Cellular uptake and gene delivery using layered double hydroxide nanoparticles.

The cellular uptake of narrowly dispersed LDH {[Mg3Al(OH)8](CO3)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 µg ml-1. DNA modified 20 nm LDH nanoparticles are successful in transfection of the pEGFP-N1 DNA plasmid to NSC 34 cells.

Synthesis and antimicrobial activity of ZnTi-layered double hydroxide nanosheets.

Narrow size dispersion ZnTi-layered double hydroxide (LDH) nanosheets with lateral dimensions in the range 40-80 nm have been synthesised using a reverse microemulsion method. Electron Spin Resonance (ESR) and X-ray photoelectron spectroscopy (XPS) measurements reveal that Ti3+ sites are generated within these nanosized LDH platelets. The data show that the concentration of Ti3+ cations in the nanoplatelets is size-dependent, the 40 nm nanoplatelets have a bandgap of ca. 2.3 eV. The combination of photochemcially activity and nanoparticle size results in materials that exhibit high antipathogen activity under visible light. The biocidal efficacies of the LDHs have been investigated under visible light. The ZnTi-LDHs display size-dependent cytotoxicity against S. cerevisiae, S. aureus and E. coli in culture. The 40 nm ZnTi-LDH nanoplatelets (ZnTi-LDH-RM1) are the most potent resulting in 95% cell death. These nanoplatelets are more active compared to a conventionally prepared ZnTi-LDH or the nanoparticulate metal oxides WO3 and TiO2 (P25). The nanosized ZnTi-LDHs severely inhibit the growth of S. cerevisiae, S. aureus and E. coli in culture.