Polyol-responsive pseudopolyrotaxanes based on phenylboronic acid-modified polyethylene glycol and cyclodextrins

Abstract

Phenylboronic acid (PBA), which reacts with polyols to form cyclic esters, was attached to the amino terminal of polyethylene glycol (PEG) via amide bonds. PBA-PEG was used to prepare pseudopolyrotaxanes (pPRXs) by combining it with cyclodextrins (CyDs). In the case of α-CyD, a single stranded pPRX formed that disintegrated in the presence of catechol (CA), D-fructose (Fru), and D-glucose (Glc). The order of response was CA > Fru > Glc, which corresponds with the affinities between the PBA moiety and the polyols. In contrast, a pPRX using γ-CyD, which has a double-stranded structure, showed sugar-induced disintegration but did not show a response to CA.We explained these apparently curious responses of the pPRXs using a mechanism based on the penetrability of the polyol-bound PBA toward the cavities of the CyDs. The pPRXs, which are a class of molecular machine, show two selectivities; one is derived from polyol selectivity, and the other is based on the penetrability for CyDs.

Sugar-responsive smart materials based on phenylboronic acid and cyclodextrin

“…A smart material that responds to a chemical stimulus of sugar could find application as an ideal insulin formulation. Using phenylboronic acid (PBA) as a sugar-sensing moiety and cyclodextrin (CyD) as a basic skeleton of smart materials, we have been developing sugar-responsive smart materials for an artificial pancreas [9][10][11][12][13][14].…”