News from the department of forensic fingerprinting. Scientists venture beyond the mere identification of a person from the unique fingerprint pattern left on an object and move towards identifying the person by the chemistry of the patterns themselves.
After all, what can be observed as a print basically is sweat deposited by the owner and chemicals detected in it can reveal the owners lifestyle. In 2007 Russel (Leggett et al. DOI) devised a method to detect the nicotine metabolite cotinine in a fingerprint. In this way if the fingerprint does not match with a known individual at least you can be certain it is a smoker.
The method used hinges on gold nanoparticles which are coated first with a certain protein and then with a anti-cotinine antibody. A glass slide with a fingerprint on it is then immersed in a solution of these nanoparticles, the slide is then rinsed to wash of unreacted solution , then a second solution is added containing an antibody with a fluorescent dye attached. In the Russel experiment only fingerprints from a smoker yielded fluorescent images.
In a new adaptation Spindler et al. (2011, DOI) target L-amino acids. Main objective: visually enhance fingerprint traces. Rationale: amino acids are always present in fingerprints while existing methods rely on chemicals not always present. Opportunity: co-author Hofstetter in 1998 invented the required antibodies (DOI). Results: conventional methods do a better job with fresh fingerprints but the new method has merit when it comes to aged fingerprints. As a by-catch the method turns out to be selective for test subjects with a phenylalanine-sweetened chewing gum habit.