AFM-based spherical indentation of a brush-coated soft material: modeling the bottom effect

Area of Science:

• Biophysics
• Cell Mechanics
• Nanotechnology

Background:

• Atomic Force Microscopy (AFM) is used to study living cells' mechanical properties, often by measuring their elastic (Young's) modulus.
• Cell indentation by AFM is influenced by the distance to the substrate (bottom effect) and the presence of molecular brushes on the cell surface.

Purpose of the Study:

• To develop a mathematical model for calculating the intrinsic effective Young's modulus of brush-coated cells.
• To incorporate the 'bottom effect' into the AFM-based mechanical characterization of single cells.

Main Methods:

• Development of a novel mathematical model for force-indentation data analysis.
• Integration of the 'bottom effect' into the model for accurate Young's modulus determination.
• Application of the model to experimental AFM data from an eukaryotic cell.

Main Results:

• The model successfully determines the intrinsic Young's modulus of a brush-coated cell.
• The model accounts for the influence of the substrate proximity on cell mechanics.
• Demonstrated the model's utility with a real-world eukaryotic cell example.

Conclusions:

• The developed mathematical model provides a more accurate method for assessing cell mechanics via AFM.
• Understanding intrinsic cell elasticity is crucial for cell differentiation and function studies.
• This approach enhances the interpretation of AFM data in cell biology and biophysics.