Frequency-dependent cellular microrheology with pyramidal atomic force microscopy probes.

Area of Science:

• Biophysics
• Cellular Mechanics
• Materials Science

Background:

• Atomic force microscopy (AFM) commonly measures cell elasticity using force-indentation curves.
• Cells exhibit time-dependent stress relaxation and frequency-dependent mechanical properties, vital for biological functions.
• Current AFM microrheology often requires specialized, expensive spherical probes.

Purpose of the Study:

• To develop a framework for using standard blunt pyramidal AFM probes for oscillatory microrheology.
• To enable accessible measurement of frequency-dependent cell mechanical properties.
• To validate the method with known standards and apply it to biological systems.

Main Methods:

• Derivation of expressions to extract rheological moduli from AFM data.
• Exploration of experimental calibration and parameter optimization for blunt probes.
• Oscillatory micro-indentation experiments on agarose hydrogels and cultured cells.

Main Results:

• Successful adaptation of blunt pyramidal AFM probes for oscillatory microrheology.
• Validation of the method using agarose hydrogel standards.
• Demonstration of measurable rheological changes in cells treated with cytoskeletal inhibitors (nocodazole, cytochalasin D).

Conclusions:

• The developed framework allows standard AFM probes to perform oscillatory microrheology.
• This method provides a more accessible approach to study dynamic cell mechanics.
• Findings offer insights into the contributions of cytoskeletal networks to cell rheology.