Influence of partially cross-linked alginate used in the production of alginate microspheres by emulsification

Spherical and discrete calcium alginate microspheres had been produced by the emulsification technique. The microencapsulation process was highly efficient, but drug release from microspheres was rapid. A more orderly chain arrangement of the polymeric chains would give rise to a stronger and less permeable matrix capable of sustaining drug release. Therefore, the potential of using partially cross-linked alginate in the production of microspheres by emulsification was explored. The size and roundness of the microspheres, its drug content and drug release property were determined. The more viscous alginate solutions when reacted with more calcium salt added resulted in larger microspheres produced. Microspheres made from partially cross-linked alginate exhibited lower drug content and higher T75% values in drug release studies. This was due to decreased flexibility of the polymer chains which were partially held together by calcium ions, reducing subsequent interaction with the calcium ions resulting in lower drug entrapment efficiency and a more permeable microsphere matrix.