Core-shell hybrid nanostructured delivery platforms for advanced RNAi therapeutics

Hybrid Nanosystems for Biomedical Applications

Inorganic/organic hybrid nanosystems have been increasingly developed for their versatility and efficacy at overcoming obstacles not readily surmounted by nonhybridized counterparts. Currently, hybrid nanosystems are implemented for gene therapy, drug delivery, and phototherapy in addition to tissue regeneration, vaccines, antibacterials, biomolecule detection, imaging probes, and theranostics. Though diverse, these nanosystems can be classified according to foundational inorganic/organic components, accessory moieties, and architecture of hybridization. Within this Review, we begin by providing a historical context for the development of biomedical hybrid nanosystems before describing the properties, synthesis, and characterization of their component building blocks. Afterward, we introduce the architectures of hybridization and highlight recent biomedical nanosystem developments by area of application, emphasizing hybrids of distinctive utility and innovation. Finally, we draw attention to ongoing clinical trials before recapping our discussion of hybrid nanosystems and providing a perspective on the future of the field.

Tripodal RNA with 3' Overhangs Prevents RIG-I-Mediated Innate Immune Response

RNA interference (RNAi) offers great promise in life science research and therapeutic development, as it easily achieves a potent target gene knockdown with high specificity. Since the conventional small interfering RNA (siRNA) structure, known as 19 bp double-stranded RNA (dsRNA) with 2-nucleotide (nt) 3' overhang, has been introduced to successfully elicit the RNAi in mammalian cells, a variety of structural variants of RNAi trigger have been developed. Our group previously reported branched, tripodal interfering RNA (tiRNA) structures as a multigene targeting RNA structure inducing RNAi. However, the immune stimulatory effect of branched tiRNA structure has not been thoroughly evaluated. In this study, we show that tiRNA with blunt ends triggers innate immune response in T98G cell and mouse macrophage cells, which is dependent upon the retinoic acid-inducible gene I (RIG-I), a well-known cytoplasmic dsRNA sensor. Interestingly, immune response triggered by tiRNA can be suppressed by the introduction of 2-nt 3' overhang structure. Our finding expands the structural diversity of RIG-I ligands and provides a guide to develop a safe multitargeting RNA structure for therapeutic application.

Current status and future perspectives of gold nanoparticle vectors for siRNA delivery

Discovering the vast therapeutic potential of siRNA opened up new clinical research areas focussing on a number of diseases and applications; however significant problems with siRNA stability and delivery have hindered its clinical applicability. As a result, interest in the development of practical siRNA delivery systems has grown in recent years. Of the numerous siRNA delivery strategies currently on offer, gold nanoparticles (AuNPs) stand out thanks to their biocompatibility and capacity to protect siRNA against degradation; not to mention the versatility offered by their tuneable shape, size and optical properties. Herein this review provides a complete summary of the methodologies for functionalizing AuNPs with siRNA, paying singular attention to the AuNP shape, size and surface coating, since these key factors heavily influence cellular interaction, internalization and, ultimately, the efficacy of the hybrid particle. The most noteworthy hybridization strategies have been highlighted along with the most innovative and outstanding in vivo studies with a view to increasing clinical interest in the use of AuNPs as siRNA nanocarriers.