitable types of tip geometries helpful to measure indentations specifically on living cells . In this section, we provide detailed information on conventional use of nanoindentation, function of nanoindentation, typical mechanical models used, and various factors that influence measurements.…”

“…This methodology is used to obtain a force–displacement curve in a three‐step process: (i) approach: AFM probe/tip brought close to the cellular surface, (ii) contact or indent (compression step): indentation into the cell surface provides interaction between the cell‐surface proteins and the tip, and (iii) retraction or separation (decompression step): retraction/separation from the surface of the cell allows extension of the bound macromolecule(s) as the tip–cell distance . Nanoindentation data are highly influenced by the tip/cantilever type, substrate, mechanical model used, and in vitro/in vivo physiological condition . A spherical indenter is recommended for biological tissues/cells to enable small stress concentrations, while a sharp tip indenter suits relatively hard materials including dental and bone samples .…”

Nanobiomechanics of living materials

“…Chen [11] has reviewed the most cutting-edge nanoindentation methods, combined with suitable mechanical models for quantitative analysis of elastic properties and time-dependent behaviours of single biological cells. A comprehensive appraisal has also been given to the merits and demerits of the various mechanical models including the tensegrity model, percolation model, elastic model, viscoelastic model, power-law rheology model, poroelastic (biphasic) and triphasic model.…”