Enhancement Of Controlled Release For Alginate-chitosan Microcapsules Using Enzymatically Hydrolyzed Glucomannan

The process of konjac glucomannan (KGM) hydrolysis by β-mannanase was studied in this thesis. Enhancement of controlled-release for alginate (ALG)-chitosan(CHI) microcapsules by enzymatically hydrolyzed glucomannan(EHG) was investigeted. Bull serum albumin (BSA) and nimodipine solid dispersion were used as a model protein for in vitro assessment. The interaction among enzymatically hydrolyzed glucomannan and alginate and chitosan was also discussed.The experiment of konjac glucomannan hydrolyzed by β-mannanase indicated that the Michaelis constant (Km )and the maximum reaction rate were 8.27 mg/ml and 0.0221 mg/ml.min respectively under enzymatic activity 200U/l. Dynamic viscosity decreased rapidly but reducing sugar changed a little during initial reaction. The reaction stopped after 1 hour when enzymatic activity 225U/l and substrate 10mg/ml hydrolysis temperature 40℃. Chromatographic analysis demonstrated that the molecular weight distribution of EHG was approximately normal distribution, and the average molecular of KGM hydrolyzed for 2min and 5min were about 1500000 and 700000 respectively. The mixture of ALG and KEM had higher viscosity. There was relatively strong interaction between ALG and EHG and CHI by the graph of infrared (IR). The process of KGM hydrolysis by β-mannanase could be expressed by IR. The scanning electron microscopy (SEM) micrograph indicated that non phase separation exists between ALG and EHG (5min) within microcapsules and the quantity of CHI was higher on the surface of microcapsules. Studies of water of hydration had shown that the swelling of ALG-EHG-CHI microcapsules was lower. Then the usage of EHG helps to enhance the controlled release.In imitated gastric and intestinal juice, the experiment of BSA release from ALG-EHG-CHI microcapsules indicated that the release rate become slowly with suitably decreasing the molecular weight of KGM and the concentration of gel ions. Raising the concentration of CHI and that of KGM and the molecular weight of CHI also enhance the controlled-release. The better system was 2% ALG and 0.5% EHG of 5min and 0.5% CHI of 1.4110×106 molecular weight. The experiment of nimodipine release from ALG-EHG-CHI microcapsules also demonstrated that proper decrease in the molecular weight of KGM would help to induce the release rate.