Supramolecular gels of poly-α-cyclodextrin and PEO-based copolymers for controlled drug release

• Water-soluble, high molecular weight poly-αCDs was synthesized.
• 3D poly(pseudo)rotaxanes occurred by mixing poly-αCD with a PEO-based polymer.
• Supramolecular assemblies led to cytocompatible syringeable gels.
• Supramolecular gels sustained the release of antimicrobial drug for several days.

The aim of this work was to prepare syringeable supramolecular gels of α-cyclodextrin-polymer (poly-αCD) with various poly(ethylene oxide) (PEO)-based copolymers, which can be suitable to form depots for controlled drug release. A series of water-soluble poly-αCDs was synthesized from αCD by crosslinking with epichlorohydrin in alkaline medium. The chemical composition of the polymers was characterized by NMR (αCD content > 53%) and the molecular weight was evaluated using static light scattering (SLS). Supramolecular assemblies occurred by mixing poly-αCD (20–40% w/v) with a PEO-based polymer (i.e., PEG, Pluronic® F127 or Tetronic® 908) (10–15% w/v). Phase separation was observed and the αCD content in each phase was determined by means of the phenol–sulfuric acid colorimetric method. Formation of poly-αCD/PEO-based polymer 3D-supramolecular complexes was confirmed by diffusion-ordered NMR spectroscopy (DOSY) and X-ray diffractometry. The supramolecular assemblies showed good cytocompatibility against SAOS-2 cells and in the HET-CAM test. The supramolecular gels were able to sustain the release of vancomycin for at least 5 days at 37 °C, more efficiently than dispersions of each polymer component in separate. These results open new possibilities in the design of novel controlled delivery systems for the treatment of bone infections.

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