Electrofusion of cell-size liposomes

Area of Science:

• Biophysics
• Membrane Science
• Liposome Technology

Background:

• Liposomes are crucial in drug delivery and biomimetic studies.
• Understanding liposome fusion is key to controlling membrane dynamics.
• Electrofusion offers a precise method for merging liposomes.

Purpose of the Study:

• To investigate the critical parameters influencing liposome electrofusion.
• To mathematically model fusion yields based on electrical and surface properties.
• To elucidate the roles of dipole-dipole attraction and electrostatic repulsion in electrofusion.

Main Methods:

• Liposomes composed of various phospholipids were prepared.
• Dielectrophoresis was used for liposome alignment.
• A high-voltage pulse of varying duration induced electrofusion.
• Fusion yields were quantified using microscopy.

Main Results:

• Fusion yields exhibited sigmoidal curves with a minimum pulse length of 19 microseconds.
• Increased external media conductivity and vesicle surface charge shifted fusion curves to longer pulse durations.
• Polymer type had minimal impact on fusion outcomes.
• Mathematical models accurately accounted for observed fusion behaviors.

Conclusions:

• Membrane potential breakdown is a prerequisite for electrofusion.
• Pulse-induced dipole forces are critical for electrofusion.
• Electrostatic repulsion acts as a barrier, particularly for charged liposomes.
• Vesicle size distribution influences electrofusion efficiency.