Cyclodextrin/poly(ethylene glycol) polypseudorotaxane hydrogels as a promising sustained-release system for lysozyme

In this study, to clarify the utility of polypseudorotaxane (PPRX) hydrogels composed of poly(ethylene glycol) (PEG) and α- or γ-cyclodextrin (α- or γ-CyD) as a sustained-release system for protein drugs, we prepared CyD PPRX hydrogels including lysozyme, and then the release profiles of lysozyme from these hydrogels and the release mechanisms were investigated. The α- and γ-CyD formed PPRX hydrogels by threading onto one PEG chain and two PEG chains, respectively. The formation of α- and γ-CyD PPRX hydrogels including lysozyme was based on physical cross-linking arisen from their columnar structures. The in vitro release rates of lysozyme were markedly decreased by the encapsulation into CyD PPRX hydrogels. In addition, when release data were plotted according to Korsmeyer-Peppas model, the exponent values (n) in the α- and γ-CyD systems had no statistically significant difference, suggesting that these release mechanisms were almost same. In conclusion, these results suggest that α- and γ-CyD PPRX hydrogels possess the potential as a sustained-release system for lysozyme.