Effects of Non-ionic Surfactant on the Release of Protein Drug from poly(DL-lactide-co-glycolide) Microspheres

Abstract

To modify the release of antigen from PLGA microspheres, non-ionic surfactants were added during microencapsulation process of diphtheria toxoid. Antigen loading efficiencies were similar in all microspheres regardless of surfactant addition in the range of 70 to 80%. However, the other parameters including surface antigen, interfacial partitioning and particle size were quite different. The surfactant-added microspheres showed greater amount of surface antigen than the surfactant-free microsphere, suggesting that the surfactant had a key role in partitioning of the antigen between two phases in water-in-oil primary emulsion. In comparison to the control microsphere, surfactant-added microspheres revealed the biphasic release pattern which is demonstrated by the gradual increases in antigen release after initial burst effect. Particularly PLGA microspheres with Span 65 resulted in the greatest surface antigen due to hydrophobic interactions between Span 65 and the antigen at the interface and continuously released the antigen up to 90% over the extended period of time.