Effect of liposome-albumin coatings on ferric ion retention and release from chitosan beads.

Ferric chloride was embedded in a chitosan matrix to develop a prolonged-release form. The in vitro release profiles of ferric ions from chitosan beads were monitored in 0.1 M Tris-HCl buffer, pH 7.4, using a UV spectrophotometer. The amount of drug release was much higher initially, followed by a constant slow release profile for a prolonged period. The initial burst release was substantially modified with liposome and albumin coatings. From scanning electron microscope studies, it appears that the ferric ions diffuse out slowly to the dissolution medium through the micropores of the chitosan matrix. Further, the liposome forms a phospholipid membrane layer in the pores of chitosan beads and encapsulates the ferric ions within their vesicles and controls the release profile. The chitosan beads loaded with ferric ions substantially inhibited the polyurethane-associated calcification, in an in vitro model system. The released ferric ions, appeared to alter the protein-surface binding and improved the biocompatibility of the matrix. The results propose the possibility of modifying the polymer matrix to obtain a desired controlled release of the drug for a prolonged period.