Encapsulating Active Pharmaceutical Ingredients in Self-Assembling Adamantanes with Short DNA Zippers

Hybridization Networks of mRNA and Branched RNA Hybrids

Messenger RNA (mRNA) is emerging as an attractive biopolymer for therapy and vaccination. To become suitable for vaccination, mRNA is usually converted to a biomaterial, using cationic peptides, polymers or lipids. An alternative form of converting mRNA into a material is demonstrated that uses branched oligoribonucleotide hybrids with the ability to hybridize with one or more regions of the mRNA sequence. Two such hybrids with hexamer arms and adamantane tetraol as branching element were prepared by solution-phase synthesis. When a rabies mRNA was treated with the branched hybrids at 1 M NaCl concentration, biomaterials formed that contained both of the nucleic acids. These results show that branched oligoribonucleotides are an alternative to the often toxic reagents commonly used to formulate mRNA for medical applications.

Turning DNA Binding Motifs into a Material for Flow Cells

Nanoscale assemblies of DNA strands are readily designed and can be generated in a wide range of shapes and sizes. Turning them into solids that bind biomolecules reversibly, so that they can act as active material in flow cells, is a challenge. Among the biomolecular ligands, cofactors are of particular interest because they are often the most expensive reagents of biochemical transformations, for which controlled release and recycling are desirable. We have recently described DNA triplex motifs that bind adenine-containing cofactors, such as NAD, FAD and ATP, reversibly with low micromolar affinity. We sought ways to convert the soluble DNA motifs into a macroporous solid for cofactor binding. While assemblies of linear and branched DNA motifs produced hydrogels with undesirable properties, long DNA triplexes treated with protamine gave materials suitable for flow cells. Using exchangeable cells in a flow system, thermally controlled loading and discharge were demonstrated. Employing a flow cell loaded with ATP, bioluminescence was induced through thermal release of the cofactor. The results show that materials generated from functional DNA structures can be successfully employed in macroscopic devices.

Stabilizing DNA nanostructures through reversible disulfide crosslinking

Designed DNA nanostructures can be generated in a wide range of sizes and shapes and have the potential to become exciting tools in material sciences, catalysis and medicine. However, DNA nanostructures are thermally labile assemblies of delicate biomacromolecules, and the lability hampers the use in many applications. Disulfide crosslinking is nature's successful approach to stabilize folded proteins against denaturation. It is therefore interesting to ask whether similar approaches can be used to stabilize DNA nanostructures. Here we report the synthesis of two 2'-deoxynucleoside phosphoramidites and two nucleosides linked to controlled pore glass that can be used to prepare oligodeoxynucleotides with protected thiol groups via automated DNA synthesis. Strands with one, two, three or four thiol-bearing nucleotides were prepared. One nicked duplex and three different nanostructures were assembled, the protected thiols were liberated under non-denaturing conditions, and disulfide crosslinking was induced with oxygen. Up to 19 crosslinks were thus placed in folded DNA structures up to 1456 nucleotides in size. The crosslinked structures had increased thermal stability, with UV-melting points 9-50 °C above that of the control structure. Disulfides were converted back to free thiols under reducing conditions. The redox-dependent increase in stability makes crosslinked DNA nanostructures attractive for the construction of responsive materials and biomedical applications.

Theobromine cocrystals with monohydroxybenzoic acids – synthesis, X-ray structural analysis, solubility and thermal properties

Theobromine, a compound from the purine alkaloid group, is much less soluble in polar solvents than its analogues, i.e. caffeine and theophylline, that is why it was used as an active pharmaceutical ingredient (API) model in cocrystal preparation.

Encapsulating Active Pharmaceutical Ingredients in Self-Assembling Adamantanes with Short DNA Zippers

Formulating pharmaceutically active ingredients for drug delivery is a challenge. There is a need for new drug delivery systems that take up therapeutic molecules and release them into biological systems. We propose a novel mode of encapsulation that involves matrices formed through co-assembly of drugs with adamantane hybrids that feature four CG dimers as sticky ends. Such adamantanes are accessible via inexpensive solution-phase syntheses, and the resulting materials show attractive properties for controlled release. This is demonstrated for two different hybrids and a series of drugs, including anticancer drugs, antibiotics, and cyclosporin. Up to 20 molar equivalents of active pharmaceutical ingredients (APIs) are encapsulated in hybrid materials. Encapsulation is demonstrated for DNA-binding and several non-DNA binding compounds. Nanoparticles were detected that range in size from 114-835 nm average diameter, and ζ potentials were found to be between -29 and +28 mV. Release of doxorubicin into serum at near-constant rates for 10 days was shown, demonstrating the potential for slow release. The encapsulation and release in self-assembling matrices of dinucleotide-bearing adamantanes appears to be broadly applicable and may thus lead to new drug delivery systems for APIs.