Supramolecular hydrogels of α-cyclodextrin/reverse poloxamines/carbon-based nanomaterials and its multi-functional application

Supramolecular hydrogels were prepared using a-cyclodextrin (alpha-CD) and a poloxamine (reverse Tetronic 90R4, T90R4) which has four diblock arms with a poly(propylene oxide)-poly(ethylene oxide) (PPO-PEO) structure. The alpha-CD can slide past the PPO blocks and towards the middle PEO blocks owing to the unsuitable energy between alpha-CD and PPO to form alpha-CD/T90R4 inclusion complexes (ICs). The incorporation of graphene oxide (GO) into alpha-CD/T90R4 ICs changes their phase behavior and forms mechanically strong hydrogels because of the hydrogen-bonding between the GO nanosheets and the alpha-CD and PEO blocks of T90R4. The native hydrogel, as well as the alpha-CD/T90R4/GO hybrid hydrogels, have been thoroughly characterized by using various microscopy techniques. Field emission scanning electron microscopy (FE-SEM) was used to observe the morphology of the hydrogel, and differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to evaluate the thermal stability of the hydrogel. Fourier transform infrared (FT-IR) spectroscopy and X-ray diffraction (XRD) were used to characterize the interactions within the supramolecular assemblies and the degree of crystallinity of the xerogels, respectively. The experimental results demonstrated that alpha-CD/T90R4/GO hybrid hydrogels could adsorb various dyes selectively, and that it is a promising candidate for sewage treatment, while the native one cannot adsorb the dyes well. Moreover, the native alpha-CD/T90R4 hydrogel has excellent biocompatibility, and the results of the in vitro drug release study showed that the injectable doxorubicin (DOX)-loaded hydrogel is appropriate for the controlled release of anticancer drugs, while the alpha-CD/T90R4/GO hybrid hydrogels can reduce the release rate of DOX.