pH-triggerable and ultraviolet-triggerable β-cyclodextrin microgel

초록

beta-Cyclodextrin (beta CD) microgels were prepared water in oil emulsion, and cinnamic acid (CA) was loaded in the microgel by inclusion complexation. The specific loading of CA in the microgel was 0.0203mg/mg, and it was less than that the calculated specific loading (0.0368mg/mg). The maximum swelling ratio of CA-loaded beta CD microgel (CA beta CD microgel) decreased from 233.9% to 225.7% upon the irradiation of ultraviolet light (lambda = 365nm). And the 5(6)-carboxyfluorescein release of CA beta CD microgel, observed for 12 h, was suppressed upon the irradiation of ultraviolet light, possibly because the microgel can be photocross-linked, and its mass transfer resistance against dye diffusion would increase. The swelling ratio of CA beta CD microgel somewhat depended on the pH value of the medium, possibly because electrostatic repulsion can be developed within the microgel by the ionizable carboxylic group of CA. The 5(6)-carboxyfluorescein release degree in 12 h of CA beta CD microgel increased from 10.5% to 85.1% when the pH value increased from 3.0 to pH 9.0. This is mainly because CA is more soluble at a higher pH value. In the full range of pH value tested, the release degrees of CA beta CD microgel were slightly higher than those of beta CD microgel, possibly because of the electrostatic repulsion developed within the CA beta CD microgel. Copyright (C) 2014 John Wiley & Sons, Ltd.

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