Fingerprints to reveal drug use.

• Position: Forensics

In order to arrest a culprit, police look for fingerprints at the scene of a crime. Magnetic powder is applied to the surfaces of objects with a brush to make these prints visible. It now may be possible to use fingerprints to detect the use of drugs as well. In fact, forensic scientists would not even have to change the magnetic brush technique they have used since the 1960s: British scientists at the University of East Anglia, Norwich, and King's College, London, have developed a process based on magnetic particles and antibodies that causes fingerprints to fluoresce if they were made by a drug user.

Components of drug metabolites can be detected in sweat. "This also works for the tiny amounts of sweat left behind in the characteristic pattern of grooves and ridges of fingerprints found on objects that were touched," explains David A. Russell, an analytical bionanotechnology researcher at the University of East Anglia. To do this, Russell and his team used specially coated magnetic particles with antibodies attached. The antibodies bind specifically to drug components or metabolites. Fingerprints of volunteer test subjects from drug clinics were dusted with this magnetic powder. The prints then were treated with a solution containing an antibody bound to a fluorescing dye. This second antibody binds to the first. If the fingerprint was made by a drug user, it turns yellowish brown. Under...