Determining the Elastic Modulus of Biological Samples using the Atomic Force Microscope

^{KEYWORDS: Atomic Force Microscopy; AFM; NanoWizard; CellHesion; Elastic Modulus; Young's Modulus; Hertz Model; Nanoindentation; Living Cells; Life Science}

Using the atomic force microscope (AFM) for nanoindentation has emerged as a useful tool to determine elastic properties like the elastic modulus for biological samples. Cantilevers serve as soft nanoindenters allowing local testing if small and heterogenous samples like cells or tissues. To calculate the parameter of interest various models are used, but most of them are based on the Hertz model and extended to match the experimental conditions concerning the indenters’ shape or the thickness of the sample.

Nanomechanical analysis of cells is becoming increasingly important in different fields like cancer and developmental biology. The potential of this methodology is widely used in biological disciplines to describe elastic properties of different matrices and materials.

This application note describes the application and acquisition of elasticity experiments using AFM. An overview of the most commonly used model, the Hertz model, is given and the assumptions and resulting limitations for the use with biological samples is discussed in detail.

Readers can expect to learn about:

• The Hertz model as the most commonly used model for elasticity experiments and it's limitations when applied to biological samples;
• Detailed step-by-step description of nanoindentation experiments including used cantilevers, instrumention and testing methods; and
• How Bruker's CellHesion and NanoWizard AFM systems in combination with dedicated accessories and an intuitive software deliver the perfect tools for elasticity experiments on living cells and other biological samples;