Stick, stretch, and scan imaging method for DNA and filaments

Area of Science:

• Mechanobiology
• Cell Biology
• Biophysics

Background:

• Biomolecules and organelles change structure under mechanical forces, crucial for mechano-chemical coupling and signal transduction.
• Observing these dynamic structural changes typically requires sophisticated techniques and labeling.

Purpose of the Study:

• To develop a simple, label-free method for observing fine structures of biomolecules after mechanical stretching.
• To visualize structural changes in DNA and cellular components with high resolution.

Main Methods:

• Attaching magnetic microbeads to DNA or cell surface molecules.
• Applying a magnetic field to stretch the bound molecules.
• Fixing, staining, and drying samples for scanning electron microscopy (SEM).

Main Results:

• Observed straight DNA strands, indicating successful stretching, unlike random-walk polymers.
• Visualized a 41.3 μm filament pulled from a cell filopodium via integrin.
• Demonstrated the ability to resolve structures up to hundreds of micrometers at nanometer resolution.

Conclusions:

• The developed method provides a simple and effective way to observe fine structures after mechanical manipulation without fluorophore labeling.
• This technique has broad applications in structure-function studies of biomolecules and in mechanobiology and cell biology.