Alginate microspheres incorporating poly(hydroxyethyl acrylate-co-coumaryl acrylate-co-2-ethylhexyl acrylate) : Effect of temperature and UV irradiation on FITC-dextran release

−Alginate microspheres incorporating poly(hydroxyethyl acrylate-co-coumaryl acrylate-co-2-ethylhexyl acrylate) (P(HEA-CA-EHA)) were prepared using the water droplets of W/O emulsion as a template. P(HEA-CAEHA) was prepared by a free radical reaction and the HEA/CA/EHA molar ratio was calculated to be 96.1 : 2.0 : 1.9 on the 1H NMR spectrum. The copolymer exhibited a lower critical solution temperature around 27 oC in distilled water. The microspheres were prepared by using O/W emulsion as a template and Ca2+ as a cross-linker for alginate. The resulting microspheres were subjected to UV (365 nm) irradiation for the cross-linkage of P(HEA-CA-EHA). The irradiation of UV (254 nm) to the UV (365 nm)-treated microsphere promoted the release of FITC-dextran (MW. 4,000), possibly due to the cleavage of the CA residue dimers. However, the temperature change had little effect on the release degree in the range of 21 oC to 37 oC.