Role of Nanotechnology: Revolutionizing Latent print development

Introduction:

The ability to gather, examine, and recognize latent fingerprints plays a crucial role in forensic science when it comes to investigating crimes and bringing offenders to justice. These barely noticeable traces left at murder sites are similar to silent witnesses awaiting discovery. Latent print development has been substantially improved by technological developments over time, and nanotechnology is one of the most promising and revolutionary advancement in this area.

Latent print development now has a wider range of options because of nanotechnology, a field that studies objects with dimensions between 1 and 100 nanometers. We will examine the extraordinary effects of nanotechnology on latent print analysis in this blog, as well as its uses, advantages, and fascinating prospects.

The Basics of Latent Print Development and Nanotechnology:

Let’s first understand the basic concepts of latent print development before exploring the function of nanotechnology. Latent prints normally cannot be seen with the unaided eye and must be enhanced for accurate visualisation.

To make these prints visible in the past, several techniques including dusting, iodine fuming, and chemical reagents were employed. The usefulness of these techniques and the possible harm they could do to the evidence, however, are frequently their limitations.

Nanotechnology:

Nanotechnology is concerned with structures and materials at the nanoscale level, which is typically less than 100 nanometres in size. At this scale, materials can exhibit distinct properties and behaviours that differ from their bulk counterparts.

Fig: latent prints under different powder and  fluorescence.

Techniques Utilized to develop latent fingerprints using nanoparticles:

Multi-Metal Deposits (MMD)

• The first technique where nanoparticles were used to detect fingerprint was Multi-Metal Deposits (MMD) and it involves two processes:
• Firstly, the object would be dipped in an acid bath containing gold nanoparticles, where the gold would adhere to the raised ridges of the finger print. The object is then submerged in a solution of silver nanoparticles, where the layer of gold serves as a nucleation site for the silver to build onto, leaving a visible print.
• The gold particles can be given functional groups to improve the efficiency of this method. One intriguing example is the attachment of a particular antibody connected to nicotine to gold nanoparticles.
• During testing, it was discovered that the solution could not only successfully disclose fingerprints, but that if the person who left the prints was a smoker, the fingerprints would also illuminate under UV light. There is no reason to believe that this technique cannot be modified to include other range of drugs or other sweat-secreted compounds, even though this study specifically examined smoking.
• MMD is a very adaptable approach due to its effectiveness on both porous and non-porous surfaces as well as wet surfaces. It is limited however, by the necessity of immersing the fingerprint-covered item in an aqueous solution of gold nanoparticles. Therefore, it is useless for locating prints on surfaces like walls or floors at the crime scene or for any object that is too large to be submerged in a bath.

Dusting by Nanoparticles:

• The typical method of applying a fine dust to the area and then brushing extra dust away to leave only the particles that stick to the ridges of the print is being improved by another method that researchers are studying. Instead of the traditional micron-range sized particles, scientists are now working with dust that has nano-scale particles.
• These tests have shown that nano-dusting has the ability to create higher resolution prints on a variety of surfaces when gold is utilised as the metal for the nanoparticles.
• Tests using multiple types of nanoparticles, like zinc oxide and iron oxide, have also demonstrated the feasibility of making high resolution prints by dusting. It has been demonstrated that zinc oxide can successfully remove prints from non-porous surfaces even after the prints have been there for more than a month.

Quantum Dots:

Fig 2: The anatomy of quantum dots. (A) QDs contain a semiconducting core-shell. The surface can be coated with hydrophilic, hydrophobic, and amphiphilic ligands (common coating molecules are shown) which can be further linked with proteins, drugs, antibodies, and other compounds. (B) The emission spectra of QDs can be tuned by adjusting the size. (C) Fluorescence lifetimes of QD in comparison with other fluorophores [3].

Quantum dots are intriguing because they fluorescence under UV light and based on the size of the particles they have varying emission spectra. Commonly studied QD’s in the detection of fingerprint are derived from Cadmium Sulphide (CdS), Cadmium Selenide(CdSe) and Cadmium Telluride(CdTe).

Regarding CdTe, it is possible to make this kind of QD’s water-soluble so that it may be sprayed onto the prints in an aqueous solution. In addition, depending on the size of the particle, it can be made to fluorescence in a variety of colours.

The prints produced after rinsing the water soluble CdTe for few minutes are of high resolution than any other conventional methods.

CdTe capped with Mercaptosuccinic Acid (MSA) resulted in much shorter time in image development. Previously, CdTe QD’s required 15mins of bathing in solution to develop the prints but when the CdTe was capped with MSA It was able to prints with high resolution in a mere second than the best chemical prints developers. Future research could lead to the development of a CdTe QD spray that could be used to apply fingerprints on-scene and make them immediately visible.

Drawbacks of CdTe QD’s:

There are some significant disadvantages to CdTe and the other cadmium QDs. Cadmium is a dangerous heavy metal that should never be used, especially if it has been manufactured in spray form for use in on-scene print detection.

Recently, a solution emerged where the poisonous core is entirely replaced with non-toxic zinc sulphide (ZnS). In the research, these new QD is far effective than the chemical indicator and shows equal or high efficiency than the CdTe.

Drawbacks of ZnS QD’s:

It is naturally a shade of blue which is less visible to human unaided eye than other indicators. It lacks ability to size tune itself to different colours.

