Nanodiamond as a vector for siRNA delivery to Ewing sarcoma cells

The ability of diamond nanoparticles (nanodiamonds, NDs) to deliver small interfering RNA (siRNA) into Ewing sarcoma cells is investigated with a view to the possibility of in-vivo anticancer nucleic-acid drug delivery. siRNA is adsorbed onto NDs that are coated with cationic polymer. Cell uptake of NDs is demonstrated by taking advantage of the NDs' intrinsic fluorescence from embedded color-center defects. Cell toxicity of these coated NDs is shown to be low. Consistent with the internalization efficacy, a specific inhibition of EWS/Fli-1 gene expression is shown at the mRNA and protein level by the ND-vectorized siRNA in a serum-containing medium. Embedded color-center defects are used to monitor intrinsic nanodiamond (ND) fluorescence less than 24 h after the release of their FITC-labeled small interfering RNA (siRNA) cargo into Ewing sarcoma cells. The siRNA is delivered after adsorption onto NDs that have been coated with a cationic polymer. The use of NDs as siRNA delivery vehicles points to the possibility of in-vivo anticancer nucleic-acid drug delivery.