Use of Biosensors in Fingerpri...

In the forensic science field, there is an increasing need for new technologies to help and support investigators and lab scientists in pursuit of gathering all the information from evidence.

The samples of fingerprints found on the crime scene also have unique chemical contents which are used to extract important information about the person or persons of interest.

Various methods for the detection of these chemical content are currently being researched to extract information from the latent prints. These methods include spectroscopy, bio-assays/biosensors and spectrometry. 

The Biosensors and Forensic Science 

The first biosensor was invented by Clark and Lyons. 

Biosensors in forensics are ideal biological tools which can be used for quick and reliable  initial screening and testing to detect  suspicious components like biological and chemical agent in crime scenes .

Forensic science is using these biosensors for detecting the biomolecules and biological components that are being found at the crime scenes which play a great role in identifying the suspect and even reaching the criminal.

Role of Biosensors in Forensic Science

The term biosensors were coined by ‘Cammann’ and the definition was given by ‘IUPAC’.

Biosensors are those analytical devices which will convert a biological response into an electrical signal.

In forensics science, the use of different body fluids for metabolite analysis gives an alternative to the use of  DNA to avoid the backlog that occurs while DNA analysis by giving us the  worthwhile information about the suspect.

The wide use of different biomolecules in the body such as antibodies, proteins, nucleic acids, enzymes and microorganisms,  makes it possible.

The biosensors used here have great advantages such as that they are quick, little quantity of sample is required for high sensitivity, also because of their stability,  and their ability to act on the specific biomolecules has made them a very important tool for forensic analysis and detection of crime.

The enzyme which is used as a bioreceptor component in biosensors are usually proteins of oxidase type that react selectively with the specific analytes, consume dissolved oxygen and produce hydrogen peroxide which is a very easily detectable compound.

Use of Biosensors in Fingerprint Analysis

Like many other fields, biosensors also have significant and surprising applicability in the field of fingerprint examination and analysis.

By analyzing the content of a fingerprint, primarily the amino acids, we can have some understanding of who the donor of that print was and will be able to restrict the search for the investigators.

Fingerprints are one of the most important sources of information and identification and if the prints can not be utilized for their pictorial representation based on ridges and minutiae it is treated as waste evidence.

This is because of the difference in metabolites in people due to their gender, age, medications, and lifestyle.

So analyzing these biomarkers in the given fingerprint sample would allow one to gain much-needed information that will provide the investigators with proper information and will also lead to the reduction in the need to wait for the lengthy analysis of DNA that causes a backlog in the investigation.

Biosensors in Fingerprint Research

A fingerprint paper from 2015 used an enzymatic cascade utilizing L-amino acid oxidase (L-AAO) and horseradish peroxidase (HRP) in the presence of L-amino acids to produce a visible colour by oxidizing the redox dye o-dianisidine, which results in a colour that may be analyzed at 436 nm.

This is due to the fact that women produce a higher amount of these amino acids than men, therefore this allows for the determination of a person’s biological sex.  

The scientist did progress in their research in fingerprint analysis through antibodies and nanoparticles.

The researchers are studying various types of nanoparticles to visualize those latent fingerprints that are mostly being overlooked or are considered vain on the crime scene.

Gold nanoparticles are one of those types of nanoparticles which is being used to detect latent prints on paper in conjunction with cellulose interaction.

Methods used previously have proven to be unreliable and insufficient when it comes to paper surfaces with poor contrast. Therefore a new method of AuNP(Gold Nanoparticle) cellulose interaction is being studied.

Fingerprints and Nanoparticles

For the development of this method, a bifunctional compound that would bind both cellulose and the AuNPs was used to attach the AuNPs to the paper followed by an Ag-PD solution that was then added to the surface.

The solution will lead to the precipitation of black silver which gets collected on the surface covered with AuNP giving a colourless print on a coloured background.

The sebaceous content that are being present in the fingerprint will restrain the AuNP from binding and so it prevents the colouring of the print with black silver. This process is not applicable to all the fingerprints but is still being used.  

Silicon oxide particle nanoparticles can also be used for fingerprint detection. In this method, the particles were diluted using water and the sample print was dipped in the liquid by inverting the fingerprint surface.

Now the  fingerprints were left for about an hour and then tried for imaging. The fingerprint in this method got visible successfully.

We can use zinc oxide nanoparticles for the same purpose. however, this method has only been performed on non-porous surfaces and using UV light.

The prints were treated with zinc oxide nanoparticles using the small particle reagent method which involves dipping the particles in Tween 20  just before putting the fingerprints in the resulting solution.

The particle that was present on the prints were detected using luminescence. This method proved to be very effective on non-porous surfaced and very old prints.

Another method was using CdSe nanoparticles which causes the fingerprints to leave photoluminescence. Fingerprints were collected from several volunteers on different surfaces and left out to dry.

The surface containing the fingerprint was then dipped into the solution containing the CdSe nanoparticles.

After the sample was taken out from the solution of nanoparticles, it was then washed with water and was left to dry and then a UV light was used to excite the particles left on the surface.

Conclusion

The development and scientific innovation is not a new thing in science and with new innovation each day the way of forensic identification has become easier now in comparison to the dates back when forensics was just an emerging branch.

With such development and technological advancements, we are looking forward to a more futurist approach to investigation in the field of fingerprint examination and analysis.