Novel Hollow Microcapsules Based on Iron-Heparin Complex Multilayers

Iron-polysaccharide complex have been extensively utilized in the treatment of iron deficiency anemia for parenteral administration. Herein, a novel iron-heparin complexed hollow capsules with nanoscaled wall thickness have been fabricated by means of alternating deposition of ferric ions (III) (Fe3+) and heparin (Hep) onto the surface of submicroscaled (488 nm) and microscaled (10.55 mu m) polystyrene latex particles via both electrostatic interaction and chemical complexation processes, followed by dissolution of the cores using tetrahydrofuran. Confocal micrographs and atomic force microscopy (AFM) images prove that iron-heparin complexed submicroscaled hollow capsules keep spherical shapes in solution and even after drying. The activated partial thromboplastin time (APTT) assay shows that complexing with ferric ions do not compromise the catalytic capacity of heparin to promote antithrombin III-mediated thrombin inactivation. The anticoagulant activity value of (Fe3+/Hep)(8) capsules is evaluated to be about 95.7 U/mg, indicating that approximately 0.55 mg heparin was in 1 mg powder of submicroscaled (Fe3+/Hep)(8) hollow capsules. Compared with the same dosage of heparin, iron-heparin complexed hollow capsules display a more prolonged anticoagulant duration than heparin. All these results reveal that such submicroscaled iron-heparin complexed hollow capsules have application potential as an injectable anticoagulant vehicle.