Chitosan-coated liposomes: characterization and interaction with leuprolide

Area of Science:

• Pharmaceutical Sciences
• Materials Science
• Biotechnology

Background:

• Liposomes are widely used drug delivery systems.
• Chitosan coating can enhance liposome properties.
• Understanding lipid type and chitosan concentration effects is crucial for optimizing liposomal formulations.

Purpose of the Study:

• To investigate how chitosan concentration and lipid purity influence chitosan-coated liposomes.
• To analyze the interaction between chitosan and liposomes with varying lipid purity.
• To evaluate the impact on physical characteristics, drug entrapment, and stability of leuprolide-loaded liposomes.

Main Methods:

• Preparation of liposomes using high and low purity lipids.
• Coating of liposomes with varying concentrations of chitosan.
• Characterization of physical properties (particle size, zeta potential).
• Assessment of drug entrapment efficiency and stability upon dilution.

Main Results:

• Liposomes from low purity lipid exhibited larger particle size increases and higher zeta potential, indicating thicker chitosan coatings and better resistance to flocculation.
• High purity lipid liposomes showed polymer bridging flocculation at low chitosan concentrations and steric stabilization at high concentrations.
• Drug entrapment efficiency decreased with increasing chitosan concentration due to bilayer disturbance.
• Leuprolide leakage upon dilution was greater from low purity lipid liposomes.

Conclusions:

• Low purity lipids, with their higher negative charge, form thicker adsorptive layers via stronger electrostatic attraction with chitosan.
• Chitosan interaction with phospholipid head groups can disrupt bilayers, affecting leuprolide entrapment and leading to leakage.
• Lipid purity significantly impacts chitosan coating effectiveness and drug retention in liposomal formulations.