Electrostatics of carboxylated anionic vesicles for improving entrapment capacity

Area of Science:

• Biochemistry
• Materials Science
• Nanotechnology

Background:

• Lipid vesicles (liposomes) are crucial for drug delivery.
• Electrostatic interactions significantly influence vesicle properties.
• Anionic vesicles offer unique characteristics for encapsulation.

Purpose of the Study:

• To investigate the relationship between the electrostatics of carboxylated anionic vesicles and their entrapment capacity.
• To determine the optimal zeta potential for maximizing the encapsulation of water-soluble markers.
• To understand the structural basis for high entrapment capacity in these vesicles.

Main Methods:

• Preparation of anionic vesicles by mixing a negatively charged lipid with phospholipid.
• Determination of vesicle electrostatics, specifically zeta potential.
• Correlation analysis between zeta potential and entrapment capacity for a water-soluble marker.
• Transmission electron microscopy (TEM) to analyze vesicle structure.

Main Results:

• Zeta potential was identified as a key factor quantitatively affecting entrapment capacity.
• Maximum entrapment capacity was achieved at a zeta potential less than -30 mV.
• Vesicles exhibiting high entrapment capacity were characterized by a unilamellar membrane structure.
• Carboxylated anionic vesicles (approx. 200 nm diameter) were successfully prepared and analyzed.

Conclusions:

• The zeta potential of anionic vesicles directly impacts their ability to entrap water-soluble substances.
• Anionic vesicles with zeta potential < -30 mV are highly efficient for encapsulating water-soluble markers.
• Unilamellar structure is associated with high entrapment efficiency in these vesicles.
• These findings support the use of anionic vesicles for efficient encapsulation of water-soluble pharmaceuticals.