Branched polyrotaxane hydrogels consisting of alpha-cyclodextrin and low-molecular-weight four-arm polyethylene glycol and the utility of their thixotropic property for controlled drug release

In this work, we developed a new class of branched polyrotaxane hydrogel made of 4-arm polyethylene glycol (4-PEG) and alpha-cyclodextrin (alpha-CD) using supramolecular host-guest interactions as a cross-linking strategy. Because of the dynamic nature of the non-covalent host-guest cross-linking, the resulting supramolecular alpha-CD/4-PEG hydrogels show thixotropic behavior and undergo a reversible gel-sol transition in response to shear stress change. We loaded the antiglaucoma drug brimonidine into the alpha-CD/4-PEG gel and found the drug release kinetics was controlled by shear stress. This thixotropic shear thinning property makes the supramolecular hydrogels highly attractive in drug delivery applications and suitable for preparation of injectable drug formulations. (C) 2018 Elsevier B.V. All rights reserved.