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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.

Nanoplatelet Co−Al layered double hydroxides (LDHs) {Co1.8Al1.1(OH)6(DDS) x ·yH2O (DDS = dodecyl sulfate; x ≈ 0.9; y = 2−6)} have been prepared using a homogeneous precipitation approach in water pools formed by a water-in-oil reverse microemulsion. The size of the LDH particles is controlled by adjusting the water to surfactant ratio (ω). The particle sizes vary from about 60 × 60 × 13 nm3 to 160 × 160 × 40 nm3 with increasing ω. This contrasts with platelets of Co1.89Al(OH)6(DDS)0.8·4.3H2O prepared by conventional homogeneous precipitation which had dimensions about 2−3 μm wide and 0.5−1 μm thick. All the Co−Al LDH samples were paramagnetic above 50 K. The molar magnetic susceptibilities of each sample were very similar and they could all be fitted to the Curie−Weiss law with μeff ca. 5.2 μB per Co2+ and θ ca. 6 K. Below 50 K, we observed a rapid rise in χM T indicative of cooperative ferromagnetic interactions. At very low temperature the LDH nanoplatelets show magnetic behavior which is different to Co1.8Al1.1(OH)6(DDS)x·yH2O made by conventional homogeneous precipitation. The nanoplatelets show bifurcation in their field-cooled (FC) and zero-field-cooled (ZFC) magnetizations and also a frequency dependence of the in-phase (χ′) and out-of-phase (χ′′) ac susceptibilities, which is dependent on the size of the nanoplatelets.

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