Nanoscale phase behavior on flat and curved membranes

Area of Science:

• Biophysics
• Membrane Biophysics
• Soft Matter Physics

Background:

• Membrane physical properties critically influence biological processes.
• Lateral membrane order and protein segregation depend on membrane phase.
• Understanding membrane phase dynamics is key to membrane-associated functions.

Purpose of the Study:

• To investigate local phase transitions in giant unilamellar lipid vesicles (GUVs) using optical trapping.
• To explore passive transport mechanisms in protein-free lipid bilayers.
• To study the generation of membrane curvature and its effect on phase transition temperature.

Main Methods:

• Utilizing optical trapping of gold nanoparticles to induce local heating and phase transitions in GUVs.
• Employing phase-sensitive fluorophores to image membrane dynamics and pore formation.
• Applying optical pulling forces to generate tubular membrane curvatures.

Main Results:

• Demonstrated localized and transient pore formation in a one-component lipid bilayer, mediating passive transport of fluorescent molecules.
• Showcased the generation of tubular membrane curvatures via optical pulling from melted GUV regions.
• Established a method to measure the impact of membrane curvature on phase transition temperature.

Conclusions:

• Optical trapping provides a precise method to locally perturb GUVs and study membrane properties.
• Lipid bilayers can exhibit passive transport through transient pores induced by localized melting.
• Membrane curvature significantly influences lipid phase behavior and transition temperatures.