Biological evaluation of layered double hydroxides as efficient drug vehicles.

Recently there has been a rapid expansion of the development of bioinorganic hybrid systems for safe drug delivery. Layered double hydroxides (LDH), a variety of available inorganic matrix, possess great promise for this purpose. In this study, an oxidative stress biomarker system, including measurement of reactive oxygen species, glutathione content, endogenous nitric oxide, carbonyl content in proteins, DNA strand breaks and DNA-protein crosslinks, was designed to evaluate the biocompatibility of different concentrations of nano-Zn/Al-LDH with a Hela cell line. The drug delivery activity of the LDH-folic-acid complex was also assessed. The resulting data clearly demonstrated that nano-LDH could be applied as a relatively safe drug vehicle with good delivery activity, but with the caveat that the effects of high dosages observed here should not be ignored when attempting to maximize therapeutic activity by increasing LDH concentration.

Self-assembly of Bi2WO6 square nanoplates into hierarchical structures.

Bi2WO6 hierarchical structures constructed by a number of square nanoplates of average approximately 70 nm in side length and approximately 25 nm in thickness have been synthesized by a hydrothermal method at 180 degrees C. The single-crystal subunit nanoplates with (002) as their two-dimensional (2D) surfaces assembled orderly using both their edges and faces into free-standing films. It was found that the self-assembled growth of these hierarchical structures strongly depended on surfactant Cetyl Trimethyl Ammonium Bromide (CTAB), the amounts of the starting materials and the molar ratio of precursors (Bi3+ to WO4(2-)), etc. The growth mechanism was discussed based on the comparative experimental results.

A novel glucose sensor based on monodispersed Ni/Al layered double hydroxide and chitosan.

A novel cheap and simple amperometric glucose biosensor, based on the electrode modified with the Ni/Al layered double hydroxide (LDH) nanoflakes and chitosan (CHT), without glucose oxidase, is presented. The glucose biosensor based on monodispersed high active Ni/Al-LDH nanoflakes and CHT exhibits an appropriate linear range of 0.01-10mM and good operational stability. The amperometric sensor shows a rapid response at the potential value 0.48V. In addition, optimization of the biosensor construction, the effects of the applied potential, the scan rate as well as common interfering compounds on the amperometric response and human serum samples analysis of the sensor were investigated and discussed.

Synthesis of hollow ZnO microspheres by an integrated autoclave and pyrolysis process.

Hollow zinc oxide microspheres have been synthesized from a micro ZnBr2·2H2O precursor obtained by an autoclave process in bromoform steam at 220 °C /2.5 MPa. Field-emission scanning electron microscropy (FE-SEM) and transmission electron microscopy (TEM) show that the products are about 1.0 µm single crystal spherical particles with hollow interiors, partly open surfaces and walls self-assembled by ZnO nanoparticles. X-ray diffraction (XRD) analysis shows that the as-prepared ZnO hollow spheres are of a hexagonal phase structure. A possible formation mechanism is suggested on the basis of the shape evolution of ZnO nanostructures observed by SEM and TEM. The room-temperature photoluminescence (PL) spectrum shows UV emission around 386 nm and weak green emission peaks indicating that there are few defects in the single crystal grains of the ZnO microspheres.