Stiffness tomography by atomic force microscopy.

Area of Science:

• Biophysics
• Materials Science
• Nanotechnology

Background:

• Atomic Force Microscopy (AFM) is a key tool for nanoscale analysis of biological samples.
• AFM can function as a nano-indenter to measure mechanical properties like Young's modulus.
• Current methods face challenges in differentiating subsurface structures of varying stiffness.

Purpose of the Study:

• To present a new technique for processing nano-indentation curves obtained from AFM.
• To enable the distinction of buried structures with different stiffness within a sample.
• To validate the technique using computational models and apply it to living cells.

Main Methods:

• Utilizing AFM in nano-indentation mode to collect force-deformation data.
• Developing a novel curve-processing method to analyze mechanical heterogeneity.
• Employing finite element modeling for theoretical validation.
• Applying the technique to image mechanical properties of living cells.

Main Results:

• The new technique successfully distinguishes structures of different stiffness within bulk samples.
• Finite element models confirmed the working principle of the imaging method.
• The technique was successfully applied to living cells, demonstrating its practical utility.

Conclusions:

• The developed AFM-based technique offers enhanced capabilities for probing mechanical properties of biological samples.
• This method allows for the differentiation of subsurface structures based on stiffness.
• The validated technique provides a valuable tool for nanoscale biomechanical investigations.