The molecule of life just got a new job description. University of Florida scientists have coaxed a piece of DNA to act in concert with a filter-like membrane and tiny hollow tubes called nanotubes to find and retrieve other DNA dissolved in a solution. It’s the first time researchers have turned to a nanotube filter based on DNA to perform a task now routine in medical research, criminal forensics and other areas.
From University of Florida :
DNA IN NANOTUBES SERVES AS GENE CAPTURER FOR MEDICINE, FORENSICS, ETC.
The molecule of life just got a new job description.
University of Florida scientists have coaxed a piece of DNA to act in concert with a filter-like membrane and tiny hollow tubes called nanotubes to find and retrieve other DNA dissolved in a solution. It’s the first time researchers have turned to a nanotube filter based on DNA to perform a task now routine in medical research, criminal forensics and other areas.
An article about the research, authored by several scientists in UF chemistry professor Charles Martin’s laboratory, is scheduled to appear Friday in the journal Science.
”The central feature of this work is the separation of DNA chains, a critical component, for example, of the Human Genome Project,” Martin said, referring to the massive endeavor that produced the first map of the human genetic code in 2000. ”We’re looking to the future here, to what other technologies might work and where they might be needed.”
Although applications are years away, the technique has the potential to speed or improve both the gene-sensing and gene-separation technologies that are rapidly becoming central to health care, bioterrorism detection and other areas.
”This work can provide an important improvement in genomic sequencing procedures,” said Michael Sailor, a professor in the department of chemistry and biochemistry at the University of California, San Diego. ”This is useful for making more accurate disease diagnosis. In the area of homeland defense, this method will aid in the detection of pathogens in food, water and air.”
The feat also is noteworthy as the latest example of scientists turning to DNA for ends well apart from its biological function of passing on the hereditary blueprint of life. In 2003, for example, Israeli scientists announced they had built a primitive DNA ”nanocomputer” – one nanometer equals one-billionth of a meter – consisting of DNA and DNA-processing enzymes.
And in 2000, University of Oxford and Bell Labs researchers built a DNA motor, resembling a pair of automated tweezers, they said could one day be used as a kind of molecular machine to manufacture such things as computer memory devices.
”What’s cool about DNA is that you can zip or unzip the double helix, and this can be done at will,” Martin said, referring to the complementary and intertwined DNA chains that make up the helical structure responsible for the storage of genetic information. ”That makes it very attractive for doing things like self-assembling nanoparticles and for a number of other applications in nanotechnology.”
Martin, director of UF’s Center for Research at the Bio/Nano Interface, said one objective of his research is to find more efficient methods for chemical separations, the processes used for tasks ranging from obtaining useful petroleum products from crude oil to purifying the drugs used to treat diseases. Typically, he said, the largest single cost of bringing a chemical or pharmaceutical product to market is chemical separations.
He announced in Science two years ago that he had created nanotube membranes containing antibodies that could be used to purify cancer-fighting drugs. The latest research continues this theme of ”smart” nanotubes.
Martin arrayed tailored strands of DNA molecules inside nanotubes within a membrane. Those nanotube-bound strands captured complementary DNA molecules in a solution on one side of the membrane and shuttled them through the nanotubes to a receiver solution on the membrane’s other side. A remarkable aspect of his experiments’ results is their specificity: When given a choice between a DNA strand perfectly complementary to the DNA in the nanotubes or one that contained only one mismatched base, the nanotube membrane shuttled the perfectly complementary DNA five times faster than the DNA with the single mismatch. ”That’s the ultimate test of selectivity: Can it recognize a single base mismatch?” Martin said.
One possible snag for the nanotube membranes is the amount of DNA transported, or the ”flux” of DNA across the membrane.
”Higher fluxes would be useful for some applications,” such as separating bulk materials Martin said. ”But the fluxes seen in the experiments are certainly high enough for gene-sensing applications, and the membrane approach might yield higher sensitivities than currently available gene-chip technology.”
Chip-based ”biosensing” technology finds specific genes that cause disease or identify bioterrorism agents. ”There’s nothing wrong with that technology, but it is always desirable to have greater sensitivity and greater selectivity,” Martin said.
