Investigation On The Preparation And Application Of PH/Temperature-Sensitive Sodium Alginate/Poly(N-Isopropylacryla-Mide) Hydrogels Microcapsulation

Environment-sensitive hydrogel is one kind of intelligent hydrogels. Considerable research attention has been focused on this because they have great applications, e.g. drug delivery, biomaterials separation and enzyme immobilization. Especially, pH and temperature sensitive hydrogels get the most attention. In this paper, the natural material sodium alginate (Al) which is pH-sensitivity and poly(N-isopropylacrylamide) (PNIPAM) which is the excellent tempera-ture sensitivity were chosen to make hydrogels microcapsules. High-voltage electrostatic droplet generator method was used to prepare sodium alginate microcapsule. The results showed that the prepared microcapsules have smooth surface with average particle size about 100 micro-meters. The effect of the microcapsules structure and the swelling and deswelling properties were systematically investigated. In addition, choose 5-fluorouracil (5-Fu) as drug model to study the drug delivery of microcapsules.1.Al/PNIPAM microcapsules was prepared through high-voltage electrostatic droplet generator. The swelling behaviors of microcapsules in detail was studies. The experimental results showed that at pH 1.2 buffer solution the swelling ratios of the Al/PNIPAM semi-inter-penetrating network (IPN) are lawer than the pure PNIPAM hydrogel. When the content of Al raised. At pH 7.4 buffer solution, the result is opposite. At both the acidic condition and weak alkaline condition, the swelling ratios of the microcapsules decrease when the temperature increase. The pH influence on the microcapsules swelling ratios is that when ambient temperature below the lower critical solution temperature (LCST) 25℃the pH-response is more significant than that of above the LCST 37℃.2.The results of the swelling and deswelling of microcapsules indicated that the swelling rate increased with the Al content increasing at 25℃and weak alkaline condition. The effect of pH value on the swelling rate was dependent on temperature. The deswelling of microcapsules was the same.3.Stduying on drug delivery of microcapsules found out that at 37℃and analogue gastric juice buffer solution(pH=1.2) the release rate is below than that at 25℃and analogue intestinal juice buffer solution(pH=7.4). The release rate increase with the increase Al content of microcapsules. This means the Al/PNIPAM microcapsules could be used as the oral deliver of 5-Fu.