Light It Up: A Nanotechnology Approach for the Acquisition of Forensic Evidence

Imagine you are watching a crime-solving TV programme. The forensic scientists have found a pair of jeans at a crime scene. They spray them with a solution, shine their 'torches' and, hey presto, blood, semen and saliva show up as brightly glowing spots each of a different colour. The scientists are able to identify what is present and then take a sample of each body fluid separately to obtain the DNA profile of the person who deposited each fluid. Is this reality? No. Far from it. Currently, a different analysis (each requiring different chemicals and equipment) is carried out to detect and identify each of these body fluids. This is very time consuming - an important factor when police are waiting for results which may help them solve a crime. The current methods also struggle to detect small traces of body fluids. Given that it is now possible to obtain a DNA profile from a single cell, collecting traces of DNA at crime scenes is vital.Our proposed research aims to make TV fiction a reality by producing a solution which, when sprayed on items of forensic evidence, will cause any traces of blood, semen or saliva to fluoresce, so that forensic scientists are readily able to identify where the body fluids are located (and, importantly, which ones are present) so that they can remove them for DNA profiling. 'Light It Up', as our solution is called, is based on minute particles called nanoparticles. Each nanoparticle will be coated with antibodies (biological molecules which recognise and bind to another partner molecule) which will specifically bind to only one body fluid. The antibodies will have fluorescent tags on them so that when specialist forensic light sources are shone on the item, the area where the body fluids are located will fluoresce with different colours, each colour representing a particular target fluid. For example, semen will show up as blue, saliva as green and blood as red. Knowing which body fluid is present can provide vital corroborative evidence for police investigations helping to support or refute suspect, victim or witness statements. 'Light It Up' will readily provide this information. As our technology uses nanoparticles, we can exploit certain size scale properties to improve the detection sensitivity of 'Light It Up'. In the presence of a magnet, iron nanoparticles are magnetic. Hence, if the nanoparticles are not bound to a biological fluid they can be simply removed using a magnet. With non-bound particles of 'Light It Up' removed, the bound particles will show up much more readily. We also aim to develop a solution of 'Light It Up' which will detect DNA directly in situ. It's the DNA that forensic scientists are really looking for when they search for biological fluids (although they also want information on the type of body fluid to help the police in their investigations). Finally, we wish to determine whether we can use 'Light It Up' to provide the police with information which can guide them in their investigations. For example, we want to establish whether we can detect explosive residues in fingerprints left at a crime scene and, for drugs and drug metabolites, in both fingerprints and body fluids. Our antibody-nanoparticle technology will specifically bind to such targets giving a fluorescent signal enabling the Police to focus their search for people handling explosive materials or dealing and/or using drugs respectively. Such information would undoubtedly help point the police in the right direction for their investigations.