Preparation and in vitro evaluation of chitosan-coated alginate/calcium complex microparticles loaded with fluorescein-labeled lactoferrin.

An attempt was made to prepare FITC-labeled-lactoferrin (LF-FTC)-loaded microparticles, durable under gastrointestinal conditions, first by the combination of alginate/calcium complexation and emulsification-evaporation and next by treatment with chitosan solution. The obtained microparticles were examined for particle characteristics, in vitro release profiles and physical stability in solutions of pH 1.2 and 6.8. The obtained chitosan-coated alginate/calcium complex microparticles (Ch/Al/Ca-MP) showed almost uniform size of 1-2 microm and a spherical shape with a non-smooth surface. The content and recovery of LF-FTC in Ch/Al/Ca-MP fell as the concentration of chitosan solution used in chitosan coating increased. The release rate of LF-FTC was faster in Ch/Al/Ca-MP prepared with more chitosan at pH 1.2 and 6.8. Ch/Al/Ca-MP coated with 0.25 and 0.5% (w/v) chitosan solution showed good gradual release characteristics in vitro. Furthermore, they were durable at pH 1.2 and 6.8, though swelling and softening of the microparticles occurred at pH 6.8. It is suggested that alginate/calcium complex microparticles coated with 0.25-0.5% (w/v) chitosan solution would be useful for the intestinal delivery of LF.