Characterization of insulin-loaded liposome using column-switching HPLC

Area of Science:

• Pharmaceutical Sciences
• Analytical Chemistry
• Biotechnology

Background:

• Accurate determination of drug encapsulation efficiency (EE) is crucial for liposome formulation development.
• Conventional methods like ultracentrifugation may not differentiate between surface-adsorbed and encapsulated drugs.
• Insulin (INS)-loaded liposomes are a key area for improving diabetes treatment delivery.

Purpose of the Study:

• To evaluate a novel column-switching High-Performance Liquid Chromatography (HPLC) system for assessing the drug-encapsulation state of insulin (INS)-loaded liposomes.
• To compare the accuracy of the novel HPLC method with conventional ultracentrifugation for EE determination.
• To investigate the influence of dispersion pH on the accuracy of EE measurements.

Main Methods:

• Development and application of a novel column-switching HPLC system utilizing hydrophobic interaction for drug separation.
• Characterization of INS-loaded liposomes using particle size analysis, zeta potential measurements, and transmission electron microscopy (TEM).
• Comparison of EE measurements obtained from the column-switching HPLC and ultracentrifugation methods at different pH conditions (pH 7.4 and pH 3.3).

Main Results:

• The column-switching HPLC system showed consistent EE results with ultracentrifugation in neutral conditions (pH 7.4).
• A significant disagreement in EE was observed between the two methods when liposomes were dispersed in acidic conditions (pH 3.3).
• Particle size, zeta potential, and TEM data supported the hypothesis that the HPLC method accurately distinguishes surface-adsorbed INS from encapsulated INS.

Conclusions:

• The novel column-switching HPLC system accurately differentiates between insulin adsorbed onto the liposome surface and encapsulated insulin.
• Ultracentrifugation may co-precipitate surface-adsorbed insulin, leading to inaccurate EE measurements in certain conditions.
• The column-switching HPLC system offers a more accurate and valuable technique for the characterization and optimization of insulin-loaded liposome formulations.