A modular RNA delivery system comprising spherical nucleic acids built on endosome-escaping polymeric nanoparticles

Nucleic acid therapeutics require delivery systems to reach their targets. Key challenges to be overcome include avoidance of accumulation in cells of the mononuclear phagocyte system and escape from the endosomal pathway. Spherical nucleic acids (SNAs), in which a gold nanoparticle supports a corona of oligonucleotides, are promising carriers for nucleic acids with valuable properties including nuclease resistance, sequence-specific loading and control of receptor-mediated endocytosis. However, SNAs accumulate in the endosomal pathway and are thus vulnerable to lysosomal degradation or recycling exocytosis. Here, an alternative SNA core based on diblock copolymer PMPC25–PDPA72 is investigated. This pH-sensitive polymer self-assembles into vesicles with an intrinsic ability to escape endosomes via osmotic shock triggered by acidification-induced disassembly. DNA oligos conjugated to PMPC25–PDPA72 molecules form vesicles, or polymersomes, with DNA coronae on luminal and external surfaces. Nucleic acid cargoes or nucleic acid-tagged targeting moieties can be attached by hybridization to the coronal DNA. These polymeric SNAs are used to deliver siRNA duplexes against C9orf72, a genetic target with therapeutic potential for amyotrophic lateral sclerosis, to motor neuron-like cells. By attaching a neuron-specific targeting peptide to the PSNA corona, effective knock-down is achieved at doses of 2 particles per cell

Inhibition of Multimolecular RNA–Protein Interactions Using Multitarget-Directed Nanohybrid System

Multitarget-directed ligands (MTDLs) are hybrid ligands obtained by covalently linking active pharmacophores that can act on different targets. We envision that the concept of MTDLs can also be applied to supramolecular bioinorganic nanohybrid systems. Here, we report the inhibition of multimolecular RNA–protein complexes using multitarget-directed peptide–carbon nanotube hybrids (SPCHs). One of the most well-characterized and important RNA–protein interactions, a Rev-response element (RRE) RNA:Rev protein:Crm1 protein interaction system in human immunodeficiency virus type-1, was used as a model of multimolecular RNA–protein interactions. Although all previous studies have targeted only one of the interaction interfaces, that is, either the RRE:Rev interface or the RRE–Rev complex:Crm1 interface, we here have developed multitarget-directed SPCHs that could target both interfaces because the supramolecular nanosystem could be best suited for inhibiting multimolecular RNA–protein complexes that are characterized by large and complex molecular interfaces. The results showed that the single target-directed SPCHs were inhibitory to the single interface comprised only of RNA and protein in vitro, whereas multitarget-directed SPCHs were inhibitory to the multimolecular RNA–protein interfaces both in vitro and in cellulo. The MTDL nanohybrids represent a novel nanotherapeutic system that could be used to treat complex disease targets