New insights into poly(lactic-co-glycolic acid) microstructure: using repeating sequence copolymers to decipher...

Area of Science:

• Polymer Chemistry
• Materials Science
• Biomaterials Engineering

Background:

• Nature extensively utilizes sequence in biological polymers.
• Synthetic copolymer sequence control remains underexplored.
• Poly(lactic-co-glycolic acid) (PLGA) is crucial for biomedical applications due to its biocompatibility.

Purpose of the Study:

• To investigate the impact of sequence and stereosequence on PLGA physical properties.
• To explore sequence engineering for advanced copolymer design.
• To correlate sequence variations with NMR and thermal characteristics.

Main Methods:

• Synthesis of isotactic, syndiotactic, and atactic PLGA copolymers with defined repeating units (LG, GLG, LLG).
• Utilized sequence-specific, stereopure dimeric, trimeric, and hexameric segmer units for controlled polymerization.
• Characterization using Nuclear Magnetic Resonance (NMR) spectroscopy and thermal analysis.

Main Results:

• NMR analysis revealed sequence-dependent conformational effects, particularly in glycolic unit methylene resonances.
• High-resolution NMR (octad level) demonstrated sensitivity to stereocenters up to 31 atoms apart.
• Thermal properties were found to be directly correlated with the specific copolymer sequence.

Conclusions:

• Controlled sequence and stereosequence engineering significantly influence PLGA copolymer properties.
• NMR spectroscopy is a powerful tool for elucidating sequence-structure relationships in complex copolymers.
• This work provides a foundation for designing advanced sequence-controlled PLGA for targeted biomedical applications.