Study On The Preparation And Property Of Intelligent PVA/CS Composite Hydrogel Microsphere

This article introduces the background, theory of the gel, PVA and CS'propetrties and its application.Using PVA as the base-material, which is improved by chemical crosslinking, composited natural polymer CS, produced PVA/CS compound hydrogel microspheres. Combining chitosan's excellent biodegradability and PVA's well biocompatibility, taking advantage of the temperature sensitive and biodegradable of the CS to produce this kind of surface porous structure gel microshperes, which has suitable mechanical strength. Loading polypeptide protein drugs with this kind of spheres which can be released selectively in any condition, so that it can improve the bioavailability.The main study results show as follows:1. Using the chemical crosslinking to modify the PVA hydrogel,which can combine the hydroxyl of the PVA molecules with the aldehyde, induced a part of hydrophobic aldehyde circle into the molecular chain. For researches, the swelling properties of systems with increasing concentration of PVA decreaseing, with the increasing of acetaldehyde concentration decreaseing. Based on the environmental sensitivity testing of the gel, PVA gel is temperature sensitive but not pH sensitive.2. Condenses phase separation prepared chitosan hydrogel microspheres. The results showing as the follows, when the chitosan solution concentration is 2.0%-3.5%, sodium sulfate concentration is larger than 3.5%, which can get the best shape and intensity of chitosan hydrogel microspheres. In acid environment, the microspheres swelling hardly clearly, in alkaline environment, the microspheres showed higher expansion. By and way, chitosan hydrogel is pH sensitive. And with the changing of the pH, the result can be repeated.3. Through the chitosan solution combined with the PVA solution, the compound aqueous gel microspheres can be got from the phase separation. Study shown that PVA concentration of 5%, CS concentration of 4.5%, PVA:CS=2:1, under this condition which the aqueous gel have a good spherical property. No matter in acidic or alkaline environment, swelling degree of gel decreased with medium temperature risen, obvious it means gel is temperature sensitive. In the simulation fluid of the stomach the aqueous gel is swelling hardly obviously. In the simulation fluid of colon, the microspheres show higher expansion. It all shows that the compound aqueous gel possessed temperature and pH sensitive characteristics, which can be used as targeted drug release in the colon.4. Studied PVA/CS compound gel microsphere's delivery performance. It shows that PVA/CS compound aqueous gel microsphere has a good drug loading efficiency and well ability of drug delayed delivery. The PVA/CS aqueous gel sphere has a good expectation in the area for the drug release in the future.