Bright G-Quadruplex Nanostructures Functionalized with Porphyrin Lanterns.

Area of Science:

• Supramolecular chemistry
• Nanotechnology
• Photonic materials

Background:

• Dense chromophore arrangement on nanoscale scaffolds enables photonic applications.
• DNA self-assembly of dye-appended sequences offers programmed photonic architectures.
• Challenges include compromised DNA assembly and nonfluorescent systems due to dye aggregation.

Purpose of the Study:

• To develop a strategy for creating bright, densely packed dye nanomaterials using aqueous self-assembly.
• To overcome limitations of dye aggregation in DNA-based photonic structures.
• To enable the bottom-up fabrication of novel fluorescent nanomaterials.

Main Methods:

• A two-step "tether and mask" strategy was employed.
• Large porphyrin dyes were attached to G-quadruplex-forming DNA sequences.
• Per-O-methylated β-cyclodextrin (PMβCD) caps were used to mask porphyrin dyes, forming supramolecular synthons.
• These masked porphyrin-DNA (PL-DNA) sequences were self-assembled into cyclic architectures and G-wires.

Main Results:

• The "tether and mask" strategy successfully created masked porphyrin lantern (PL) states.
• PL-DNA sequences self-assembled into cyclic architectures and G-wires with hundreds of porphyrin dyes.
• Despite dense packing (∼2 nm), the masked porphyrin dyes exhibited significantly enhanced brightness (up to 180-fold).
• The PMβCD masks prevented π-π aggregation, preserving dye fluorescence.

Conclusions:

• The "tether and mask" strategy is effective for creating bright, densely packed dye nanomaterials in aqueous solution.
• This modular approach overcomes dye aggregation issues in self-assembled systems.
• The method provides a general strategy for bottom-up fabrication of advanced fluorescent nanomaterials for photonic applications.