Latent Fingermark Imaging by Single-Metal Deposition of Gold Nanoparticles and Surface Enhanced Raman Spectroscopy

Abstract

In forensic science, there is a high demand for a technique that allows the revelation of fingermarks invisible to the naked eye as well as the chemical information they contain. Here, we present a feasibility study consisting of using both the luminescence enhanced by surface plasmon of gold nanoparticles, and the surface enhanced Raman spectroscopy signal of fingermark chemical components to image latent fingermarks. A latent fingermark deposited on a transparent glass substrate was visually revealed using single-metal deposition employing gold nanoparticles. The resulting enhanced luminescence was monitored over a developed area of the latent fingermark, displaying light regions of 200–400 μm, corresponding to the fingermark ridges. The Raman signal of the fingermark's chemical components was enhanced into a measurable signal. Imaging those Raman peaks revealed the ridges pattern, attesting to the potential of our method. Since SMD is an end-of-sequence revelation technique for which further enhancement techniques do not exist, this work aims at demonstrating the feasibility of the technique in order to apply it on different systems, able to illuminate a complete surface of a few cm, and thus capable of both detecting contaminants in LFM and imaging features of the size of a complete LFM.

Eu-Doped Pyrochlore Crystal Nano-Powders as Fluorescent Solid for Fingerprint Visualization and for Anti-Counterfeiting Applications

“…However, at crime scenes fingerprints are not apparent to the naked eye. For this reason, they are called latent fingerprints (LFPs) and need to be made sufficiently visible with specific techniques [ 2 ] like single-metal deposition methods [ 3 ], fuming, and powder-dusting techniques [ 4 , 5 , 6 ]. The details that form the ridge pattern are called loops, arches, and whorls and are organized in different levels.…”

Visualization Detection Based on Gold Nanoparticles

“…Also, there is a so-called SMD Ⅱ method, which uses AuNPs to first deposit on the latent fingermarks and then applies AuNPs again to enhance the deposited fingermarks. G. Kolhatkar et al present SMD detection on transparent glass substrates based on trisodium citrate dihydrate synthesized AuNPs as the reagent for SMD Ⅱ [20]. They investigate the luminescence enhancement by stereomicroscopy and detect SERS whose results confirm the feasibility of the method.…”

SALDI-MS and SERS Multimodal Imaging: One Nanostructured Substrate to Rule Them Both

“…9−12 SERS is frequently used not only for body fluid analyses, such as pathogen detection (e.g., bacteria from urine and blood 11 ) but also for imaging applications such as tumor margin determination, 10 single-cell analysis, 12 and even for revealing chemical information from latent fingermarks. 9 However, sample preparation for SERS imaging using metallic nanoparticles is complicated (nanoparticles need to be functionalized with labels and binding molecules for a specific target), 13,14 while label-free experiments often experience nanoparticle surface saturation. 15 Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) is commonly used in proteomics and metabolomics studies 16 as it offers rich, high-quality spectra, with specific chemical information (such as molecular weight and isotopic pattern), and even tandem mass spectrometry information (MS2) that makes the identification of molecules possible.…”

“…Surface-enhanced Raman spectroscopy (SERS) boosts Raman sensitivity and specificity through electromagnetic enhancement provided by plasmon resonances in the metal substrate, that is, the Raman signals of molecules in the close vicinity of metallic nanostructures are amplified by several orders of magnitude, and through chemical enhancement when a charge-transfer mechanism in the metal–adsorbate complex is established . Gold and silver nanoparticles are popular for SERS detection, as they are stable in air and can be used over a wide range of laser wavelengths (400–1000 nm for Ag and 600–1200 nm for Au). − SERS is frequently used not only for body fluid analyses, such as pathogen detection (e.g., bacteria from urine and blood) but also for imaging applications such as tumor margin determination, single-cell analysis, and even for revealing chemical information from latent fingermarks . However, sample preparation for SERS imaging using metallic nanoparticles is complicated (nanoparticles need to be functionalized with labels and binding molecules for a specific target), , while label-free experiments often experience nanoparticle surface saturation …”