Analysis of semi-solvent effects for PLGA polymers

Area of Science:

• Polymer Chemistry
• Materials Science
• Biomedical Engineering

Background:

• Poly(lactide-co-glycolide) polymers (PLGAs) are crucial for injectable, long-acting drug formulations.
• Characterizing and separating diverse PLGA components in mixtures is challenging due to incomplete understanding of their properties.

Purpose of the Study:

• To develop methods for separating PLGA polymers based on molecular properties like L:G ratio, molecular weight, and comonomer sequence.
• To identify effective semi-solvents for PLGA separation and understand their dissolution mechanisms.

Main Methods:

• Utilized semi-solvents that selectively dissolve PLGAs with lactide content (L%) above specific thresholds.
• Identified new semi-solvents exhibiting transition L% between 50% and 100%.
• Investigated solvent properties, including molar volume, and chemical class (esters vs. ketones), for optimal PLGA dissolution.

Main Results:

• Discovered semi-solvents that effectively separate PLGAs based on L:G ratio, molecular weight, and comonomer sequence (preferring G-L over G-G).
• Determined that lower molar volume solvents are more effective semi-solvents.
• Found esters to be more effective than ketones at similar molar volumes for dissolving PLGAs with identical L:G ratios.

Conclusions:

• Developed a method to separate and characterize individual PLGA fractions from mixtures.
• This technique enhances the characterization of existing PLGA-based formulations.
• Enables greater flexibility in designing novel injectable, long-acting PLGA formulations with tailored properties.