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Gold nanoparticles capable of 'unzipping' DNA

Date:
June 20, 2012
Source:
North Carolina State University
Summary:
Gold nanoparticles with a slight 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.

As the nanoparticles cluster together, they pull the strands of DNA apart.
Credit: Image courtesy of North Carolina State University

New research from North Carolina State University finds that gold nanoparticles with a slight 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.

"We began this work with the goal of improving methods of packaging genetic material for use in gene therapy," says Dr. Anatoli Melechko, an associate professor of materials science and engineering at NC State and co-author of a paper describing the research. Gene therapy is an approach for addressing certain medical conditions by modifying the DNA in relevant cells.

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. Some of the ligands held a positive charge, while others were hydrophobic -- meaning they were 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," Melechko says. 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.

"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.

Video: http://www.youtube.com/watch?v=9M-58niEOpU&feature=colike


Story Source:

The above story is based on materials provided by North Carolina State University. Note: Materials may be edited for content and length.


Journal Reference:

  1. Justin G. Railsback, Abhishek Singh, Ryan C. Pearce, Timothy E. McKnight, Ramσn Collazo, Zlatko Sitar, Yaroslava G. Yingling, Anatoli V. Melechko. Weakly Charged Cationic Nanoparticles Induce DNA Bending and Strand Separation. Advanced Materials, 2012; DOI: 10.1002/adma.201104891

Cite This Page:

North Carolina State University. "Gold nanoparticles capable of 'unzipping' DNA." ScienceDaily. ScienceDaily, 20 June 2012. <www.sciencedaily.com/releases/2012/06/120620113242.htm>.
North Carolina State University. (2012, June 20). Gold nanoparticles capable of 'unzipping' DNA. ScienceDaily. Retrieved October 20, 2014 from www.sciencedaily.com/releases/2012/06/120620113242.htm
North Carolina State University. "Gold nanoparticles capable of 'unzipping' DNA." ScienceDaily. www.sciencedaily.com/releases/2012/06/120620113242.htm (accessed October 20, 2014).

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