This can be corrected by doping it with copper compound, the doping will lead to red shift in the emission spectra. These copper-doped ZnS QDs tend to be effective at detecting latent fingerprints and lack the toxic properties that were a problem with the different cadmium-based QDs.

Application of Nanotechnology in Latent Print Development:

1. Powders With Nanoparticles: By adding nanoparticles to fingerprint powders, latent prints can be more easily detected and their visibility is improved without smudging.
2. Nanofibers and nanowires: These substances can be used to make brushes with nanostructures that assist in lifting and transferring latent prints to appropriate substrates without tampering with the evidence.
3. Sprays Containing Nanomaterials: Sprays containing nanomaterials in the form of aerosols can be used to detect latent prints on a variety of surfaces, including porous materials like paper and fabric.

Benefits of Nanotechnology in Latent Print Development:

1. Enhanced Sensitivity: Nanotechnology makes it possible to create extremely sensitive techniques for finding and seeing latent prints. The likelihood of a successful identification is increased by the more effective revelation of even faint or incomplete prints. This is especially useful when more conventional techniques might not yield viable prints.
2. Non-Destructive Techniques: Many nanotechnology-based techniques are non-destructive, which means they don’t damage or change the evidence. In forensic investigations, when the evidence must be maintained for court procedures, maintaining the integrity of the evidence is essential.
3. Greater Applicability: Nanotechnology-based methods are applicable to a wider variety of substrates and surfaces. They can be used on porous surfaces like paper, textiles, and even skin in addition to non-porous ones like glass and metal. This adaptability greatly broadens the range of possible evidence that can be examined.
4. Reduced Contamination Risk: Because traditional techniques frequently involve direct physical contact with the latent print, there is a potential for contamination to rise. The majority of nanotechnology-based approaches use non-contact methods like aerosol sprays or brushes with tiny features. By doing this, the likelihood of contaminating the latent print or the surrounding area is reduced.
5. Improved Imaging and Documentation: Latent prints may now be more accurately imaged and recorded because of nanotechnology. High-resolution photos can be captured using sophisticated tools and software, and they can then be digitally stored for future use and study.
6. Faster and more accurate analysis: Analysis that is quicker and more precise is frequently made possible by the sensitivity and effectiveness of nanotechnology-based techniques. This could speed up inquiries and aid law enforcement in more effectively resolving cases.

Challenges of Nanotechnology in Latent Print Detection:

While nanotechnology holds greater promise in detection of latent prints there are several challenges and considerations need to be addressed. Some of the challenges are:

1. Cost and Availability: The development and acquisition of many nanotechnology-based equipment and materials can be expensive. Certain expenses might make certain technologies less accessible, especially for smaller or underfunded forensic laboratories.
2. Specialised Training: Forensic professionals must have specialised training in order to use nanotechnology in latent print detection. They must learn effective ways to use software, hardware, and nanomaterials. This increases the adoption process’s overall expense and duration.
3. Standardisation: To maintain consistency and dependability among various laboratories, it is crucial to provide standardised techniques and guidelines for the application of nanotechnology in latent print detection. Lack of standards can produce inconsistent outcomes and make determining whether or not a piece of evidence is admissible in court challenging.
4. Nanomaterial Safety: Due to their size and characteristics, some nanomaterials may raise safety issues. When using nanomaterials, it is crucial to protect forensic experts’ safety and reduce any possible health concerns.
5. Legal and Ethical considerations: The application of nanotechnology to forensic investigations creates several legal and ethical issues. To preserve the integrity of the evidence and safeguard individual rights, concerns about chain of custody, privacy, and the possibility for technology exploitation must be addressed.
6. Equipment maintenance: The machinery used in nanotechnology is often complicated and sensitive. To guarantee reliable findings, routine calibration and maintenance are necessary. To avoid equipment breakdown and expensive downtime, labs must invest in routine maintenance.

Conclusion:

Currently, the above-mentioned techniques are not utilized in any case work and they only exist in the laboratory. Many nanoparticles can be used to detect latent fingerprints. MMD with gold and silver particles can produce very clear prints with long shelf life. Size-tunable quantum dots led to number of new techniques that are greater in resolution than the conventional method.

Increased sensitivity, non-destructive techniques, wider applicability, lower risk of contamination, preservation of evidence, quicker and more accurate analysis, and the potential for integration with other advanced technologies are among the advantages of nanotechnology in latent print development. These benefits help forensic science strengthen law enforcement organisations’ capacity to identify criminals and bring them to justice.

In conclusion, despite the fact that nanotechnology has many benefits for detecting latent prints, it is not without drawbacks. To ensure that nanotechnology is used in the field of forensic science successfully and ethically, cooperation between forensic scientists, researchers and legal experts will be necessary to overcome these challenges and advanced methods should employ keeping in mind the safety, maintenance and its standardization.

References:

1. Prabakaran, E. and Pillay, K., 2021. Nanomaterials for latent fingerprint detection: a review. Journal of materials research and technology, 12, pp.1856-1885.
2. France, J., 2014. Nano Technology and Latent Fingerprint Detection. Da Vinci’s notebook, 6.
3. Maysinger, D., Ji, J., Hutter, E. and Cooper, E., 2015. Nanoparticle-based and bioengineered probes and sensors to detect physiological and pathological biomarkers in neural cells. Frontiers in neuroscience, 9, p.480.