Researchers from Arizona State University’s Biodesign Institute and IBM's T.J. Watson Research Center say they have developed a prototype DNA reader that could make whole genome profiling an everyday practice in medicine.
“Our goal is to put cheap, simple, and powerful DNA and protein diagnostic devices into every single doctor's office,” said Stuart Lindsay, Ph.D., an ASU physics professor and director of Biodesign’s Center for Single Molecule Biophysics.
Such technology, which could help usher in the age of personalized medicine, where information from an individual's complete DNA and protein profiles could be used to design treatments specific to their individual makeup, is needed to make genome sequencing a reality, added Dr. Lindsay. The current hurdle is to do so for less than $1,000, an amount for which insurance companies are more likely to provide reimbursement.
In their latest research advance, the team fashioned a tiny, DNA reading device thousands of times smaller than the width of a single human hair. The device is sensitive enough to distinguish the individual chemical bases of DNA when they are pumped past the reading head. Proof-of-concept was demonstrated, by using solutions of the individual DNA bases, which gave clear signals sensitive enough to detect nanomolar amounts of DNA, reportedly even better than today’s next-generation DNA sequencing technology.
To construct their device the scientists made a “sandwich” composed of two metal electrodes separated by a two-nanometer thick insulating layer, made by using a semiconductor technology called atomic layer deposition. Then a hole is cut through the sandwich: DNA bases inside the hole are read as they pass the gap between the metal layers.
“The technology we've developed might just be the first big step in building a single-molecule sequencing device based on ordinary computer chip technology,” continued Dr. Lindsay. “Previous attempts to make tunnel junctions for reading DNA had one electrode facing another across a small gap between the electrodes, and the gaps had to be adjusted by hand. This made it impossible to use computer chip manufacturing methods to make devices.”
When a current is passed through the nanopore, as the DNA passes through, it causes a spike in the current unique to each chemical base (A, C, T or G) within the DNA molecule. Dr. Lindsay said the team encountered considerable device-to-device variation, so calibration will be needed to make the technology more robust. And the final big step of reducing the diameter of the hole through the device to that of a single DNA molecule has yet to be taken.
The research team is also working on modifying the technique to read other single molecules, which could be used in an important technology for drug development.
