Cyclodextrin-based device coatings for affinity-based release of antibiotics

Cyclodextrin-based hydrogels were synthesized to create robust networks with tunable mechanical properties capable of serving as device coatings. The CD networks were able to swell and load drug in aqueous and organic solvents. The rheological properties of the swollen gels were investigated using stress and frequency sweeps, with both demonstrating high storage modulus, indicating strong elastic gels. The ability of the gels to swell in numerous solvents allowed for the separate loading and release of different antibiotic drug molecules with varying hydrophilicities. Based on FTIR and TGA studies, each drug was found to form an inclusion complex with CD. For comparison, dextran gels were prepared similarly. As expected for affinity-based mechanisms, the release of drugs from the CD-based gels was slower than diffusion-based release from the dextran gels, and could be sustained for more than 200 h. Coating potential was tested by coating two different medical devices: metal screws and polymer meshes. The meshes were characterized by SEM, revealing that CD-based coatings resulted in a uniform thin film, whereas the dextran gels only partly coated the device and showed delamination. Considerably longer bactericidal activity against Staphylococcus aureus was observed for both the CD hydrogels and coatings, as compared to dextran-based ones. The slow, sustained, affinity-based release of antibiotics from the CD-based networks reflects their potential as a delivery platform.