Micro-Swab enables DNA evidence

October 26, 2016

A new DNA extraction technology developed in South Australia has the potential to become a powerful forensic tool for criminal investigations.

DNA technology

Featured image above: prototype of the Micro-Swab, a new DNA technology. Credit: Flinders University

The pen-like device is set to help forensic experts extract relatively large amounts of DNA evidence from previously challenging surfaces.

Micro-Swab was developed by researchers at Flinders University in Adelaide, South Australia, and uses fibres soaked in a surfactant to bind to the DNA in fingerprints.

The fibres are attached to a flexible pen-like device, which allows police to obtain genetic material from hard-to-reach surfaces such as gun triggers, ammunition cartridges and the spaces between keys on computer keyboards.

According to a study on its effectiveness published in National Center for Biotechnology Information, the device extracts about 60 per cent more DNA than conventional methods and only takes about 30 seconds to swab, compared with a few hours for current methods.

Micro-Swab lead researcher Professor Adrian Linacre says DNA profiling is essential for building criminal prosecutions. He says the new device will reduce cases of inadmissible evidence.

“Currently only about seven per cent of touch DNA worldwide generates a meaningful profile,” Linacre says.

“That extraction process, even using the best methods, loses about 75 per cent of DNA and if you start off with only enough DNA to start a profile that leaves you with almost nothing.

“It was to the point where police said they no longer bothered trying to test for DNA because it didn’t work. But this is an effective way of building a profile in a single go.”

Linacre says it will not only be effective in obtaining more biological material, it will also reduce the chance of contamination.

The Micro-Swab includes a PCR tube filled with a detergent attached to the head, similar to a cap on a pen.

During extraction, the tube is removed and the fibres rub over the fingerprint, picking up substantial amounts of biological material.

The head is ejected back into the tube using a small piston at the rear of the device and then the tube, which still has residual amounts of the surfactant, is sealed and ready for quantitative PCR.

The standard process for DNA extraction begins with a foam or cotton extraction and takes about two hours before it is taken to the lab.

“We found that if you had the swab moisturised with one per cent Triton-X, a surfactant, that helps encourage the DNA to come off,” Linacre says.

“The downside to this is that you can’t repeat the test but because it is more accurate than doing the normal method, you are far more likely to get something substantial.”

DNA from fingerprints, known as touch DNA, remains the most common type of forensic evidence used in convictions. However, these methods have not been modified in decades and there have been numerous cases of insufficient or false DNA profiling because of inadequate testing or clinical errors.

Linacre says the Micro-Swab will increase the reliability of touch DNA profiling and is also capable of collecting DNA from hair follicles.

He says the device is simple to manufacture and could be 3D printed to increase availability worldwide.

The new DNA technology is expected to be launched in mid-2017.

This article on the new DNA technology Micro-Swab was first published by The Lead on 24 October 2016. Read the original article here.

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