Electron microscopic studies on cell-sized bilayer liposomes

Area of Science:

• Biophysics
• Cell Biology
• Materials Science

Background:

• Liposomes are crucial in drug delivery and biomimetic research.
• Direct visualization of cell-sized liposomes presents technical challenges.
• Understanding liposome structure is key to optimizing their function.

Purpose of the Study:

• To develop and apply a method for direct electron microscopic visualization of cell-sized liposomes.
• To characterize the ultrastructure and measure the thickness of these liposomes.

Main Methods:

• Utilized a thin section electron microscopy technique.
• Employed a fixation protocol involving lanthanum nitrate and potassium permanganate.
• Analyzed images using microdensitometer tracings for thickness measurements.

Main Results:

• Successfully visualized cell-sized bilayer liposomes in thin sections.
• Observed distinct trilamellar images, indicative of lipid bilayer structure.
• Measured liposome thickness (peak-to-peak distance) between 25.3 and 55.3 Å.
• Determined a mean thickness of 35.6 ± 8.2 Å, consistent with known lipid bilayer models.

Conclusions:

• The developed fixation and thin sectioning method enables direct electron microscopic visualization of cell-sized liposomes.
• The observed trilamellar structure and measured thickness support the model of liposomes as lipid bilayers.
• This technique provides a valuable tool for studying liposome morphology and stability.