A polyrotaxane gel using boronic acid-appended γ-cyclodextrin as a hybrid cross-linker

Abstract

A boronic acid-appended γ-cyclodextrin (BA-CyD) was synthesized as a hybrid cross-linker of polyvinyl alcohol (PVA) to form a new type of hydrogel. The CyD moiety of BA-CyD forms an inclusion complex with the PVA chain to produce a mechanically interlocking structure. At the same time, the BA moiety of BA-CyD forms covalent bonds with the 1,3-diol moieties of PVA. On the basis of these two modes of interaction, the hybrid cross-linker connects two PVA chains, thus resulting in the formation of a hydrogel. To investigate the possibility of this hydrogel becoming the basis for an intelligent material for drug delivery, sugar-responsive drug release from the hydrogel was demonstrated.

Continuous flow synthesis of 6-monoamino-6-monodeoxy-β-cyclodextrin

“…Substitution of the p-toluenesulfonyl group of Ts-β-CD (2) by azide can be carried out in water [40,41], DMF [14,42], or in their combination [43,44] at elevated temperatures. Water is preferred over DMF due to its lower cost and non-toxicity.…”

Cross‐Linking Building Blocks Using a “Boronate Bridge” to Build Functional Hybrid Materials

“…Uchida et al. developed a dynamic gel cross‐linked by both mechanical interlocking and dynamic covalent bonds composed of polyrotaxane consisting of a poly(vinyl alcohol) main chain and γ‐cyclodextrin modified with PBA moieties . The resultant turbid hydrogel showed a competitive diol compound‐responsive turbidity change over time, and release of fluorescent molecules entrapped inside the gel.…”

Mono-6-Substituted Cyclodextrins—Synthesis and Applications

“…Only one article describing the preparation of γ-CD derivatives from N 3 -γ-CD by CuAAC can be found. Uchida et al [ 147 ] synthesized boronic acid-appended γ-CD as a cross-linker of polyvinyl alcohol chains to form a hydrogel. This γ-CD derivative was formed by the reaction of N 3 -γ-CD with propargyl ester of 4-borono-benzoic acid.…”