Researchers find gold nanoparticles capable of ‘unzipping’ DNA
June 21, 2012
New research from North Carolina State University finds that gold nanoparticles with a slight positive charge work collectively to unravel DNA’s double helix — a finding with ramifications for gene therapy research and the emerging field of DNA-based electronics.
The research team introduced gold nanoparticles, approximately 1.5 nanometers in diameter, into a solution containing double-stranded DNA. The nanoparticles were coated with organic molecules called ligands (an ion or molecule that binds to a central metal atom).
Some of the ligands held a positive charge, while others were hydrophobic (repelled by water).
Because the gold nanoparticles had a slight positive charge from the ligands, and DNA is always negatively charged, the DNA and nanoparticles were pulled together into complex packages.
“However, we found that the DNA was actually being unzipped by the gold nanoparticles,” says Dr. Anatoli Melechko, an associate professor of materials science and engineering at NC State. 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. As this tangling pulled the nanoparticles into clusters, the nanoparticles pulled the DNA apart. Video of how the process works is available here.
“We think gold nanoparticles still hold promise for gene therapy,” says Dr. Yaroslava Yingling, an assistant professor of materials science and engineering at NC State and co-author 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.”
The finding is also relevant to research on DNA-based electronics, which hopes to use DNA as a template for creating nanoelectronic circuits. Because some work in that field involves placing metal nanoparticles on DNA, this finding indicates that researchers will have to pay close attention to the characteristics of those nanoparticles — or risk undermining the structural integrity of the DNA.
The research was supported by the National Science Foundation.