Preparation and In Vitro Characterization of Alginate Microspheres Encapsulated with Autoclaved Leishmania major (ALM) and CpG -ODN

Objective The goal of this study was to prepare and characterize alginate microspheres as an antigen delivery system and adjuvant for immunization against leishmaniasis. Materials and Methods Microspheres were prepared by an emulsification technique and characterized for size, encapsulation efficiency, and release profile of encapsulates. Selection of appropriate parameters (viscosity of alginate, emulsifier, and sonication times) enabled the preparation of alginate microspheres with a mean diameter of 1.8 ± 1.0μm, as determined by Scanning Electron Microscopy and Particle Size Analyzer. Results The encapsulation efficiency was about 34.2 ± 6.7% for autoclaved leishmania major and 63.5 ± 6.9% for CpG-ODN, as determined by spectrophotometric assays. In vitro release profile showed a slow release rate for encapsulated ALM, while higher release rate was observed for CpG-ODN. The molecular weight was evaluated by SDS-PAGE and showed that the process of encapsulation did not affect the molecular weight of the entrapped antigen. Conclusion With regard to the optimum diameter (less than 5 μm), slow release rate and preservation of antigen molecules, alginate microspheres could be considered as a promising antigen delivery system for ALM.