Plants help to fight gun and kife crime

Researchers working at the University of Surrey are developing ways to mark weapons with Lily pollen. By mixing the pollen of Lilium longiflorum with a polymer they can create a 'nanotag'.
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.

The pollen is invisible to the naked eye, but rubs off onto hands and clothing, marking the user. It is very difficult to wash off and does not degrade over time. This makes it perfect for establishing a proven link between an individual and weaponry found at a crime scene.