Preparation And Medicine Release Study Of Chitosan/PVA Composite Hydrogel

In the first part of this paper, it developed one kind of cataplasm made by chitosan /poly(vinyl alcohol) blend hydrogel. By the use of orthogonal experimental design, the best proportion of this system and conditions during the preparation were confirmed. The holding power, tack, peel strength, remnant and penetration of the cataplasm were considered as the judgment guideline at the same time. And then the best proportion and conditions were confirmed. It was revealed that the best proportion was PVA 1.00 g, CS 0.25 g, glutaraldehyde (2%) 0.28 ml and water 16 ml. It was considered completely that the best conditions was stiring at 65℃for 15 min and crossing for 15 min. In addition, the curve of lost weight rate as time was observed. It was showed that the content of water in the hydyogel was approximately 56%. At the meaning time, the Fourier transform infrared spectroscopy of the hydrogel was showed that glutaraldehyde was mainly reacted with chitosan not poly(vinyl alcohol). The second part of this paper mainly studies the preparation precess of CS/PVA therm-sensitive hydrogel and the characters of loading and release of drugs, which particularly includes research on the effects of polymer concentration, ratio of PVA to CS, temperature and pH on the gelation time of CS/PVA system, and the loading characters of CS/PVA composite hydrogel with different ratio of CS to PVA in various pH media, and the effects of loading process, the medicine loaded, pH and so on on the release process. The results of experiments show that when the ratio of CS to PVA is constant, the gelation time becomes shorter as the polymer concentration grows; when the polymer concentration is constant, the gelation time becomes shorter as the proportion of CS grows; the gelation time becomes shorter as the temperature is higher; the gelation time becomes shorter as the pH grows; the loading speed becomes faster as the proportion of PVA decreases; in acidic and neutral media, the loading characters of CS/PVA system are similar: there is a big load at first, then some medicine goes back to the media and then the load grows bigger gradually, but after some time there is a huge growth of the loading amount because the structure of the gel becomes loose after soaking for a long time, but in alkaline media such phenomenum does not happen; the release speed becomes slower as the proportion of PVA grows and the pH grows which is in accordance with the law of swelling; adding medicine in the gel could affects its 3-D structure making it more loose, so the medicine can be released easily; different medicines loaded have different release characters; the release time can be extended by crosslinking the CS/PVA system with crosslinker making the structure of the gel more close and embedding the medicine intoβ-Cyclodextrin solution before joining the hydrogel.