Scene-of-the-crime DNA analysis is moving a step closer

Dec 4 2004

Scene-of-the-crime DNA analysis is moving a step closer to reality with the development of new gene-testing technology at The University of Auckland.

Currently DNA analysis is both time-consuming and expensive, but researchers at the Polymer Electronics Research Centre (PERC), within the Faculty of Science and the Faculty of Medical and Health Sciences, hope to change that by inventing a system that provides direct, real-time detection of DNA.

"Our ultimate goal is to devise a gene sensor system forensic scientists can take out into the field that is so sensitive it can work with minute amounts of DNA very quickly," says the Director of PERC, Dr Jadranka Travas-Sejdic.

To achieve this, the researchers plan to cut out a step in the procedure - the requirement for labeling samples with fluorescent tags before DNA testing.

"Our technology will be based on combined direct electrical and optical signal read-outs, with no need to label samples. By attaching or 'entrapping' gene probes into conducting polymers, changes in those materials will tell us when we have a DNA match," says Dr Travas-Sejdic.

The DNA analysis research is supported by a prestigious Marsden Fund grant, awarded to Dr Travas-Sejdic and her colleague, Dr Christian Soeller, for their work on a new generation of opto-electronic biosensors. Associate investigators are Professor Ralph Cooney of The University of Auckland and Dr Gerard Bidan, French Atomic Commission (CEA) in Grenoble.

In addition to forensic science, the research will also have applications in medical diagnostic testing, bioresearch and the food industry.

The development of the new generation of biosensors is based on "intrinsically conducting polymers" - a novel class of organic material that can conduct an electrical current - and "quantum dots." Quantum dots are tiny, nanometer-sized crystals with optical properties, which absorb a specific color of light based on their size.

Because of their optical and electronic properties, the conducting polymers and quantum dots interact in a specific way. The researchers are studying how these new composite materials alter in the presence of complementary gene fragments.

Dr Soeller says the sensor type has the potential to be a major advance over current technology.

"The current challenge is to improve sensitivity to match and supercede that of the old time-consuming methods. The result will be faster diagnosis using a more flexible sensor that has minimal environmental impact."