Nanotechnology In Forensic Science: A Critical Overview Of Nanotechnology Applications, Nanotechnology Mechanisms And Future Directions.

1. Introduction

The detection and interpretation of the trace evidence form the basis of forensic science. Crime scene evidence is, however, limited, degraded or contaminated in most cases. Conventional methods of analysis, though more dependable, are not always sensitive enough to detect ultra-traces. Nanotechnology attempts to overcome such constraints by working with materials that have nanoscale dimensions that result in increased reactivity and signal amplification.

The nanoscale materials have a high surface-volume-area ratio, quantum confinement and optical properties which can be controlled. The aforementioned attributes render nanoparticles highly applicable in binding, detecting and amplifying forensic targets like biological molecules, chemical substances and particulate matter. In the recent ten years, interdisciplinary studies that integrate materials science, chemistry, and forensics have resulted in useful nanoscale instruments that are finding their way into laboratory processes.

2. Nanotechnology in the Detection of Latent Fingerprints.

Latent fingerprints are prints left behind on surfaces by sweat or oils, amino acids, and similar biological secretions. Traditional powders and other chemical reagents cannot be used on porous or complicated surfaces. Nanotechnology is used to increase the detection of fingerprints by interacting with nanomaterials and fingerprint residues in a specific manner.

Gold and Silver nanoparticles: Food-grade nanoparticles require decontamination to prevent contamination of food products by nano silver or nanoparticles. 

2.1 Gold and Silver Nanoparticles Gold and silver nanoparticles

To avoid contamination of food products by nanoparticle particles or Nano silver, food-grade nanoparticles must be decontaminated. AuNPs have a strong surface plasmon resonance, which enables them to generate a higher level of contrast under certain conditions concerning lighting. AuNPs are used to selectively bind proteins or lipids present in fingerprint residues with functionalization with specific ligands. Enhancement methods of silver further apply metallic silver on gold-seeded areas to increase ridge visibility.

This is an enhanced mode of resolution of difficult surfaces like polymer banknotes, wet items, and multi-coloured backgrounds. The small nanoscale size allows infiltration into microstructures without blurring the ridge structure to maintain a high level of evidence.

2.2 The Quantum Dots relate to Fluorescent Imaging.

Quantum dots (QDs) are nanocrystals of a semiconductor with high intensity fluorescence and adjustable emission wavelengths. In fingerprint examination, the QDs are bonded to sweat substances and are fluorescent under ultraviolet or special excitation sources. QDs are photostable as compared to traditional fluorescent dyes, and they generate sharper and longer-lasting signals.

Their capability to produce various colours depending on their size results in multi-wavelength imaging, which minimises the interference level of the background and maximises the clarity of the ridges. It is also applicable to overlapped prints or to patterned surfaces.

3. Forensic DNA Analysis Nanotechnology.

3.1 The magnetic nanoparticles can be used in the extraction of DNA.

DNA extraction plays a crucial role in forensic genetics, particularly when one is working with rare or degraded samples. The silica-coated or functional polymer-coated magnetic nanoparticles (MNPs) magnetically interact with DNA selectively. The purification is made easier by applying a magnetic field to separate the DNA-bound nanoparticles and the impurities.

This is a less toxic technique, shortens the extraction time, yields a higher yield, and is more reproducible than traditional protocols using centrifugation. It has been applied particularly in cases where there are skeletal remnants, burnt tissue, or samples that are exposed to the environment.

3.2 Biosensors with Nanoparticles.

The electrochemical and optical Nano sensors have the benefit of providing a high response in the detection of DNA. Glucose nanoparticle-functionalized electrodes increase signals of hybridisation, making it possible to quantify low-copy-number DNA. Such nano sensors can be built into handheld devices, which can be used to screen quickly on-site.

Carbon nanotube and graphene-based sensors also enhance electrical conductivity and signal transduction, which opens the way to the miniature forensic diagnostic platform.

4. Explosives and gunshot residue detection.

Trace explosives serve critical roles in the field of investigations of terrorism and the study of post-blast. Conventional methods of detection can involve instrumentation in the laboratory. Portable highly sensitive detection platforms are made possible through nanotechnology.

4.1 Carbon Nanotube Sensors

Carbon nanotubes (CNTs) have a high electrical sensitivity and reactivity on their surfaces. CTNT-based sensors identify nitroaromatic substances and nitrate residues in very low concentrations when they are functionalized with selective groups of chemical substances. Voltage variation in response to exposure to explosive vapour offers quick signal points of analysis.

4.2 GSR Analysis with nanoparticles.

The gunshot residue (GSR) normally consists of lead, antimony, and barium. Nanotechnology improves the scanning electron microscopy (SEM) images in terms of particle images and the characterisation of the elements. GSR particles can also be selectively bound by functionalized nanoparticles, which makes the collection and analysis of nanoparticles easier.

5. Forensic Toxicology Applications.

• Nanotechnology has enhanced the detection of drugs, heavy metals and poisons in biological fluids. Immunoassays based on nanoparticles are more sensitive to the detection of opioids, cocaine metabolites, and synthetic drugs.
• Colourimetric assays of gold nanoparticles are used to perform quick presumptive tests, as the colour of the assays changes when a particular toxin is present. In the toxicological screening of the biosensor, further enhancements in selectivity and signal amplification are realised with nanosheets of graphene oxide and a quantum dot biosensor.
• These nanoscale types of detection systems have potential uses in laboratory validation as well as in the field.

6. Nanotechnology Advantages: Underlying Mechanisms.

The forensic utility of nanomaterials is due to a number of physicochemical attributes:

• High Surface Area- High binding efficacy with trace molecules.
• Improved Optical Characteristics: Fluorescence and plasmon resonance.
• Magnetic Responsiveness- Quickly separated and purified.
• Electrical Conductivity- Enhanced transmission of signals on the sensor.
• Catalytic Activity- faster chemical reactions during detection assays.

All of these properties lead to enhanced detection thresholds and analytical reliability.

7. Restrictions and Legal Implications.

Nanotechnology in the field of forensics has high potential, but it needs to be properly validated. The cross-laboratory standardization is not very high, and before it can be used on a large scale, the reproducibility of the standard should be proven. Also, the issues related to the toxicity and environmental safety of nanoparticles should be addressed.

Legally, the evidence based on nanotechnology to be admissible must meet the scientific criteria of reproducibility, peer review, and error rate. Nanoscale processes should also be clearly articulated by experts who should be able to explain them in a way comprehensible by courts.

8. Future Directions

The nanotechnology in forensics is expected to be integrated with the following in the future:

• Portable analysis Lab-on-chip systems.
• Data interpretation through artificial intelligence.
• The microfluidic DNA and toxicology screening devices.
• Nano sensors for real-time diagnostics of crime scenes.

Due to the increase in interdisciplinary collaboration, it is possible that nanotechnology will become a standard aspect of forensic laboratories across the world.

9. Conclusion

Nanotechnology has been very important in the strength of forensic science, which has been able to improve the sensitivity, speed and precision of the analysis. Its use in the development of fingerprints, the extraction of DNA, the detection of explosives, and toxicology is an example of the potential it has to transform things. Although standardisation and acceptance by the judiciary may still be a problem, research and validation efforts are still ongoing, which shows that nanotechnology is bound to keep becoming an ever more crucial aspect of contemporary forensic investigations.