Pollen-coated bullets will help find criminals

August 2nd, 2008 - 10:54 am ICT by IANS  

London, Aug 2 (IANS) British researchers have developed a new coating for gun cartridges with pollen and grit to help identify criminals that use firearms. The new technique involves coating batches of cartridges with unique “nanotags” that are invisible to the naked eye and designed to attach to hands, gloves and clothing of anyone that handles such a coated cartridge. Some of the tags also remain on the spent cartridge casing.

The tags, developed by researchers from Brighton, Brunel, Cranfield, Surrey and York universities, could perform a similar role as the specks of explosives residue currently used to link people to guns or crimes, NewScientist reported.

The nanotags are made from pollen, and a mix of grains of crystal oxides such as zirconia, silica and titanium oxide. Using varying combinations of crystal and pollen grains, it is possible to make large numbers of unique tags.

“We decided to work with pollens because they have a unique structure, resistant to temperature and easily recognisable,” said Paul Sermon from the University of Surrey, who led the research. “It’s also easily dispersed and carried around in clothes, skin, etc.”

Pollen grains vary between plant species and are easily identified under a microscope. Chemical techniques could reveal which oxides were mixed with the pollen, and in which proportions to work out which batch of cartridges they originated from.

“The most challenging part of the project was nanoengineering a coating robust enough to withstand the high temperatures of firing and that would still release the tags when touched,” he added.

The researchers are also working on a way to have gun cartridges retain skin cells from anyone who handles them, for subsequent DNA-based forensic analysis. Micro-scale grit can effectively trap cells and protect DNA from the heat of firing.

Currently used cartridges are smooth and rarely retain DNA or fingerprints.

The team is also looking to apply the technique to knives so that these may retain DNA more reliably.

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