February 28, 2005

Purdue researchers use enzyme to clip 'DNA wires'

WEST LAFAYETTE, Ind. – Researchers at Purdue University have attached magnetic "nanoparticles" to DNA and then cut these "DNA wires" into pieces, offering the promise of creating low-cost, self-assembling devices for future computers.

DNA wires
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Findings are detailed in a paper published online in February in the Journal of the American Chemical Society. The paper was written by Purdue graduate student Joseph M. Kinsella and Albena Ivanisevic, an assistant professor of biomedical engineering and chemistry at Purdue.

DNA, or deoxyribonucleic acid, has an overall negative charge, so it might be used in a process called self-assembly to create electronic devices. When placed in a solution with magnetic particles that have a positive charge, the particles are automatically attracted to the DNA strands, which act as tiny scaffolds for creating wires.

Other researchers have "metalized" DNA by coating it with copper, gold and platinum, but no other researchers have coated DNA and then cut the strands into smaller pieces using a "restriction enzyme," a class of enzyme that causes DNA to fragment, Kinsella said.

Because magnetic components are essential for today's computer memory, the findings represent potential future applications for DNA-based structures in computers created with "molecular electronics," in which biological molecules might be harnesses to create devices for computers, sensors and other uses. Self-assembly might be used in the future to create electronic devices at lower cost than is possible with conventional manufacturing processes.

Purdue researchers had previously developed a technique for precisely placing strands of DNA on a silicon chip and then stretching out the strands so that their encoded information might be read more clearly. The current work by Ivanisevic's team builds on that previous research.

Kinsella created the magnetic particles, which are made from a ceramic iron oxide material about 4 nanometers in diameter. A nanometer is one billionth of a meter, or roughly 10 times the size of a hydrogen atom.

The Purdue researchers sliced the DNA wires with an enzyme called BamH1, one of numerous restriction enzymes that are used in standard genetic engineering techniques to snip DNA so that scientists can alter the genetic structures of organisms like bacteria.

DNA molecules contain "bases" called guanine, adenine, thymine and cytosine, represented as G, A, T and C. The bases combine in numerous sequences, and various restriction enzymes atta