Preparation and characterization of a ternary inclusion complex comprising the norfloxacin/β-cyclodextrin complex incorporated in a liposome

A liposome containing the β-cyclodextrin (β-CD) complex of norfloxacin (NFLX) was prepared and its ternary structure characterized. Structural information about the NFLX/β-CD complex was obtained by infrared spectroscopy and powder X-ray diffraction. Nuclear magnetic resonance (NMR) ROESY experimental results confirmed the inclusion structure, with the results well matching those of molecular docking studies. The stoichiometry and the association constant of the complex were also determined. Free multilamellar vesicles composed of soybean phospholipids and cholesterol as membrane materials were prepared and loaded with NFLX, β-CD, and the NFLX/β-CD complex. Diffusion coefficients measured by 19 F NMR spectroscopy were compared. In addition, saturation transfer difference NMR experiments were performed to elucidate the structural differences of these liposomes. The results confirmed the formation of the ternary inclusion system comprising the liposome and the NFLX/β-CD complex. Transmission electron micrographs showed the morphological features and particle size differences of these liposomes.