| Layered double hydroxides (LDHs), consisting of two or more kinds of divalent and trivalent metal ions with layered crystal structure, are a class of layered materials in which the crystal layers are positively charged and the anions of interlayer can be exchanged. LDHs nanohybrids have been widely applied in various aspects such as adsorption, catalyst, waste water treatment, drug carrier, and so on. The interlayer region of LDHs may be considered as a microvessel, so that some drug molecules may be intercalated into the gallery of LDHs to form drug-LDHs nanohybrids. Based on the electrostatic interaction, hydrogen bond interaction, Van der Waals force and steric hindrance effect, the drug-LDHs nanohybrids can prohibit the release of drug moleculars from the interlayer. Therefore, the drug-LDHs nanohybrids have a significant potential in the controlled releases.In this paper, Mg-Al LDHs was chosen as host material and some anticancer drugs, floxuridine, chlorambucil (CHL) and letrozole as guest species, were successfully intercalated into LDHs using different methods to obtain a series of drug-LDHs nanohybrids. The properties of nanohybrids were characterized by XRD, FT-IR, TEM and so on. The drug release behavior and mechanism from the nanohybrids were investigated by the kinetic strategy, as well as the relationship between the drug release and the LDHs structure.The main contents of this paper are as follows.(1) The intercalation of floxuridine into LDHs was carried out using coprecipitation method to obtain floxuridine-LDHs nanohybrids. According to the gallery height of floxuridine-LDHs and size of floxuridine molecule, two possible arrangement states of floxuridine molecules in the gallery of LDHs should be related to the loading amount: bilayer arrangement at low loading amount, and multilayer arrangements at high loading amount. The release kinetics of floxuridine from the nanohybrids was investigated at pH 4.8 and 7.2, respectively. It was found that the in vitro drug release from the nanohybrids was remarkably lower than that from the corresponding physical mixture. The release rate of floxuridine decreased according to the increase of drug loading amount and the whole release process may fit to the pseudo-second-order release kinetics.(2) CHL-LDHs nanohybrids were prepared by anion exchanging and were characterized by XRD and FT-IR. The adsorption of CHL on LDHs and some influecences to the adsorption, such as solid/liquid ratio (LDHs concentration), initial concentrations were investigated. It was found that the adsorption kinetics and isotherms was well fitted to the pseudo-second order kinetic equation and Langmiur isotherms equation, respectively. With the increase of LDHs concentration and temperature, the constant of the pseudo-second order kinetics equation and the initial adsorption rate both increase. The adsorption capacity will decrease with the increase of solid/liquid ratio. The activation energy in the adorption was calculated about 6.7 kJ/mol by Arrhenius equation.(3) Letrozole-SDS-LDHs nanohybrids were prepared by a two-step assemblage method. The loaded letrozole in the nanohybrids was up to 10.10% in weight. The release kinetics of letrozole from the nanohybrids was investigated at pH 4.8 and 7.2 buffer solutions, respectively. The drug release behavior was similar to that of the floxuridine-LDHs nanohybrids. Therefore, the nanohybrids could control the release of letrozole, and the drug-nanohybrids could be considered as a potential drug-delivery system.(4) The magneitc particles were assembled in Mg-A1 hydrotalcites with different ratio. The obtained magnetic LDHs were well dispersed, and the magnetic increases as the content of Fe element increases. Furthermore, the tegafur-LDHs magneitc nanhybrids with 53.30% loading amount by reconstruction method were successfully synthesized, which supplies the basic materials for the magnetically targeted drug-delivery system.
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