Nanogels Composed of Cinnamoyl Alginate and Cinnamoyl Pluronic F127

Abstract

Temperature-responsive nanogels were developed by photo crosslinking cinnamoyl alginate (CinAlg) and cinnamoyl Pluronic F127 (CinPlu). On the 1H NMR spectrum of CinAlg, one molecule of cinnamoyl group was calculated to be attached to every 7.7 units of the pyranose of alginate. On the 1H NMR spectrum of CinPlu, the molar ratio of Pluronic F127 to cinnamoyl group was calculated to be about 1:1.1. The air/water interfacial tension of CinAlg/CinPlu mixture solution was much lower than that of CinPlu solution and that of CinAlg solution, possibly due to their hydrophobic complexation. The nanogels were sphere-like particles on TEM photos. The mean diameter of the nanogel, determined by a dynamic light scattering technique, increased from 106 nm to 177 nm at room temperature when a UV light (365 nm, 400 W) was irradiated to the suspension for 60 minutes, possibly due to interparticle crosslinkage. It decreased with increasing temperature possibly because of the heat-induced condensation of Pluronic F127 chains. The absolute value of the negative zeta potential decreased with increasing the irradiation time, possibly due to the photo-induced condensation of alginate chains. And, it increased with increasing the temperature possibly due to the heat-induced condensation of Pluronic F127 chains.