Microcantilevers Speed DNA Sequencing
sensorsmag.com
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We first brought Thomas Thundat’s research into microcantilevers to your attention in January 1997, and we are happy to convey a report from the Oak Ridge National Laboratory Review that his work has continued. He and colleague Karolyn Hansen, both of the lab’s Life Sciences Division, are currently investigating the cantilevers (about the size of the dot over this “i”) as a method of distinguishing between numbers of base pairs in DNA sequences.
They begin by attaching thiolated single-stranded DNA containing 20 bases to a series of gold-coated cantilevers. Next they allow 20, 15, 10, and 9 bases of single-stranded DNA of different sequences to come into contact with the attached samples. It turns out that changes in surface tension as a result of DNA hybridization cause all the cantilevers to bend. This bending, which increases with the number of bases a cantilever holds, is detected by the deflection of a laser light and the data are stored. The technique is faster than conventional analytical methods because it does not require the addition of fluorescent dyes to tag the DNA bases.
The same technique could be used to detect genes with one incorrect DNA base that cause cystic fibrosis and certain types of cancer. Experimental results indicate that a DNA sequence in a liquid sample will hybridize with a complementary DNA sequence bound to a cantilever, even if the sample sequence has one wrong base, or mismatch. Exposed to a mismatch, a cantilever will bend up instead of down; the directional change could be used to flag defective genes. Applied to prostate cancer detection, the technique has been demonstrated 10 times more sensitive than conventional methods.
The technology has been licensed to Graviton, Inc., LaJolla, CA.
Contact Thomas Thundat, Oak Ridge National Laboratory, PO Box 2008, Bldg. 4500 South, M/S 6123, Oak Ridge, TN 37831; 865-574-6201, thundattg@ornl.gov. |
