A hierarchical CoCo layered double hydroxide (LDH) nanostructure was constructed through a facile topochemical transformation route under a dynamic oxygen atmosphere. Self-assembled coral-like CoAl LDH nanostructures via the homogeneous precipitation method were also inspected under different ammonia-releasing reagents and solvents. Benzene and toluene were chosen as probe molecules to evaluate their catalytic performance over the metal oxide CoCoO and CoAlO calcined from their corresponding LDH precursors. Nanocatalyst of trivalent Co ions replaced Al(3+) ions in the bruited-like layer had a higher catalytic activity (T99(benzene) = 210 °C and T99(toluene) = 220 °C at a space velocity = 60 000 mL g(-1) h(-1)). Raman spectroscopy, XPS and H2-TPR demonstrated the existence of abundant high valence Co ions that serve as active sites. TPD verified the types of active oxygen species and surface acid properties. It was concluded that the high valence Co ions induced excellent low-temperature reducibility. Surface Lewis acid sites and the surface Oads/Olatt molar ratio (0.61) played relevant roles in determining its catalytic oxidation performance. Our design in this work provides a promising approach for the development of nanocatalysts with exposed desirable defects.

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The cellular uptake of narrowly dispersed LDH {[Mg 3 Al(OH) 8 ](CO 3 ) 0.5 } nanoparticles into the Mouse Motor Neuron (NSC 34) cell line has been studied. The effect of LDH concentration and incubation time on the cellular uptake was investigated using fluorescein isothiocyanate (FITC) labelled LDH nanoparticles. We observed that cellular uptake increases with the increased LDHs concentration and incubation time.Confocal laser microscopy and transmission electron microscopy reveal that 20 nm LDHs nanoparticles intrude into the cytoplasm and then enrich in the cellular nucleus, while nanoparticles greater than 20 nm only locate in the cytoplasm. The 20 nm sized LDHs nanoparticles display similar uptake to both the cytoplasm and nucleus, and show little cytotoxicity with no significant decrease in NSC 34 cell proliferation and viability below 200 mg ml À1 . DNA modified 20 nm LDH nanoparticles are successful in transfection of the pEGFP-N1 DNA plasmid to NSC 34 cells.

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