In an effort to build a nanoscale DNA sequencer, IBM scientists
are drilling nano-sized holes in computer-like chips and passing DNA strands
through them in order to read the information contained within their genetic
code.
This advanced research effort to demonstrate a silicon-based
“DNA Transistor” could help pave the way to read human DNA easily and quickly, generating
advancements in health condition diagnosis and treatment. The challenge
in the effort is to slow and control the motion of the DNA through the hole so
the reader can accurately decode what is in the DNA. If successful, the
project could improve throughput and reduce cost to achieve the vision of
personalized genome analysis at a cost of $100 to $1,000. In comparison, the
first sequencing ever done by the Human Genome Project (HGP) cost $3 billion.
This illustration shows a strand of DNA traveling through a nanopore. With IBM's approach, some layers periodically stop the DNA strand while another measures its properties to determine its genetic information. (Credit: IBM)
Having access to an individual’s personal genetic code could
advance personalized medicine by using genomic and molecular data to facilitate
the discovery and clinical testing of new products, and help determine a
person's predisposition to a particular disease or condition.
A team of IBM scientists from four fields – nanofabrication,
microelectronics, physics and biology -- are converging to master the technique
that threads a long DNA molecule through a three nanometer wide hole, known as
a nanopore, in a silicon chip. A nanometer is one one-billionth of a meter or
about 100,000 times smaller than the width of a human hair. As the molecule is
passed through the nanopore, it is ratcheted one unit of DNA at a time, as an
electrical sensor “reads” the DNA. This sensor that identifies the genetic
information is the subject of intense ongoing research. The information
gathered from the reader could be used to gain a better understanding of an
individual’s medical makeup to help further the pursuit of personalized
healthcare.
“The technologies that make reading DNA fast, cheap and
widely available have the potential to revolutionize bio-medical research and
herald an era of personalized medicine,” said IBM Research Scientist Gustavo
Stolovitzky. “Ultimately, it could improve the quality of medical care by identifying
patients who will gain the greatest benefit from a particular medicine and
those who are most at risk of adverse reaction.”
IBM Research is working to optimize a process for
controlling the rate at which a DNA strand moves through a nano-scale aperture
on a thin membrane during analysis for DNA sequencing. While scientists around
the world have been working on using nanopore technology to read DNA, nobody
has been able to figure out how to have complete control of a DNA strand as it
travels through the nanopore. Slowing the speed is critical to being able to
read the DNA strand. IBM scientists believe they have a unique approach that
could tackle this challenge.
To control the speed at which the DNA flows through the
microprocessor nanopore, IBM researchers have developed a device consisting of
a multilayer metal/dielectric nano-structure that contains the nanopore.
Voltage biases between the electrically addressable metal layers will modulate
the electric field inside the nanopore. This device utilizes the interaction of
discrete charges along the backbone of a DNA molecule with the modulated
electric field to trap DNA in the nanopore. By cyclically turning on and off
these gate voltages, scientists showed theoretically and computationally, and expect
to be able prove experimentally, the plausibility of moving DNA through the
nanopore at a rate of one nucleotide per cycle – a rate that IBM scientists believe
would make DNA readable.
A human genome sequencing capability affordable for
individuals is the ultimate goal of the DNA sequencing and is commonly referred
to as “$1,000 genome.”
In the Fall of 2005, IBM revised its corporate privacy and
equal opportunity policies to reflect the corporation's intention to handle
information about an employee's genetics with a high regard for its privacy,
and also to refrain from using genetic test information to discriminate against
a person in the employment context. At that time, IBM was arguably the
first company in the world to restrict genetic data from being used to make
employment-related decisions.
On May 21, 2008, the United States signed into law the
Genetic Information Nondiscrimination Act (GINA) that protects Americans
against discrimination based on their genetic information when it comes to health
insurance and employment. The bill passed the Senate unanimously and the House
by a vote of 414 to 1. The long-awaited measure, which has been debated in
Congress for 13 years, is helping to pave the way for people to take full
advantage of the promise of personalized medicine without fear of discrimination.
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SOURCE: Wired