Release Property of Alginate Beads Coated with Poly(N-isopropylacrylamide-co-dimethylaminoethylmethacrylate)

Abstract

Alginate beads were coated with copolymers of N-isopropylacrylamide and dimethylaminoethylmethacrylate (P(NIPAM-co-DMAEMA)s) by taking advantage of electrostatic interaction between alginate and the copolymer. The copolymers, of which DMAEMA contents in the feed for the copolymerization were 5.0% (PND 5) and 15.0% (PND 15), were employed for the coatings of alginate beads. The adsorption curve of PND 5 and PND 15 on the surface of alginate beads seemed to be Langmuir isotherm. The beads were coated in the PND solutions (2%, pH 5.0 or pH 7.0) and the amounts of adsorption (g PND/g alginate) were about 1.3 with PND 5 solution (pH 5.0), 1.2 with PND 15 solution (pH 5.0), and 0.75 with PND 15 (pH 7.0). The release from the beads coated with PNDs were observed at 30°C, 37°C, and 45°C using amaranth or FITC-dextran as a dye. The degrees of release were significantly suppressed due to the coating layers of PNDs. However, the coating layers could hardly act as a controller for the temperature-sensitive release.

Keywords:

• Alginate beads
• dimethylaminoethylmethacrylate
• N-isopropylacrylamide
• temperature-sensitive release

This work was supported by a grant (KRF-2007-314-C00271) from Korea Research Foundation, Republic of Korea.