Dynamics of membrane nanotubulation and DNA self-assembly

Area of Science:

• Biophysics
• Materials Science
• Nanotechnology

Background:

• Vesicular membranes are fundamental biological structures.
• Understanding membrane mechanics is crucial for cell biology and drug delivery.
• Nanotubulation is a key process in cellular communication and membrane remodeling.

Purpose of the Study:

• To investigate the mechanical response of vesicular membranes to localized forces.
• To characterize the transition from elastic deformation to nanotubulation and flow.
• To explore the potential of optically induced nanotubules as probes for membrane dynamics and self-assembly.

Main Methods:

• Application of localized, point-like forces perpendicular to vesicular membrane layers using optical tweezers.
• Analysis of force-extension curves to identify elastic and flow regimes.
• Introduction of oscillatory forces to probe resonant frequencies in the flow phase.

Main Results:

• A force threshold was identified, above which membrane nanotubulation occurs.
• Below the threshold, membranes exhibit elastic behavior with serrations; above, a reversible viscoelastic flow phase emerges.
• Resonances in the flow phase suggest coupling between the vesicle-nanotubule system and applied forces, providing insights into time scales.

Conclusions:

• Optical tweezers can induce and control membrane nanotubulation, revealing distinct mechanical regimes.
• The observed viscoelastic flow phase offers a new platform for studying membrane dynamics.
• Optically tethered nanotubules serve as a novel tool for real-time observation of DNA self-assembly on membranes.