Effect of surfactant on the characteristics of biodegradable microcapsules

The objective of this project was to evaluate the effect of several lipophilic surfactants on the characteristics of PLGA microcapsules. BSA was used as a model peptide. Seven different lipophilic surfactants were used and each of the surfactants was used at three different concentrations, 0.1, 0.5 and 1% (w/w), respectively. The microcapsules were prepared using the double emulsion solvent evaporation technique. The microcapsules were all spherical in shape with a smooth surface. The median size of the microcapsules varied between 4 and 49 microm. The zeta potential of the microcapsules varied between -26 and -43 mV. The efficiency of encapsulation varied between 8 and 45%. Efficiency of encapsulation appears to be dependant on both the type and concentration of the surfactant. Cumulative percent of BSA released up to 35 days varied from 18 to 78%. In conclusion, the physical characteristics of the microcapsules do not appear to be greatly affected by the type of surfactant. All of the samples appear to show polydispersity in their particle sizes. Particle charge depended on both the type and concentration of the surfactant. The overall dissolution of these microcapsules was very slow.