Direct synthesis of layered double hydroxide nanosheets for efficient siRNA delivery

In this paper, we have developed a simple yet efficient method to prepare stable single-sheet MgAl-layered double hydroxide (MA-NS) suspensions without using organic solvents or surfactants. This green approach involves a fast co-precipitation with hydrothermal treatment. The average hydrodynamic diameter of mono-disperse fully-delaminated LDH nanosheets can be precisely tailored in the range of 25-300 nm. The reproducibility of making identical suspensions under identical conditions has been confirmed and the method has also been successfully applied to prepare stable and single-layered LDH nanosheet suspensions containing various transition metal ions such as Ni2+, Fe2+, Fe3+ and Co2+ in the single hydroxide layer. MgAl-LDH nanosheets (MA-NSs) with various sizes do not exhibit any acute cytotoxicity at concentrations up to 400 mu g mL(-1) as assayed by MTT. The cellular uptake and cell viability data have demonstrated MA-NSs can efficiently load and deliver small interfering RNA (siRNA) into osteosarcoma (U2OS) cancer cells, and significantly inhibit their growth. Thus, MA-NSs have great potential as an effective cellular delivery system for siRNA therapy, in addition to their conventional applications in coatings, catalysis, composites and adsorption.