Handheld DNA detector

Mar 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: Physicists create new nanoparticle for cancer therapy

add to favorites email to friend print save as pdf

Related Stories

Ten more years for the ISS

Feb 17, 2014

A lot can happen in 10 years. Over the past decade an international laboratory, widely known but often under-appreciated, has been producing results at an extraordinary rate. Using its unique capabilities,

Recommended for you

Thinnest feasible nano-membrane produced

10 hours ago

A new nano-membrane made out of the 'super material' graphene is extremely light and breathable. Not only can this open the door to a new generation of functional waterproof clothing, but also to ultra-rapid filtration. The ...

Wiring up carbon-based electronics

12 hours ago

Carbon-based nanostructures such as nanotubes, graphene sheets, and nanoribbons are unique building blocks showing versatile nanomechanical and nanoelectronic properties. These materials which are ordered ...

User comments : 0

More news stories

Thinnest feasible nano-membrane produced

A new nano-membrane made out of the 'super material' graphene is extremely light and breathable. Not only can this open the door to a new generation of functional waterproof clothing, but also to ultra-rapid filtration. The ...

Wiring up carbon-based electronics

Carbon-based nanostructures such as nanotubes, graphene sheets, and nanoribbons are unique building blocks showing versatile nanomechanical and nanoelectronic properties. These materials which are ordered ...

Hackathon team's GoogolPlex gives Siri extra powers

(Phys.org) —Four freshmen at the University of Pennsylvania have taken Apple's personal assistant Siri to behave as a graduate-level executive assistant which, when asked, is capable of adjusting the temperature ...

Better thermal-imaging lens from waste sulfur

Sulfur left over from refining fossil fuels can be transformed into cheap, lightweight, plastic lenses for infrared devices, including night-vision goggles, a University of Arizona-led international team ...