The Preparation And Characterization Of Biopolymer Hydrogels

Hydrogel is a soft material, which contain a lot of water and can be well swelled in water. Biopolymers are polymers coming from nature. Biopolymer hydrogel has the characteristics of both biopolymers and hydrogel which result in its good biocompatibility and biodegradability. The advances of biopolymer hydrogels make it very popular in bio-engineering applications. However, the mechanical property of biopolymer hydrogel is a big barrier for its development. In this paper, interpenetrating polymer networks (IPN) were made to improve the strength of biopolymer hydrogel.Firstly, a highly expandable and tough microcapsule was prepared by water-in-oil emulsion polymerization. Because of the three network was formed, the volume of the microcapsule could be expanded to about 4.2×105times larger than the original size without breakage. When the microcapsule was used as a molecule vector, it showed excellent pH sensitive molecule protection and release profiles. The molecule release driven by acid at pHl.2 showed the similar profile as the gas-formation-based drug delivery system. Besides, this microcapsule showed pH sensitive molecules protection and release profiles. These characteristics of microcapsules might be used in fields that need expandable materials to offer protection or pH sensitive controlled release of some molecules for therapy.Secondly, a chitosan-alginate porous hydrogel had been made by foaming method. Three networks formed IPN, which made porous hydrogel tough. The foaming method made a lot of porous in the hydrogel structure. Besides, the porous hydrogel had both the similar swelling ability in widely pH and suitable biodegradability. These characteristics are big advantages for the use in bio-engineering.Finally, a DNA hydrogel had been prepared using DNA and temperature responsive N-isopropyl acrylamide (NIPAAm). The most important characteristic of this DNA hydrogel was its preparation method. This method made it easier to make a DNA hydrogel using a concentration just 0.91% times of DNA used before. That was resulted by the IPN synthesized in this process. The influence of DNA to the low critical solution temperature (LCST) and cloud point shared the same regular with previous researchs.Three kinds of biopolymer hydrogels had been synthesized in this paper and the properties of these three hydrogels had been characterized. The formation of interpenetrated networks made great contribution to the increasing of the strength of hydrogels and resulted lower concentration of DNA that needed in DNA hydrogel.