Engineering small MgAl-layered double hydroxide nanoparticles for enhanced gene delivery

In this paper we report an approach for engineering small MgAl-layered double hydroxide (sLDH) nanoparticles with the Z-average diameter of about 40 nm. This method first requires co-precipitation of magnesium and aluminum nitrate solution with sodium hydroxide in methanol, followed by LDH slurry collection and re-suspension in methanol. The methanol suspension is then heated in an autoclave, followed by separation via centrifugation and thorough washing with deionized water. The nanoparticles are finally dispersed in deionized water into homogeneous aqueous suspension after 4–6 day standing at room temperature. In general, sLDH nanoparticles have the Z-average size of 35–50 nm, the number-average size of 14–30 nm and the polydispersity index (PdI) of 0.19–0.25. The prepared sLDH suspension is stable for at least 1 month when stored at fridge (2–8 °C) or ambient (22–25 °C) temperature. Moreover, sLDH nanoparticles are found to carry higher payloads of small double stranded DNA (dsDNA). More excitedly, sLDH nanoparticles transfect dsDNA into HEK 293T cells with a 5 to 6-fold greater efficiency compared to the larger LDH particles (Z-average diameter of 110 nm).