Vesicles of variable sizes produced by a rapid extrusion procedure.

Area of Science:

• Lipid-based nanocarrier formulation
• Biophysical characterization of vesicles

Background:

• Previous research established extrusion for producing large unilamellar vesicles.
• Optimization of vesicle production methods is crucial for drug delivery and research.

Purpose of the Study:

• To develop a versatile method for producing homogeneously sized unilamellar and plurilamellar vesicles.
• To enhance vesicle unilamellarity and trapping efficiency, particularly at high lipid concentrations.

Main Methods:

• Extrusion of multilamellar vesicles through polycarbonate filters (30-400 nm pores).
• Incorporation of a freeze-thaw step prior to extrusion.
• Characterization using freeze-fracture electron microscopy.

Main Results:

• Homogeneously sized vesicles produced across a range of filter pore sizes (30-400 nm).
• Freeze-thaw pretreatment significantly improved unilamellarity and trapping efficiency.
• High lipid concentrations (400 mg/ml) yielded trapping efficiencies of 56% (100 nm) and 80% (400 nm).
• Vesicle characteristics remained comparable to those produced at lower lipid levels.

Conclusions:

• The freeze-thaw and extrusion process is a superior technique for producing vesicles of variable sizes.
• This method offers high trapping efficiency, making it ideal for various applications.
• The technique is particularly effective for high-concentration lipid formulations.