Nano-tags offer new hope in fight against gun crime

Research Lead

Researchers in the UK have developed a new way of tagging bullets. The tags, which are just 30 microns in diameter and invisible to the naked eye, are designed to be coated onto gun cartridges. They then attach themselves to the hands or gloves of anyone handling the cartridge and are very difficult to wash off completely.

Crucially, some of these ‘nanotags’ also remain on the cartridge even after it has been fired. This should make it possible to establish a robust forensic link between a cartridge fired during a crime and whoever handled it.

To date it has been extremely hard to establish such a link because of the difficulty in retrieving fingerprints or significant amounts of DNA from cartridge surfaces.

This development is the work of a team of chemists, engineers, management scientists, sociologists and nanotechnologists from Brighton, Brunel, Cranfield, Surrey and York universities, with funding from the UK’s Engineering and Physical Sciences Research Council.

“The tags primarily consist of naturally-occurring pollen, a substance that evolution has provided with extraordinary adhesive properties,” says Professor Paul Sermon from Surrey University, who led the research. “It has been given a unique chemical signature by coating it with titanium oxide, zirconia, silica or a mixture of other oxides. The precise composition of this coating can be varied subtly from one batch of cartridges to another, enabling a firm connection to be made between a particular fired cartridge and its user.”

In addition to this breakthrough, the team has also developed a method of trapping forensically-useful amounts of DNA on gun cartridges. It involves increasing the abrasive character of the cartridge case with micro-patterned pyramid textures, or adding an abrasive grit, held in place by a thin layer of resin, to the cartridge base.

This rough surface is able to remove and retain dead skin cells from an individual’s thumb as a cartridge is loaded into a firearm. A key benefit is affordability: there has not been a cost-effective way of reliably capturing sufficient DNA from a gun cartridge before.

The technology has been designed to avoid damage to the DNA caused by temperatures generated as the gun is fired, or when copper is extracted from the cartridge case by the lactic acid in sweat.

The nanotag and DNA capture technologies could potentially be available for use within as little as 12 months. “We’re currently focusing on understanding the precise requirements of the police and cartridge manufacturers,” comments Professor Sermon. “But our work clearly could make a valuable contribution not only to solving gun crime but also to deterring criminals from resorting to the use of firearms in the first place.”