Scientists have developed a forensic spray that uses a protein found in jellyfish that shows fingerprints within 10 seconds.
They say the dye spray can make forensic investigations faster and more efficient. It is also water-soluble and has low toxicity: traditional forensic methods use either toxic powders that can harm DNA evidence or petrochemical solvents that are bad for the environment, the sale of which is increasingly restricted.
The dyes in the spray are based on a fluorescent protein found in jellyfish called green fluorescent protein (GFP), which previously revolutionized scientists’ ability to visualize biological processes in cells and animals. The dyes are biologically compatible and do not interfere with subsequent DNA analysis of the fingerprints.
“This system is safer, more sustainable and works faster than existing technologies, and can even be used on fingerprints that are a week old,” said Prof Tony James, a chemist at the University of Bath and a co-author of the research.
The team created two different dyes, called LFP-Yellow and LFP-Red, that bind to chemicals found in sweat and oils in the skin. This locks the dye molecules in place and they emit a fluorescent glow that can be seen under blue light.
“Having two different colors available means that the spray can be used on different colored surfaces. We hope to produce more colors in the future,” said James.
The fine spray prevents splashes that can damage prints, is less messy than a powder and works quickly even on rough surfaces where it is more difficult to capture fingerprints, such as brick.
Fingerprints still account for more identification than DNA evidence in cases where the suspect is unknown, and the technology is fast and cheap compared to DNA profiling. However, governments are increasingly restricting the use of solvents used in fingerprint detection methods, including per- and polyfluoroalkyl substances (PFAS), sometimes known as “forever chemicals”.
The GFP protein is produced naturally in the North American jellyfish Aequorea victoria (sometimes called the crystal jellyfish), and emits a green glow when it absorbs blue light. Scientists are not sure what purpose the fluorescence serves for the jellyfish, but one possibility is that it helps scare away predators.
The protein is already widely used in biological research because the GFP gene can be used as a harmless glow-in-the-dark marker to detect activity in cells in laboratory dishes or inside living creatures. Flatworms, tadpoles and zebrafish have all been reprogrammed with the GFP gene.
Prof. Chusen Huang, from Shanghai Normal University in China and the lead investigator of the project, said: “We hope this technology can really improve the detection of evidence at crime scenes.”
The team is now working with companies and hopes to make the forensic dyes commercially available. Their study was published in the Journal of the American Chemical Society.
