Methods to detect the presence of specific DNA molecules have been around for a long time. However, they are slow, expensive and not particularly easy to transport. Although we have heard of particularly avid scientists carrying around PCR machines in their luggage, Samuel Afuwape of National University at San Diego thinks that an ion-selective field-effect transistor might take up a bit less room in our suitcase:
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."
Press Release: Handheld DNA detector
Abstract: Analytical simulation of interfacial DNA hybridisation for design of an optimal nanotechnology handheld biosensor
Image credit: Wellcome Images: Plasmid DNA on a mineral sheeet