3D graphene oxide supramolecular hybrid hydrogel with well-ordered interior microstructure prepared by a host-guest inclusion-induced self-assembly strategy

Here we report a novel strategy for constructing supramolecular hybrid hydrogels with regular porous structure via three-dimensional self-assembly of graphene oxide (GO) and rigid pseudopolyrotaxane (PPR) formed by pi-pi linear poly(ethylene glycol) (PEG) threading a series of alpha-cyclodextrin (alpha-CD). By the strong p-p interactions between the pyrene group (Py) and GO sheets, the pyrene-poly(ethylene glycol) (Py-PEG) conjugate polymer was successfully adsorbed onto the surface of GO, forming the homogenous layered GO-Py-PEG aggregates induced by parallel arrangement of GO sheets. Subsequently, alpha-CD was added into GO-Py-PEG hybrids solution, and rigid necklace-like PPR supramolecular structure was formed owing to the PEG chains threading into the cavities of a series of alpha-CD via the well-known host-guest inclusion interaction. Soon afterwards, 3D supramolecular hydrogel with well-ordered porous structure was formed by virtue of the 3D self-assembly of GO-Py-PEG sheets induced by the strong hydrogen-bond interaction among adjacent rigid PPR. GO-Py-PEG/alpha-CD hydrogel shows enhanced mechanical property compared with native Py-PEG/alpha-CD hydrogel and also retains the shear-thinning property. The hybrid hydrogel was further utilized for loading water-soluble drug doxorubicin (DOX), and subsequently the microstructure-dependent drug delivery performance was investigated preliminarily. We believe this study will provide a new insight for designing and constructing supramolecular hydrogels to broaden their breakthrough applications.