A novel use of aptamers, or man-made chemical antibodies, has led to a world-first fingermark detection technique developed by the UTS Centre for Forensic Science (CFS) and the National Centre for Forensic Studies (NCFS) at the University of Canberra.
Led by PhD student Mike Wood, the technique represents a breakthrough for the field of forensic science, where fingerprints still play a key role in evidence collection and crime scene investigations.
“Despite the numerous advances we’ve seen in forensic science over the last 20 years, fingerprints remain a priority because they identify people, they’re a lot cheaper than many other forensic techniques, like DNA technology, and courts understand them,” Wood said.
Fingermarks contain many components, such as proteins and amino acids. Many of these components occur in very small quantities, or are sensitive to ageing or to exposure to the environment; if a mark is old or has been exposed to the elements, for example, it can be difficult to capture using traditional techniques.
Additionally, the nature of the surface on which a fingermark is found and the chemicals that exist on the surface can also impact the quality of print. As a result, effective fingerprinting techniques must be highly sensitive and must target specific components of the fingermark relative to the environment in which the mark is found.
Wood’s technique uses oligonucleotides (short strands of RNA, or single stranded DNA) to target lysozyme, a protein that is present in human sweat, and therefore in fingerprints. When the aptamer is applied to the fingerprint, its high sensitivity and selectivity properties help it bind successfully to the lysozyme without targeting the background material on which the fingermark is placed, producing a clear image. Incredibly, the whole reaction takes place in about 20 seconds.
“The thing with fingermark detection and visualisation is that you want the best contrast between the background and the ridges,” Wood said.
“This is a unique technique because of the selectivity and the sensitivity of the aptamer. You don’t need much of the lysozyme protein to be present in order for the interaction to occur and the fingermark to appear – we’re talking miniscule amounts.”
Perhaps the most exciting aspect of the work is the fact that the same technique has the potential to be applied to almost any component of a fingermark. A mark that has been exposed to water, for example, could be processed using an aptamer that targets the water insoluble components of the fingermark instead.
“Aptamers can be selected against a huge variety of targets – we chose lysozyme as a starting point, but we could have chosen any number of other targets,” Wood said.
“We think this is the starting point for a fairly massive field of research.”
This project is the latest in a series of collaborative projects between UTS and the University of Canberra, and is also the latest in a long line of exciting achievements in fingerprint research for CFS, which is emerging as an international leader in the field.
UTS researchers have also been credited with having developed a technique using antibodies to detect dry, aged and weak fingerprints; having discovered that particles in anti-fraud inks can be used in a range of fingerprinting techniques; and having developed and commercialised a thermal fingerprinting technique that has been licensed by science equipment company Foster + Freeman.