| Hydrogel systems of konjac glucomannan (KGM) crosslinked with trisodium trimetaphosphate (STMP) were prepared in this thesis for colon-targeting drug delivery. Swelling and crosslinking degrees, mechanical and thermodynamic properties of the hydrogels were characterized. In vitro release of different model drugs were studied in presence and absence ofβ-mannanase. Subsequently, drug release mechanism was discussed and kinetic model was set up. The main conclusions in this thesis were drawn as following.1. The optimum reaction condition of preparing phosphated KGM hydrogel was pH=11-11.5, STMP : KGM=0.3-2.5, 1-2%w/w KGM, NaCl : KGM=10%w/w, room temperature and 2h of crosslinking.2. Swelling and crosslinking degrees, Yount's modulus and melting temperature of the hydrogels were studied. We found that swelling of the hydrogels depended on both crosslinking and negative charges brought by STMP. Crosslinking density, Yount's modulus and melting temperature of the hydrogels were found to increase with the mount of STMP used in the reaction.3. In vitro release of model drugs hydrocortisone, BSA and cimetidine were studied in presence and absence ofβ-mannanase. The conclusion showed that the phosphated KGM hydrogel could retard the release of poorly water-soluble drugs and biomolecular drugs and could be degraded enzymatically. According to empirical modes, we also figured out that diffusion-erosion was the mechanism of drug release.4. A reservoir-like drug release system was fabricated using phosphated KGM membrane, and In vitro release of model drug cimetidine was evaluated in presence and absence ofβ-mannanase. It was concluded that the reservoir-like drug release system of phosphated KGM membrane could be potencial as an colon-specific vessel for soluble drugs. Based on the self-degradation model and the enzymatic model, the drug release kinetic process was simulated, and it was demonstrated in good agreement with the experimental results.
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