A DNA-Based Plasmonic Nano-Ruler.

Area of Science:

• Supramolecular Chemistry
• Nanotechnology
• Biophysics

Background:

• DNA's unique properties enable the creation of dynamic supramolecular systems with adaptable geometries.
• Self-assembled nanostructures are crucial for developing advanced molecular devices.
• Plasmonic and fluorescent interactions are key to nanoscale sensing and imaging.

Purpose of the Study:

• To engineer a tunable plasmonic-fluorescent nanostructure using DNA.
• To create a DNA-based nano-ruler with switchable configurations and distinct signal outputs.
• To explore the application of this nanostructure in detecting single-strand nucleic acids.

Main Methods:

• Fabrication of a self-assembled nanostructure using single-strand DNA (ssDNA) rails and a quasi-ring structure.
• Utilizing strand displacement reactions to control a precise sliding motion mechanism.
• Integrating gold nanoparticles (AuNPs) and a fluorophore (Sulfo-Cyanine3) to investigate plasmonic effects.
• Analyzing distance-dependent fluorescence quenching and enhancement phenomena with varying AuNP sizes.

Main Results:

• A DNA-based nano-mechanical structure was successfully developed, exhibiting six discrete configurations.
• The nanostructure demonstrated tunable fluorescence emission intensities based on controlled distances between AuNPs and the fluorophore.
• Optimal performance was achieved using 10 nm AuNPs, confirming the distance-dependent plasmonic effects.
• A geometric model validated the experimental observations of the nanostructure's behavior.

Conclusions:

• The DNA nanostructure functions as a finite-state nano-machine with six distinct signal outputs, acting as a fluorescent reporter.
• The precise control over fluorophore-plasmonic surface positioning enables applications in multiple-responsive detection systems.
• This technology holds promise for the sensitive detection of single-strand nucleic acids, including viruses and microRNAs.