Optimization of preparative conditions for polylactide (PLA) microspheres containing ovalbumin

Area of Science:

• Biomaterials Science
• Drug Delivery Systems
• Polymer Chemistry

Background:

• Polylactide (PLA) microspheres are investigated for controlled protein delivery.
• Ovalbumin (OVA) serves as a model protein to evaluate encapsulation and release characteristics.
• The water-in-oil-in-water (w/o/w) emulsion solvent evaporation method is employed for microsphere preparation.

Purpose of the Study:

• To optimize the preparation of PLA microspheres for enhanced ovalbumin (OVA) loading and controlled release.
• To investigate the impact of various formulation parameters on microsphere characteristics.
• To assess the potential of PLA microspheres as a long-acting protein delivery system.

Main Methods:

• Optimization of internal aqueous phase volume and external NaCl concentration for improved OVA loading efficiency.
• Evaluation of OVA release profiles from PLA microspheres with varying molecular weights and lactide/glycolide (LA/GA) ratios.
• Analysis of the effect of microsphere particle size on initial burst release and long-term OVA retention.

Main Results:

• Reduced internal aqueous phase volume and addition of 2-10% NaCl significantly increased OVA loading efficiency.
• PLA microspheres exhibited an initial burst release followed by a sustained OVA release for at least 28 days.
• Lower molecular weight PLA and smaller microsphere diameters (e.g., 5.0 microns) led to faster initial release but retained significant OVA over 28 days.

Conclusions:

• Formulation parameters like internal phase volume, NaCl concentration, and PLA molecular weight critically influence OVA loading and release kinetics.
• PLA microspheres demonstrate potential as effective long-acting delivery systems for proteins.
• Particle size reduction can modulate initial release rates, offering tunable delivery profiles.