Minimalist Design of a Stimuli-Responsive Spherical Nucleic Acid for Conditional Delivery of Oligonucleotide Therapeutics

Abstract

In this work, we report a component-minimal spherical nucleic acid (SNA) from monodisperse DNA− polymer conjugates that can load and release nucleic acid therapeutics in a stimuli-responsive manner. We show that this vehicle assembles from only four strands, and conditional release of its antisense therapeutic cargo can be induced upon recognition of specific oligonucleotide triggers via strand displacement. The latter (triggers) may be a microRNA that offers additional synergistic therapy, in addition to the previously shown ability of the SNA to load hydrophobic drugs. The SNA is easy to prepare, has dynamic character, releases its cargo only upon the presence of both triggers, and can survive biological conditions while protecting its cargo. The gene silencing potency of the cargo was tested in live cells and shown to be suppressed when loaded in the SNA, and its activity was restored only upon release with the two triggers. This vehicle has the essential characteristics of versatility, ease of synthesis, low cost, highly responsive behavior, and ability to support combination therapies, making it a promising candidate for cell-selective drug delivery and clinical transition.

Design and enhanced gene silencing activity of spherical 2′-fluoroarabinose nucleic acids (FANA-SNAs)

“…2 , the ASO-conjugates form well-defined spherical structures with a comparable size to previously characterized SNAs. 48,49 The addition of spacer led to a slight increase in size for the FANA-(PO-dN 4 )-SNA. In both cases, the larger features observed by AFM are attributed to dimers or small aggregates resulting from the AFM conditions (dried sample on mica surface) and the palindromic nature of part of the sequence.…”

“…This allows it to assemble into an exceptionally stable monodisperse particle of tuneable properties (size, shape, functionality, biodistribution) for delivery. 48,49,55 FANA has the benefit of increasing gene silencing efficacy, nuclease resistance and reduced immune-stimulatory side-effects. 4–9,11 …”

“… 34–36 They also show higher activity (2–3-fold), requiring less transfection agents compared to linear nucleic acids, 33 and they can be designed to release cargo in the presence of specific biomolecules. 36 Furthermore, these SNAs are assembled from a single component in comparison to other nucleic acid based structures such as origami, 37 making them DNA-minimal and favourable in terms of large-scale production and translation into clinical applications. 18,38 In comparison to other SNAs, our sequence-controlled polymeric SNAs are made from biocompatible, biodegradable materials, can encapsulate small molecule drugs and allow for near infinite variation in polymer chemistry and sequence in an automated fashion.…”

Hydrophobic Interaction: A Promising Driving Force for the Biomedical Applications of Nucleic Acids

“…[133,134] To solve this limitation, Sleiman's group proposed an idea to design a stimuli-responsive SNA that could precisely inhibit a specific gene in target cells. [135] The SNA was assembled by two "pillar" like DNA-polymer conjugates, partially hybridized by a "bridge" like DNA, on which the ASO "cargo" against luciferase could be further hybridized. The responsive process could be initiated by the overexpressed miRNA in target cells, which subsequently triggered the release of the ASO for mRNA regula-tion.…”

Functional Nucleic‐Acid‐Decorated Spherical Nanoparticles: Preparation Strategies and Current Applications in Cancer Therapy

“…In addition, a two triggers-responsive ASO-modified micellar nanostructure was designed by Fakih et al (Figure 4c). [161] The micelles were prepared using three components: two "pillar" DNA-polymer amphiphilic strands and a "bridge" strand. The two "pillar" strands were designed for responding to two specific cytoplasmic genetic markers (e.g., miRNAs) that are overexpressed in cancer cells.…”