| Summary: | A new carrier system for controlled release of immunologic peptides based on double polysaccharide film-coated microparticles (PCMPs) used with liquid products was developed. The release behavior of PCMPs was shown dependent on the thicknesses of the outer chitosan film and the inner resistant starch acetate (RSA) film. The in-vitro release results indicated that, with optimized polysaccharide coating thickness (RSA: 4–5%; chitosan: 6–7%), the release rate of Thymopoietin (TP5) was less than 30% before the microparticles reached the colon, and was 50% in the colon. Besides, the bioavailability of PCMPs was evaluated based on the cell proliferation and protein expression. Compared with the intraperitoneal injection or oral administration, the immunodeficient rats that were orally administrated with the yogurt containing TP5-loaded PCMPs with different storage times possessed a good colon-targeting behavior, higher ratios of CD4/CD8 and IgG expression, indicating the improvement in the TP5 immunologic function.
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