Hollow Inorganic Nanoparticles as Efficient Carriers for siRNA Delivery: A Comprehensive Review

Small interfering RNAs (siRNA) are emerging as a new opportunity for treatment of various diseases, including viral and cancer diseases via knocking down a specific gene that involves in disease development. But their clinical application is hampered because of susceptibility to degradation and difficult delivery of siRNA into cells. So it is needed to develop an efficient carrier that stabilizes and delivers siRNA efficiently and specifically into cells. Hollow inorganic nanoparticles have gained considerable attention as an efficient drug and gene delivery system. This is due to their biocompatibility, simple preparative processes, easy functionalization and high capacity for drug loading. Several nanoparticle platforms for siRNA delivery have been developed to overcome the major limitations facing the therapeutic uses of siRNA. Recently, researchers have developed a wide range of inorganic nanocarriers to increase efficacy of si-RNA-based drugs and gained efficient siRNA delivery both in vitro and in vivo. This review covers a broad spectrum of hollow inorganic nanoparticles as non-viral siRNA delivery systems. These nanoparticles are developed for enhanced cellular uptake and targeted gene silencing in vitro and in vivo and their characteristics and opportunities for clinical applications of therapeutic siRNA are discussed in this article. Various types of inorganic hollow nanovectors including: mesoporous silica nanoparticles, carbon nanotubes, graphene oxide, fullerenes, calcium phosphate nanoparticles, hollow manganese oxide, gold nanoshells, and layered double hydroxide nanoparticles used to deliver siRNA are introduced and the development of theranostics and combinational treatment is also discussed.