Alginate-Templated Microcapsules Carrying Heparin via Layer-by-Layer Self-Assembly

Electrostatic layer-by-layer self-assembly is a simple and effective approach to carry macromolecules into microscale carriers. Calcium-cross-linked alginate hydrogel microspheres were fabricated by an emulsification technique and then used as negatively charged templates for polyelectrolyte multilayer coatings to entrap heparin. The polycation was poly (allylamine hydrochloride) (PAH), while the polyanion was heparin, an anticoagulant to prevent the clotting of blood. The microcapsule was formed via coating {PAH/heparin}₃ on Ca²⁺-cross-linked alginate hydrogel. The retention of alginate in {PAH/heparin}₃ microcapsule was confirmed by fluorescence inverted microscopy and confocal laser scanning microscopy. The assembly of polyelectrolyte layers on alginate microspheres was monitored by Zeta Potential Analyzer. The concentration of heparin was detected by HPLC with IR-detector and organic acid column. It was found that heparin could be entrapped in the microcapsules in high efficiency, providing a useful delivery system which would be found potential application in antagonizing thrombosis.