Electric Sensor Detects DNA for Disease Diagnosis

A newly developed electrical DNA biosensor will help to characterize pathogens and measure mRNA levels during expression profiling. It will be suitable for point-of-care (POC) diagnosis and criminal investigations.

Scientists in Singapore developed the new electronic sensor that will offer a faster, less expensive, and more practical alternative to tests now used to detect DNA. The new lab-on-a-chip test will lead to wider, more convenient use of DNA testing.

Zhiqiang Gao, Ph.D., at the Institute of Bioengineering and Nanotechnology (IBN; Singapore) and colleagues developed a nanogap sensor. They used a pair of micro-sized metal electrodes separated by a nanogap, 1/50,000 the width of a human hair, in combination with special chemical probes to capture tiny segments of DNA. The newly formed circuit then translated the presence of DNA into an electrical signal that that was measured by a computer. In laboratory tests, the sensor showed excellent sensitivity at detecting trace amounts of human DNA.

Another feature of the biosensor was its ability to capture DNA strands more effectively. The two surfaces of the sensor were coated with a chemically treated capture probe solution through an electrochemical technique specially developed by IBN. This allowed DNA strands to stick more easily to the sensor, resulting in a faster and more accurate analysis.

Current methods for detecting DNA use the polymerase chain reaction (PCR), which amplifies trace amounts of DNA, making it easier to detect the genetic material. The amplification step is one of the reasons why PCR tests can be expensive, cumbersome, and imprecise. The newly developed biosensor should eliminate the need for DNA amplification altogether.

"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," said Jackie Y. Ying, Ph.D., executive director of IBN.

The study was published in the September 2, 2009, issue of the Journal of the American Chemical Society.

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