Cyclosophoraose/cellulose hydrogels as an efficient delivery system for galangin, a hydrophobic antibacterial drug

Highly water-soluble cyclosophoraose (Cys) has been recently used as a suitable complexation agent to enhance the solubility of drugs that are hardly water-soluble by molecular encapsulation via host–guest complexation. In this study, a novel Cys/cellulose hydrogel was prepared by cross-linking Cys and cellulose for efficient galangin delivery to improve antibacterial activity. Galangin was known to directly inhibit the activity of β-lactamase and to exhibit intrinsic antibacterial activity. The inhibition of β-lactamase by galangin was also known to enhance the eradication of a strain of methicillin-resistant Staphylococcus aureus. However, efficient delivery of galangin in an aqueous solution for improved antibacterial activity could not be achieved because of its extremely poor water solubility and bioavailbility. The structure and morphology of the resulting hydrogels were verified using with various instrumental techniques using rheometer, FT-IR spectroscopy, solid-state NMR spectroscopy, XRD and FE-SEM. The loading amount of galangin increased as the Cys content in the hydrogels increased, with a release time of 48 h. The galangin loading amount and its cumulative amount released from the Cys/cellulose hydrogel were 1.62- and 1.64-fold greater than those of galangin released from cellulose hydrogel, respectively. Additionally, the galangin-loaded Cys/cellulose hydrogel had antibacterial activity against S. aureus, with growth inhibition maintained up to 72 h. Furthermore, the Cys/cellulose hydrogel did not show any cytotoxicity toward human dermal fibroblasts. Throughout the study, the Cys/cellulose hydrogel demonstrated potential advantages as an efficient antibacterial dressing material for galangin delivery through targeting of drugs to the wound site in a sustained manner over a long period without frequent dressing changes.