Viral Mimicry as a Design Template for Nucleic Acid Nanocarriers.

Therapeutic nucleic acids hold immense potential in combating undruggable, gene-based diseases owing to their high programmability and relative ease of synthesis. While the delivery of this class of therapeutics has successfully entered the clinical setting, extrahepatic targeting, endosomal escape efficiency, and subcellular localization. On the other hand, viruses serve as natural carriers of nucleic acids and have acquired a plethora of structures and mechanisms that confer remarkable transfection efficiency. Thus, understanding the structure and mechanism of viruses can guide the design of synthetic nucleic acid vectors. This review revisits relevant structural and mechanistic features of viruses as design considerations for efficient nucleic acid delivery systems. This article explores how viral ligand display and a metastable structure are central to the molecular mechanisms of attachment, entry, and viral genome release. For comparison, accounted for are details on the design and intracellular fate of existing nucleic acid carriers and nanostructures that share similar and essential features to viruses. The review, thus, highlights unifying themes of viruses and nucleic acid delivery systems such as genome protection, target specificity, and controlled release. Sophisticated viral mechanisms that are yet to be exploited in oligonucleotide delivery are also identified as they could further the development of next-generation nonviral nucleic acid vectors.

Controlled release of small molecules and proteins from DNA-surfactant stabilized metal organic frameworks.

This work highlights a multifunctional nanoscale material which can effectively compartmentalize small molecules and biomolecules into a single, micellar structure with programmable degradation properties resulting in highly controllable release properties. The nanomaterial consists of a ZIF-8 metal organic framework (MOF) encapsulated within a DNA surfactant micelle assembly, referred to as a nucleic acid nanocapsule (NAN). NANs have been demonstrated to enter cells through endocytosis and result in intracellular cargo release upon enzyme-triggered degradation. By combining the favorable properties of MOFs (large storage capacity) with those of NANs (triggerable release), we show diverse molecular cargo can be integrated into a single, highly programmable nanomaterial with controllable release profiles. The hybrid MOF-NANs exhibit double-gated regulation capabilities as evidenced by kinetic studies of encapsulated enzymes that indicate individual layers of the particle influence the overall enzymatic rate of turnover. The degradation of MOF-NANs can be controlled under multiple combined stimuli (i.e. varying pH, enzymes), enabling selective release profiles in solutions representative of more complex biological systems. Lastly, the enhanced control over the release of small molecules, proteins and plasmids, is evaluated through a combination of cell culture and in vitro fluorescence assays, indicating the potential of MOF-NANs for both therapeutic and diagnostic applications.

Enzymatically Ligated DNA-Surfactants: Unmasking Hydrophobically Modified DNA for Intracellular Gene Regulation.

Herein, we describe the characterization of a novel self-assembling and intracellular disassembling nanomaterial for nucleic acid delivery and targeted gene knockdown. By using a recently developed nucleic acid nanocapsule (NAN) formed from surfactants and conjugated DNAzyme (DNz) ligands, it is shown that DNz-NAN can enable cellular uptake of the DNAzyme and result in 60 % knockdown of a target gene without the use of transfection agents. The DNAzyme also exhibits activity without chemical modification, which we attribute to the underlying nanocapsule design and release of hydrophobically modified nucleic acids as a result of enzymatically triggered disassembly of the NAN. Fluorescence-based experiments indicate that the surfactant-conjugated DNAzymes are better able to access a fluorescent mRNA target within a mock lipid bilayer system than the free DNAzyme, highlighting the advantage of the hydrophobic surfactant modification to the nucleic acid ligands. In vitro characterization of DNz-NAN's substrate-cleavage kinetics, stability in biological serum, and persistence of knockdown against a proinflammatory transcription factor, GATA-3, are presented.