Forensics: Bullets tagged with pollen could help solve gun crimes/ Guardian, 6 August 2008
http://www.guardian.co.uk/science/2008/aug/06/gun.crime?gusrc=rss&feed=uknews
"Pollen could be used to identify the perpetrators of gun crimes, thanks to developments in nanotechnology. The microscopic grains can be coated onto bullets during manufacture and are sticky enough to hold on even after the gun has been fired. Each 'nanotag' is made up of pollen and a unique chemical signature that can be used to identify the batch of ammunition."