IBM scientists have developed a
silicon-based DNA transistor, which could
generate advances in diagnosing and treating illness.
The scientists have passed DNA strands through nano-sized holes
drilled into silicon chips. The researchers in microelectronics,
physics and biology are investigating how to master the technique
that threads a long DNA molecule through a three nanometer wide
hole, known as a nanopore, in a silicon microchip. As the molecule
is passed through the nanopore, it is moved along one unit of DNA
at a time, as an electrical sensor "reads" the DNA.
IBM said the challenge in the project is to
slow
the flow 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
personalised genome analysis at a cost of $100 to $1,000. In
comparison, the first sequencing ever done by the Human Genome
Project cost $3bn.
Personalised medicine
Accessing individuals' personal genetic code could advance
personalised medicine using genetic and molecular data. This could
help determine a person's predisposition to a particular disease or
condition. It could also help to discover and trial new
medicines.
"The technologies that make reading DNA fast, cheap and widely
available have the potential to revolutionise bio-medical research
and herald an era of personalised 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."
Control rate breakthrough
Scientists worldwide have been working on using nanopore
technology to read DNA, but IBM said nobody had figured out how to
control the speed of a DNA strand as it travels through the
nanopore. Slowing the speed is critical to being able to read the
DNA strand and IBM scientists believe they have a unique
approach.
To control the speed at which the DNA flows through the silicon
nanopore, IBM researchers have developed a device comprising a
multilayer nano-structure that contains the nanopore. Voltage
biases between the electrically addressable metal layers modulate
the electric field inside the nanopore. This device uses 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 hope to move DNA through the nanopore at a rate of one
nucleotide per cycle. IBM scientists believe this rate would make
DNA readable.
So far the process has been demonstrated theoretically and
computationally. The researchers hope to demonstrate the technique
experimentally soon.
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 Autumn 2005, IBM revised its corporate privacy and equal
opportunity policies to reflect the corporation's intention to
handle information about employees' genes with a high regard for
their privacy, and to refrain from using genetic test information
to discriminate against a person in employment. The company claims
to be the first to explicitly restrict genetic data from being used
to make employment-related decisions.