It can take days for law enforcement agencies to visualize and process a suspect’s fingerprints. Now, thanks to a protein taken from jellyfish – which in the summer months off the coast of Israel and elsewhere around the world, it can take just a few seconds. Scientists in the UK and China have developed a water-soluble, non-toxic fluorescent spray that makes forensic investigations safer, easier and quicker.
Fingerprints that are formed during an embryo’s development are unique for a particular individual; even identical twins have different fingerprints. As a result, the unique pattern of fingerprints has been used widely in forensic science for identifying individuals since the late 19th century.
Latent fingerprints (LFPs) are invisible prints formed by sweat or oil that are left on an object after finger contact. The collection of LFPs at crime scenes is an important and widely used operation in forensic science for the identification of individuals. but due to their invisible character, the search for LFPs is a significant challenge for forensic investigations – given that the rapid capture of LFPs at the crime scene is preferable, the fingerprints will fade over time.
Traditional forensic methods for detecting fingerprints either use toxic powders that can harm DNA evidence or environmentally damaging petrochemical solvents.
The new dye spray, developed by scientists at the Shanghai Normal University and the University of Bath exhibits low toxicity and enables rapid visualization of fingerprints at the crime scene.
The team published their discovery in the Journal of the American Chemical Society under the title “De Novo Green Fluorescent Protein Chromophore-Based Probes for Capturing Latent Fingerprints Using a Portable System.”
They created two different colored dyes – called LFP-Yellow and LFP-Red – that bind selectively with the negatively-charged molecules found in fingerprints, locking the dye molecules in place and emitting a fluorescent glow that can be seen under blue light.
The dyes are based on a fluorescent protein found in jellyfish, called Green Fluorescent Protein (GFP), which is used extensively by research scientists to visualize biologically compatible evidence and don’t interfere with the prints’ subsequent DNA analysis.
The fine spray prevents splashes that could damage prints, is less messy than a powder, and works quickly even on rough surfaces where it is harder to capture fingerprints like brick, said Prof. Tony James, from Bath’s chemistry department. “This system is safer, more sustainable, and works faster than existing technologies and can even be used on fingerprints that are a week old.
“Having two different colors available means the spray can be used on different-colored surfaces. We’re hoping to produce more colors in the future.”
Dr. Luling Wu, also from that university, said: “The probes are only weakly fluorescent in aqueous solution, but they emit strong fluorescence once they bind to the fingerprints through the interaction between the probes and fatty acids or amino acids.”
The principal investigator, Prof. Chusen Huang from Shanghai, said: “We hope this technology can really improve the detection of evidence at crime scenes. We are now collaborating with some companies to make our dyes available for sale. Further work is still ongoing.”