Video: DNA reader leads way in medical advances

IBM scientists have developed a silicon-based DNA transistor, which could generate advances in diagnosing and treating illness.

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.

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