Abstract: A new drug-inorganic composite involving an antibiotic compound norfloxacin(Nor) intercalated Mg-Al layered double hydroxides(Nor-LDHs) was assembled with coprecipitation and ion-exchange methods. The samples thereby obtained were characterized via XRD, FTIR, UV-Vis, TG-DTA and ICP measurements. The results show that the original interlayer nitrate anions of the hydrotalcite can be replaced by norfloxacin anions, and norfloxacin intercalated Mg-Al layered double hydroxides were obtained with a good crystallinity. XRD analyses indicates that the interlayer spaces of as-synthesized Nor-LDHs were 1.29 nm to 1.33 nm, and compared with three-dimensional molecular size of Nor ion calculated from the PM3 semi-empirical molecular orbital method. The norfloxacin guests were arranged alternately with monolayer vertical(along the short axis orientation) between layers. It is found that the interaction of the host layers and the guests is through hydrogen bonding and electrostatic attraction, confirming that the intercalated hydrotalcite has a supramolecular structure. The thermal stability, acid resistance and sustained-release of norfloxacin anion-pillared hydrotalcite were enhanced to a considerable extent, comparing with that of norfloxacin. The release profiles were fitted by Bhaskar equation and the first-order equation, the fitting data primarily follow the experimental results.

Key words: Layered double hydroxides, Layered double hydroxides, Norfloxacin, Norfloxacin, Drug-inorganic composite, Drug-inorganic composite, Thermal stability, Thermal stability, Sustained-release, Sustained-release