Dendritische Nanostrukturen zur rezeptorvermittelten Aufnahme von siRNA in neurale Zellen

Enhanced Immunostimulatory Activity of Covalent DNA Dendrons

The present study focused on the design and synthesis of covalent DNA dendrons bearing multivalent cytosine-phosphate-guanine oligodeoxynucleotides (CpG ODNs) that can stimulate the immune system through the activation of TLR9. These dendrons were synthesized using branching trebler phosphoramidite containing three identical protecting groups that enabled the simultaneous synthesis of multiple strands on a single molecule. Compared with linear ODNs, covalent DNA dendrons were found to be more resistant to nuclease degradation and were more efficiently taken up by macrophage-like RAW264.7 cells. Cellular uptake was suggested to be mediated by macrophage scavenger receptors. The covalent DNA dendrons composed of multivalent immunostimulatory branches enhanced the secretion of proinflammatory cytokines TNF-α and IL-6 from RAW264.7 cells, and 9-branched DNA dendrons showed the highest enhancement. Given their enhanced efficacy, we expect covalent DNA dendrons to be useful structures of oligonucleotide medicines.

Transition-Metal-Mediated Modification of Biomolecules

The site-selective modification of biomolecules has grown spectacularly in recent years. The presence of a large number of functional groups in a biomolecule makes its chemo- and regioselective modification a challenging goal. In this context, transition-metal-mediated reactions are emerging as a powerful tool owing to their unique reactivity and good functional group compatibility, allowing highly efficient and selective bioconjugation reactions that operate under mild conditions. This Minireview focuses on the current state of organometallic chemistry for bioconjugation, highlighting the potential of transition metals for the development of chemoselective and site-specific methods for functionalization of peptides, proteins and nucleic acids. The importance of the selection of ligands attached to the transition metal for conferring the desired chemoselectivity will be highlighted.

Branch-PCR Constructed Stable shRNA Transcription Nanoparticles Have Long-Lasting RNAi Effect

RNA interference (RNAi) is a cellular process for gene silencing. Because of poor serum stability, transferring dsRNA directly into the target cells is a challenge. We report a facile and universal strategy to construct short hairpin RNA (shRNA) transcription nanoparticles with multiple shRNA transcription templates by PCR with flexible branched primers (branch-PCR). Compared with conventional linear shRNA transcription templates, these shRNA transcription nanoparticles show excellent stability against digestion by exonuclease III. Importantly, we found that our highly stable shRNA transcription nanoparticles can also be transcribed and thus induce efficient and long-lasting RNAi with picomolar activity in living mammalian cells. These chemically well-defined branch-PCR-generated stable shRNA transcription nanoparticles might facilitate RNAi delivery with a long-lasting RNAi effects.