Subsurface Imaging of Cell Organelles by Force Microscopy

Area of Science:

• Cellular and Molecular Biophysics
• Nanotechnology
• Microscopy

Background:

• High-resolution, label-free, noninvasive microscopy of living cells, especially subsurface structures, is challenging.
• Current force-microscopy stiffness measurements primarily reflect outer cell structures (plasma membrane, cytoskeleton), limiting intracellular imaging.
• Understanding single-cell nanomechanics requires probing both external and internal cellular components.

Purpose of the Study:

• To overcome the limitations of conventional stiffness measurements in imaging intracellular structures.
• To develop a method for simultaneous imaging of the cell's outer cytoskeleton and internal nuclear organelles.
• To combine 2D sections of cell viscoelastic properties for enhanced subsurface imaging.

Main Methods:

• Utilizing force-microscopy to measure the viscoelastic properties of living cells.
• Analyzing both the elastic and inelastic components of the interaction force.
• Developing a method to combine 2D viscoelastic data for subsurface imaging.

Main Results:

• Demonstrated simultaneous imaging of the outer cell's cytoskeleton and intracellular organelles within the nucleus.
• Showcased that the elastic force component reflects outer cell structures (cortex, actin cytoskeleton).
• Revealed that the inelastic force component is sensitive to the hydrodynamic drag of internal structures like nucleoli.

Conclusions:

• Combining 2D viscoelastic property sections enables noninvasive subsurface imaging of cellular components.
• This technique advances the understanding of single-cell nanomechanics by differentiating contributions from outer and inner cell structures.
• The method offers a pathway for high-resolution, label-free imaging of living cells, including their internal organelles.