Synthesis of Gold Nanoparticles for Gene Silencing

Over the last decade, the capability of double-stranded RNAs to interfere with gene expression has driven new therapeutic approaches. Since small interfering RNAs (siRNAs, 21-base-pair double-stranded RNA) were shown able to elicit RNA interference (RNAi), efforts were directed toward the development of efficient delivery systems to preserve siRNA bioactivity throughout the delivery route, from administration site to the target cell. Starting from the synthesis of gold nanoparticle, here we describe comprehensive methodologies for functionalization with specific moieties (charged groups, peptides) and chemico-physical characterization. Moreover, we report two different strategies that can be used to bind siRNA molecules on the gold nanoparticle: a covalent approach, based on thiolated siRNA bound via a thiol bond to nanoparticle surface, and an ionic approach based on the electrostatic interaction between the negatively charged siRNA backbone and azide and quaternary ammonium groups positively charged anchored on the nanoparticle surface. Both methodologies were shown highly efficient for siRNA delivery, achieving specific gene silencing in in vitro and in vivo biological systems.