Unraveling DNA Using Gold Nanoparticles

Scientists from North Carolina State University (NC State; Raleigh) have discovered that gold nanoparticles with a slightly positive charge work collectively to unravel DNA's double helix. This finding has ramifications for gene therapy research and the emerging field of DNA-based electronics.

The research team introduced approximately 1.5-nm-diam gold nanoparticles into a solution containing double-stranded DNA. The nanoparticles were coated with organic molecules called ligands, some holding a positive charge and others being hydrophobic. Because some of the gold nanoparticles had a slight positive charge and DNA is always negatively charged, the DNA and nanoparticles were pulled together.

In addition to the powers of attraction exhibited by the DNA and the gold nanoparticles, the scientists found that the nanoparticles unzipped the DNA, remarks Anatoli Melechko, an associate professor of materials science and engineering at NC State and coauthor of a paper describing this research in Advanced Materials. The positively charged ligands on the nanoparticles attached to the DNA as predicted, but the hydrophobic ligands of the nanoparticles became tangled with each other, pulling the nanoparticles into clusters. At the same time, the nanoparticles pulled the DNA apart, as shown in the video below.

"We think gold nanoparticles still hold promise for gene therapy," says Yaroslava Yingling, an assistant professor of materials science and engineering at NC State and coauthor of the paper. "But it's clear that we need to tailor the ligands, charge, and chemistry of these materials to ensure the DNA's structural integrity is not compromised."