Spotting Chemicals

The tips of our fingers aren’t the only places we carry a fingerprint. Chemical splodges on our skin create unique, but invisible, patterns. A new technique called molecular cartography maps these chemicals in 3D – it works on entire human bodies, but equally on plants, and on surfaces like this ATM keypad. Swabs from this man’s fingers and each of the keypad keys were analysed for traces of urocanate, a natural chemical which protects skin from UV damage. Chemicals are fleeting – they naturally decay, or rub away, but this chemical detective work paid off. There is a strong trace of urocanate on the fingertips (red), and a weaker trace on some of the keys (yellow and orange), allowing the man’s PIN to be worked out (8-0-1-7). Molecular cartography has a bright future in forensics, agriculture and medicine, where invisible bacterial traces could be followed to a source of infection.

Written by John Ankers

John Ankers

Writer

A former researcher in systems biology, John is now an online biology tutor and professional coach supporting the wellbeing of scientists and NHS professionals. He's writing, too, of course.

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• Image from work by Ivan Protsyuk, Alexey V Melnik & Louis-Felix Nothias, and colleagues
• Structural and Computational Biology, EMBL, Heidelberg, Germany and Collaborative Mass Spectrometry Innovation Center, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA, USA
• Image copyright held by the original authors
• Research published in Nature Protocols, December 2017