Synthesis, properties and controlled release behaviors of hydrogel networks using cyclodextrin as pendant groups

Based on inclusion character of β-cyclodextrin (β-CD) with drug molecule and low glass transition temperature of poly(2-hydroxyethyl acrylate) (PHEA), a series of hydrogels with different compositions were synthesized by the copolymerization of a monovinyl cyclodexrin monomer with 2-hydroxyethyl acrylate (HEA). The structure and properties of the hydrogels were characterized by FTIR, DSC, TGA and swelling measurements. It is found that swelling ratios of these β-CD hydrogels can keep a relative stability in the range of pH from 1.4 to 7.4, and are not sensitive to change in NaCl concentration. Using drug N-acety-5-methoxytryptamine (melatonin, MEL) as a model molecule, the controlled drug release behaviors of these hydrogels were investigated. The results indicate that the diffusion and permeation of MEL from the hydrogels may be a dominant factor for its release. Owing to the formation of MEL/β-CD retarding diffusion rate of MEL, a sustained release of MEL from hydrogel with high content of β-CD can be obtained compared with hydrogel PHEA without β-CD.