Researchers Develop Nanoscale Probes for ssDNA Sustainability under UV radiation

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It was only when they assumed that the DNA was the source of the observed phenomenon--and rejected a widely accepted model--that the researchers were they able to fully understand nanotube optical quenching.

DNA is very useful for studying nanotubes. A strand of DNA wrapped around a single carbon nanotube-- a miniature cylindrical carbon structure that has a hexagonal graphite lattice and walls that are only one atom thick--will hold the nanotube in water and allow it to have practically the same good optical properties as pristine material.

Initially, the researchers were surprised to observe changes in the nanotube's optical properties as the UV light was applied to the samples.

"For years it has been commonly accepted that DNA is an 'inert' carrier for nanotubes and that DNA holds the nanotube in water without changing its properties," added Rotkin. "It took several years for our team to part with this commonly-held idea, because it was so broadly accepted. Finally, after a series of additional experiments, the data clearly indicated the origin of the modulation to be the DNA itself."

On the heels of this discovery, the researchers have shifted the focus of their project to see how their two-color photoluminescence spectroscopy technique could be used to further probe the properties of DNA.

"It is now understood that different DNA nucleobases show different autoionization properties," concluded Rotkin. "We anticipate this will create unprecedented non-invasive biomolecular tools for solving critical problems of biophysics of nucleic acids."

The study was funded by the National Science Foundation (NSF:ECCS) within the project called "Fundamental physics and biosensing applications of composite fluorescent nanomaterials - rare-earths combined with DNA-enclosed carbon nanotubes."

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