Synthesis and surface characterization of functionalized polylactide copolymer microparticles

Area of Science:

• Biomaterials Science
• Polymer Chemistry
• Surface Science

Background:

• Poly(lactide) (PLac) is a biodegradable polymer with potential applications in drug delivery and tissue engineering.
• Copolymerization of PLac with amino acids can introduce specific functionalities and improve biocompatibility.
• Microemulsion techniques offer a method for synthesizing well-defined microparticles.

Purpose of the Study:

• To synthesize microparticles of poly(lactide) and its copolymers with serine (P(Lac-Ser)) and aspartic acid (P(Lac-Asp)).
• To characterize the surface chemistry of these microparticles using Fourier-transform infrared (FTIR) spectroscopy.
• To investigate the presence and location of hydrophilic functional groups on the microparticle surfaces.

Main Methods:

• Synthesis of poly(lactide) microparticles and copolymers using the solvent evaporation microemulsion technique.
• Stabilization of microparticles using poly(vinyl alcohol) (PVA) as a non-ionic surfactant.
• Surface characterization via FTIR transmission spectroscopy under vacuum at room and elevated temperatures.

Main Results:

• Microparticles with sizes around 200 nm were successfully synthesized.
• FTIR analysis confirmed the presence of PVA-derived hydroxy groups (3506 cm⁻¹) on the particle surfaces.
• Free hydroxy groups from serine residues (3396 cm⁻¹) and free carboxylic acid groups from aspartic acid residues (3387 cm⁻¹) were detected, indicating their migration to the surface.

Conclusions:

• The microemulsion technique effectively produced poly(lactide)-based microparticles with tunable surface functionalities.
• Hydrophilic groups from copolymerized amino acids (serine and aspartic acid) are accessible on the microparticle surfaces.
• These findings are crucial for designing advanced biomaterials with tailored surface properties for specific biomedical applications.