Liposomes prepared dynamically by interactions between bile salt and phospholipid molecules.

Area of Science:

• Biophysics
• Materials Science
• Pharmaceutical Sciences

Background:

• Mixed micelles composed of sodium glycocholate and egg phosphatidylcholine are known to form structures in solution.
• Drug delivery systems often require efficient methods for encapsulating therapeutic agents into carriers like vesicles.
• Understanding the self-assembly of lipid-based structures is crucial for developing novel drug delivery platforms.

Purpose of the Study:

• To investigate the spontaneous formation of vesicles from sodium glycocholate-egg phosphatidylcholine mixed micelles upon dilution.
• To evaluate the influence of a water-soluble drug, cytosine arabinoside, on this vesicle formation process.
• To assess the potential of this transition as a method for loading drugs into vesicles.

Main Methods:

• Quasi-elastic light scattering (QELS) was employed to study the size and formation of vesicles.
• Transmission electron microscopy (TEM) was used to determine vesicle diameter.
• Dilution experiments were conducted using physiological saline buffer and diluted serum solutions.

Main Results:

• Vesicles spontaneously formed from mixed micelles upon dilution with buffer or serum.
• The presence of cytosine arabinoside did not alter the transition pattern.
• Constant intermicellar bile salt monomer concentration suppressed vesicle formation.
• Drug loading efficiency was approximately 10% in buffer and 2.5% in serum.
• QELS and TEM measurements showed good correlation in vesicle diameter.

Conclusions:

• The spontaneous mixed micelle to vesicle transition is a viable method for in vitro vesicle formation.
• This transition offers a potential alternative to sonication for loading drugs into vesicles.
• The efficiency of drug encapsulation is influenced by the diluent composition.