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-CA-EHA) 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 °C 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 °C to 37 °C.