Joined: 16 Mar 2004
|Posted: Fri Oct 05, 2007 1:51 pm Post subject: Nanotechnology reveals fingerprints
|Nanotechnology reveals fingerprints
by Vikki Chapman
Hidden fingerprints can now be revealed quickly and reliably thanks to two developments in nanotechnology.
The current way of revealing hidden prints involves coating the marked surface with a watery suspension of gold nanoparticles, stabilised by citrate ions. Under acid conditions, the gold particles stick to the positively-charged molecules in the fingerprint. The print is then developed with a solution of silver ions, which undergo a chemical reaction to leave an outline of dark silver metal along the characteristic ridges of the fingerprint. But the gold solution is quite unstable, and the technique is difficult to reproduce from one test to another.
Now, Daniel Mandler, Joseph Almog and co-workers at The Hebrew University of Jerusalem, Israel, have replaced the traditional gold solution with a more stable equivalent. Their gold nanoparticles bristle with long hydrocarbon chains and are suspended in petrol ether. They stick to the fingerprint residues through hydrophobic interactions, and can be developed with silver as before, producing high quality prints after just three minutes immersion time.
The team has also developed a fingerprinting method for non-porous surfaces, using a petrol ether suspension of cadmium selenide/zinc sulphide nanoparticles stabilised by long chain amines. As with the team's gold solution, the nanoparticles adhere to the fingerprint by hydrophobic interactions. But in this case, as the nanoparticles fluoresce under UV light to reveal clear fluorescent prints, no additional developing stage is needed.
Claude Roux, director of the Centre for Forensic Science at the University of Technology, Sydney, Australia, said that the use of 'nanotechnology in the fingerprint community...can bring novel and practical solutions to develop and enhance latent fingermarks...that would otherwise remain undetected.'
The simple synthesis that the scientists have developed is adaptable so different amounts of magnetic iron oxide can be used. The size and chemical properties of the pores in the particles can also be adjusted for different medical uses.
Sources: Chemistry World & Nanowerk.com http://www.nanowerk.com/news/newsid=1604.php
Story first posted: 13th March 2007.