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Printed Electronics World
Posted on September 15, 2009 by

Ultrasensitive electronic sensor array speeds up DNA detection

Scientists at Singapore's Institute of Bioengineering and Nanotechnology (IBN), the world's first bioengineering and nanotechnology research institute, have successfully developed a novel electronic sensor array for more rapid, accurate and cost-efficient testing of DNA for disease diagnosis and biological research.
This study was published recently in a leading international chemistry journal, Journal of the American Chemical Society1.
Conventionally, human DNA is detected through the use of polymerase chain reaction (PCR), which while effective, is also expensive, cumbersome and time-consuming for widespread use. The PCR technique amplifies a single piece of DNA across several orders of magnitude, duplicating millions or more copies of a particular DNA sequence, in order to detect the genetic material more easily. Although effective, tests involving PCR may not be optimal for situations such as a pandemic outbreak, where results are needed quickly because PCR devices tend to be bulky and costly.
Called the "Nanogap Sensor Array", IBN's newly developed device has a unique, vertically aligned nanostructure design and a two-surface configuration based on electronic transduction. The sensor comes with a pair of micro-sized metal electrodes separated by a nanogap (5 - 20 nm or approximately 1/50,000 the width of a human hair). The biosensor will translate the presence of DNA into an electrical signal for computer analysis. The distinctively designed sensor chip has the ability to detect DNA more efficiently by "sandwiching" the DNA strands between the two different surfaces.
Based on laboratory results, the sensor has shown "excellent" sensitivity at detecting trace amounts of DNA.
"By saving time and lowering expenses, our newly developed Nanogap Sensor Array offers a scalable and viable alternative for DNA testing. The novel vertical nanostructure design and two different surfaces of the sensor allow ultrasensitive detection of DNA. This sensitivity is best-in-class among electrical DNA biosensors. The design of the sensor also took into consideration the feasibility of mass production in a cost-effective way for expanded usage," said Dr Zhiqiang Gao, IBN Group Leader.
Another distinctive feature of the biosensor is its ability to capture DNA strands more effectively. This is possible because the two surfaces of the sensor are coated with a chemically treated "capture probe" solution through an electrochemical technique specially developed by IBN. This allows DNA strands to "stick" more easily to the sensor, resulting in a faster and more accurate analysis.
"This new biosensor holds significant promise to speed up on-going efforts in the detection and diagnosis of debilitating diseases such as cancer, cardiovascular problems and infectious viruses. We aim to make healthcare accessible to the masses with early disease diagnosis as the critical driving force behind the research we undertake here at IBN," added Professor Jackie Y. Ying, IBN Executive Director.
A schematic illustration of IBN's Nanogap Sensor Array. There is a 5-20 nm gap or insulating layer between a pair of metal electrodes.
The sensing protocol of the device allows the DNA strands to "stick" to the two different surfaces of the sensor, which have been coated with a capture probe solution.
Reference: Singapore's Institute of Bioengineering and Nanotechnology
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