Nanoparticles reveal the secrets of the criminal




A group of researchers from Switzerland shed light on the exact mechanisms responsible for the impressive ability of nanoparticles are used to detect fingerprints left at the crime scene. Job was published in the journal Nanotechnology, and its main motive – challenging the conventional theory that the nanoparticles are attracted to the fingerprint Finger electrostatically.

Scientists argue that the attraction was in fact caused by the chemical nature and compounds on the surface of the nanoparticles that bind to a complex cocktail of compounds present in a fingerprint.

They also believe that a more fundamental understanding of the interaction of nanoparticles and fingerprints will contribute to the development of more accurate methods that will increase the chances of finding previously undetected fingerprint. In fact about 50% of the prints left on paper, can not be found.

Lead author Sebastian Moret says: “There are a number of different methods used for the visualization of fingerprints when they were brought into the laboratory, but they all do not have enough sensitivity. Some of these techniques are joined not only to fingerprints but also to the substrate or surface on which they remain, which leads to a background that obscures fingerprints. ”

Most of these methods have been developed by trial and error, so it is very important to understand the fundamental mechanisms that stand behind them.

Fingerprints left at the scene due to natural selection – the sweat and fat compounds, as well as cosmetics like dirt or blood, which accumulate on the fingers. That’s all it creates an impressive pattern of lines that leave our fingers on the concrete surface.

In their study, the researchers of the University of Lausanne applied fingerprints on aluminum foil, and then it was immersed in an aqueous solution with silica nanoparticles, which were coated with a carboxyl group of carbon, hydrogen and oxygen.

Also nanoparticles introduced a special dye, so they can be visualized in a certain light.

Scientists have conducted a series of tests to show that the attraction between the nanoparticles and fingerprints due to the chemical bond between the carboxyl group and a specific chemical group – amines, which are present in the amino acids and proteins in a fingerprint.

Until now, the generally accepted theory was that the acidic solution, which housed the nanoparticles led to the fact that the fingerprint becomes positively charged and attracts negatively charged nanoparticles.

Nanoparticles used in criminology, not only due to the small size and optical properties, but also by the ability fine tune the surface properties, which are thought to have after them receive considerable development work.

“Now, when it is determined that chemical interaction occurs between the nanoparticles and certain chemical groups in the fingerprint, this reaction may be further increased, leading to a more accurate analysis, increased selectivity and reduced background noise.”

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