How green nanotechnology is transforming latent fingermarks into rich sources of forensic intelligence
In the world of crime scene investigation, a single fingerprint has long been the gold standard for placing an individual at the scene of a crime. Yet traditional methods often reveal only part of the story—the ridge patterns that identify who left the mark. What if that same fingerprint could also reveal what the person had touched, ingested, or even aspects of their lifestyle?
Focuses primarily on ridge patterns for identification purposes.
Reveals chemical composition for intelligence beyond identification.
This revolutionary possibility is now emerging through an innovative combination of green nanotechnology and advanced chemical analysis, turning latent fingermarks into rich sources of intelligence rather than just identification tools.
Recent breakthroughs in forensic science have demonstrated how greenly synthesized silver nanoparticles can work with Surface-Assisted Laser Desorption/Ionization Mass Spectrometry (SALDI-MS) to detect both endogenous and exogenous compounds in fingermarks 1 . This approach represents a significant leap beyond traditional fingerprint development methods, unlocking a wealth of chemical information while embracing environmentally friendly laboratory practices.
Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS) has been a valuable tool for analyzing biological samples, but it faces a significant limitation when studying small molecules. The organic matrices used in MALDI-MS create interfering background signals in the low molecular weight region (m/z < 700 Da), potentially obscuring important forensic evidence.
This is where SALDI-MS changes the game. By replacing organic matrices with nanostructured surfaces, SALDI-MS eliminates matrix-related interference, enabling clear detection of small molecules 2 . The technique offers minimal and predictable fragmentation patterns, high tolerance to salts, and reproducible signals—all crucial advantages for forensic applications where sample integrity is paramount.
Traditional chemical synthesis of nanoparticles often involves toxic chemicals that can leave harmful residues, posing potential risks to both users and the environment. Green synthesis approaches overcome these limitations by using natural resources like plant extracts as reducing and capping agents.
Eliminates toxic chemicals
Easier scaling for laboratory use
Reduced cluster formation
Reduced environmental impact
The shift toward green nanotechnology in forensics represents both an environmental and practical advancement, creating more sustainable laboratory practices while maintaining—and often enhancing—analytical performance.
A pioneering 2023 study published in Surfaces journal provides the first documented application of greenly synthesized silver nanoparticles for SALDI MS analysis of latent fingermarks 3 . The experimental approach combined botanical knowledge with cutting-edge analytical techniques:
Researchers created AgNPs using leaf extract from a native plant of Brazil's Cerrado biome, added to a silver nitrate solution. The synthesis occurred under dark conditions at 75°C for 150 minutes, monitored throughout by UV-Vis spectrophotometry.
The resulting AgNPs underwent rigorous analysis to determine their size distribution and stability—critical factors for their performance in SALDI-MS.
Latent fingermarks from three distinct donors were treated with either conventional α-CHCA matrix or the green AgNP suspension, then analyzed using MALDI-TOF MS equipment in the mass range of 100-1000 m/z.
The characterization results revealed AgNPs with an average hydrodynamic diameter of 25.94 ± 0.30 nm—an ideal size range for SALDI-MS applications. The nanoparticles demonstrated good stability with a Zeta potential of -33.4 ± 2.6 mV and a polydispersity index of 0.659 ± 0.085.
| Parameter | Result | Significance |
|---|---|---|
| Hydrodynamic diameter | 25.94 ± 0.30 nm | Ideal size for SALDI-MS applications |
| Polydispersity Index (PdI) | 0.659 ± 0.085 | Moderate size distribution |
| Zeta potential | -33.4 ± 2.6 mV | Good stability of nanoparticle suspension |
| m/z Value | Proposed Identity | Forensic Application |
|---|---|---|
| 106.9 | Silver cation | Internal calibrant for mass spectrometry |
| 215.8 | Silver cluster | Internal calibrant for mass spectrometry |
| 322.7 | Silver cluster | Internal calibrant for mass spectrometry |
Most significantly, the AgNP-based SALDI MS approach detected intense silver cation species at m/z 106.9, 215.8, and 322.7, which serve as important internal calibrants for mass spectrometry. The greenly synthesized AgNPs showed a relative intensity at least 20 times higher for silver ions compared to conventional AgNO3 suspension, suggesting enhanced detection capabilities for molecular species in forensic traces.
Perhaps most importantly, the method successfully detected components from both endogenous (natural skin secretions) and exogenous (external contaminants) sources in the latent fingermarks, opening new possibilities for extracting intelligence beyond mere identification.
| Material/Reagent | Function in Experiment |
|---|---|
| Cerrado biome plant extract | Green reducing and capping agent for nanoparticle synthesis |
| Silver nitrate (AgNO₃) | Precursor for silver nanoparticle formation |
| α-CHCA matrix | Conventional organic matrix for comparison studies |
| Acetonitrile (ACN) | Solvent for sample preparation |
| Trifluoroacetic acid (TFA) | Ion-pairing agent to improve analyte detection |
| MALDI-TOF MS equipment | Analytical instrument for mass spectrometry analysis |
The implications of this research extend far beyond traditional fingerprint identification. The ability to detect exogenous compounds in fingermarks opens remarkable possibilities for forensic intelligence. According to recent reviews, SALDI-MS has shown great promise for identifying:
and their metabolites
residues
and their breakdown products
that can indicate personal habits
that might reveal lifestyle patterns
This chemical profiling capability transforms fingermarks from simple identifiers into rich sources of information about the activities and characteristics of individuals involved in criminal investigations.
The application of greenly synthesized nanoparticles aligns with a broader movement toward sustainable forensic practices. As researchers continue to explore biological resources for nanoparticle synthesis, we can anticipate even more environmentally friendly protocols that maintain—and enhance—analytical sensitivity.
The marriage of green nanotechnology with advanced mass spectrometry techniques represents a significant leap forward for forensic science. SALDI-MS analysis using greenly synthesized silver nanoparticles offers a powerful tool for unlocking the chemical stories hidden within latent fingermarks—all while embracing environmentally responsible laboratory practices.
As this technology continues to develop, we stand at the threshold of a new era in forensic investigation, where a single fingerprint may reveal not just who left it, but what they touched, what they consumed, and where they've been—transforming this timeless evidence into an even more powerful witness for justice.