Credit: © 2007 Wiley

The ability to identify an individual on the basis of the unique patterns that make up their fingerprints is still at the forefront of modern forensic science. Now, researchers in the UK at the University of East Anglia and King's College London have coupled fingerprinting with the ability to detect specific chemical compounds in a method that could be used as a quick screen for drug use.

David Russell and co-workers1 coated 16-nm-diameter gold nanoparticles with multiple copies of an antibody that recognizes and binds cotinine — a metabolite of nicotine. Fingerprints collected on glass slides were incubated with the modified nanoparticles and then washed to remove any unbound material. These samples were treated with a second set of antibodies — labelled with either red or green fluorescent tags — that bind to any nanoparticle conjugates left on the surface. Fluorescence images of fingerprints taken from a smoker were well-resolved with a very high degree of detail, whereas prints obtained from a non-smoker did not fluoresce at all.

When the experiment was repeated in the absence of gold nanoparticles using just anti-cotinine antibodies, poor-quality images were obtained that, despite confirming the presence of cotinine, could not be used for identification purposes. Although cotinine is used as the chemical target in this work, the ability to coat gold nanoparticles with a range of different antibodies could lead to the detection of numerous drug metabolites and simultaneously identify individuals from which the samples are taken.