Mechanical response analysis and power generation by single-cell stretching.

Area of Science:

• Biophysics
• Cell Biology
• Mechanobiology

Background:

• Understanding cell response to mechanical forces is crucial for physiological processes.
• Existing techniques lack precision in applying controlled mechanical stimuli to single cells.
• Investigating cellular mechanics requires stable, long-term experimental setups.

Purpose of the Study:

• To design and validate a cantilever-based technique for precise mechanical perturbation of single cells.
• To quantitatively analyze cell response to applied forces and deformations in vitro.
• To discriminate between passive viscoelastic deformation and active cellular responses.

Main Methods:

• Utilized a cantilever-based system for automated force application and deformation detection.
• Employed fiber-optical force sensing and closed-loop control for precise measurements.
• Maintained experimental stability by eliminating thermal gradients in a 37°C cell observation chamber.
• Simultaneously visualized cell shape and intracellular morphology using optical microscopy.

Main Results:

• Measured active power generated during cell contraction (Pmax ≈ 10⁻¹⁶ W), corresponding to ~2500 ATP molecules/sec.
• Estimated the ratio of contractive to dissipative power to be approximately 10⁻².
• Determined that cellular forces involve ~10⁴ molecular motors, indicating ~0.5 energy conversion efficiency.
• Observed increased cytoskeleton crosslinking in response to mechanical pulling.

Conclusions:

• The developed technique allows for detailed quantitative analysis of single-cell mechanical behavior.
• Mechanical stimulation leads to both recruitment of contractile elements and increased cytoskeleton crosslinking.
• The findings provide data for validating physical models of cellular mechanical responses.