Research About Chitosan Crosslinked By Genipin

The objective of oral colon-specific drug delivery system (OCDDS) is the specific delivery of drugs to the human colon via the oral route. Chitosan, which is a natural polymer with good biocompatibility, has a broad foreground in biomedicine industry. Especially because of the pH sensitivity, chitosan and its derivatives have potential applications in OCDDS field. In this paper, N-carboxymethyl chitosan/sodium alginate blend membranes crosslinked by genipin were prepared. Genipin is a natural crosslinking agent, which has less cell cytotoxicity, better crosslinking ability and durability to enzymatic degradation than the common crosslinking agent glutaraldehyde. This kind of drug carrier membranes reduced the side-effect of drug to gastrointestinal environment, and were of simple preparation. Based on this, sodium alginate microspheres were fabricated using the electrostatic spray technology. The environment friendly, symmetry and sphericity of the microspheres are superiority. Then the microspheres were coated in a chitosan solution and cross-linked by genipin. As a result, the genipin cross-linked N-carboxymethyl chitosan/sodium alginate microcapsules were collected. The Details and conclusions are described as follows:1, A series of blend membranes were prepared by a water-soluble chitosan (N-carboxymethyl chitosan, CS-AA) and sodium alginate (ALG) co-cross linked by genipin. Then the membranes loaded with drug (Fluorouracil,5-Fu) was produced with one method that is to add the drug into the blend of CS-AA/ALG before cross-linking with genipin, after that using UV specrum to test the drug release capability in different pH buffer solutions. The results indicated that the swelling ratio was slow in the strong acid medium due to formation of hydrogen bonds between CS-AA and alginate. At pH 7.4, the carboxylic acid groups on the CS-AA/ALG hydrogel became progressively ionized. In this case, the hydrogel swelled more significantly due to a large swelling force created by the electrostatic repulsion between the ionized acid groups. The release system released at pH 1.2 was relatively lower. The results suggested that the Chitosan-based hydrogel could be a suitable polymeric carrier for site-specific protein drug delivery in the colon.2, A series of sodium alginate microspheres were fabricated by changing the external voltage values, promote speed and needles dimensions of electrostatic spray technology. Then uniform grading microspheres with diameter of about 200μm were chosen in particle size analysis using laser granulometer. Then the microspheres were coated in a chitosan solution and cross-linked by genipin.The genipin cross-linked CS-AA/ALG microcapsules were collected. The characterization was studied by the fluorescence microscopy analysis, the confocal laser scanning microscopy analysis and SEM etc, and the optimal conditions of the microcapsules were determined. It is possible that the genipin cross-linked CS-AA/ALG microcapsules will be used as colon-specific carrier.