Handheld DNA detector

March 10, 2008

A researcher at the National University at San Diego has taken a mathematical approach to a biological problem - how to design a portable DNA detector. Writing in the International Journal of Nanotechnology, he describes a mathematical simulation to show how a new type of nanoscale transistor might be coupled to a DNA sensor system to produce a characteristic signal for specific DNA fragments in a sample.

Samuel Afuwape of the National University, in San Diego, California, explains that a portable DNA sequencer could make life easier for environmental scientists testing contaminated sites. Clinicians and medical researchers too could use it to diagnose genetic disorders and study problems in genetics. Such a sensor might also be used to spot the weapons of the bioterrorist or in criminal forensic investigations.

The earliest DNA biosensors used fluorescent labels to target DNA, but these were expensive and slow. The next generation used mediator molecules to speed up the process and labeled enzymes to make the sensors highly selective for their target molecules. None of these systems were portable, however, and the current research trend is towards systems that use no molecular labels and have avoid costly reagents.

Nevertheless, DNA biosensors are already becoming ubiquitous in many areas, but the instrumentation is usually limited to the laboratory setting. Afuwape says that a commercially viable, off-the-shelf handheld DNA biosensor that could be used in environmental, medical, forensics and other applications might be possible if researchers could unravel the basic molecular machinery operating at the interface between sample and detector.

Afuwape suggests that a new type of electronic device, the ion-selective field-effect transistor (ISFET), might be integrated into a DNA biosensor. Such a sensor would be coated with thousands of known DNA sequences that could match up - hybridize - with specific DNA fragments in a given medical or environmental sample.

The key to making the system work is that the ISFET can measure changes in conductivity. Constructing a sensor so that the process of DNA hybridization is coupled to a chemical reaction that generates electricity would produce discrete electronics signals. These signals would be picked up by the ISFET. The characteristic pattern of the signals would correspond to hybridization of a known DNA sequence on the sensor and so could reveal the presence of its counterpart DNA in the sample. Afuwape's mathematical work demonstrates that various known chemical reaction circuits involving DNA could be exploited in such a sensor.

"The ISFET is proving to be a powerful platform on which to design and develop selective, sensitive, and fast miniature DNA sensors," says Afuwape, "such portable DNA sensors will find broad application in medical, agriculture, environmental and bioweapons detection."

Source: Inderscience Publishers

Explore further: Graphene sensors detect HIV DNA

Related Stories

Graphene sensors detect HIV DNA

October 27, 2017

Leiden and Jülich researchers discovered an elegant and simple approach to improve the sensitivity of graphene biosensors. These so-called 'next generation graphene electronic biochemical sensor devices' are able to detect ...

Recommended for you

The microscopic origin of efficiency droop in LEDs

November 21, 2017

Light-emitting diodes—or LEDs, as they are commonly known—have been slowly replacing incandescent light bulbs in applications ranging from car taillights to indicators on electronics since their invention in the 1960s.

Borophene shines alone as 2-D plasmonic material

November 20, 2017

An atom-thick film of boron could be the first pure two-dimensional material able to emit visible and near-infrared light by activating its plasmons, according to Rice University scientists.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.