Metal oxide nanoparticles for latent fingerprint visualization and analysis of small drug molecules using surface-assisted laser desorption/ionization mass spectrometry

Abstract

We explored the applicability of different metal oxide nanoparticles (NPs; ZnO, TiO, FeO, and CeO) for the optical imaging and mass spectrometric determination of small drug molecules in latent fingerprints (LFPs). Optical imaging was achieved using a dry method-simply dusting the LFPs with a minute amount of NP powder-and still images were captured using a digital microscope and a smartphone camera. Mass spectrometric determination was performed using the NPs as substrates for surface-assisted laser desorption ionization/mass spectrometry (SALDI-MS), which enabled the detection of small drug molecules with high signal intensities. The reproducibility of the results was studied by calculating the % error, SD, and RSD in the results obtained with the various metal oxide NPs. Collectively, the findings showed that using NPs can boost the intensity of the detected signal while minimizing background noise which is an issue predominantly associated with conventional organic matrices of MALDI-MS. Among the four metal oxide NPs, utilization of the FeO NPs led to the best SALDI performance and the highest detection sensitivity for the analytes of interest. The study was then extended by investigating the influence of time elapsed since the generation of the LFP on the detection of drug molecules in the LFP. The results demonstrated that this method allows the analysis of drug molecules after as long as one week at low and intermediate temperatures (0 and 25 °C). Therefore, the SALDI analysis of small molecules using inorganic NPs, which can be implemented in forensic laboratories for screening and detection purposes, as a powerful alternative to the use of organic matrices. Graphical abstract ᅟ.

Methodologies Applied to Fingerprint Analysis

“…Francese et al explored fingerprint chemical profiles, detection, and quantification of exogenous substances, analysis of real samples and research for sustainable alternatives (). Those studies added many contributions within the fingerprint analysis, such as: the identification of blood in fingerprint samples with the differentiation of α‐hemoglobin from β‐hemoglobin (), the design of a fingerprint degradation profile on samples aged for 421 days () and the use of fingerprints as an alternative matrix in toxicological tests, comparing them with previously established matrices (blood, urine, and oral fluid) ()…”

Nanoparticles used for fingermark detection—A comprehensive review

“…Aside from these applications of metal oxide NPs for fingermark detection, there have been reports by Tianxi et al and Amin et al where they used Au NPs dotted with magnetic Fe 3 O 4 NPs or ZnO, Fe 3 O 4 , TiO 2 , and CeO 2 , respectively, to detect various drugs in fingermarks by the use of SERS or surface‐assisted laser desorption/ionization ‐ Mass spectrometry (SALDI‐MS) techniques (Amin et al, ; T. Yang et al, ). As these reports are not directly related to fingermark detection, no further detail is provided here and interested readers are directed to the cited publications.…”

“…Amin et al used four different types of metal oxide NPs-ZnO, Fe 3 O 4 , TiO 2 , and CeO 2 (Amin, Madkour, & Al-Hetlani, 2018). Sebaceous-rich fingermarks were treated and then imaged using a digital microscope and smartphone camera.…”

Complementarity of Matrix- and Nanostructure-Assisted Laser Desorption/Ionization Approaches

“…This information is used in forensic (for biometric identification and drugs consumption evaluation) and anti-doping analysis. NALDI target is a tool for LFP imaging by using TOF/TOF-MS analysis and microscopic equipment for creation of high-resolution optical images of the fingerprint, and immediately sent to the crime lab for rapid visual and computer-aided analysis [106]. In addition, the advantage of this target application in forensics for identifying drug consumption suspects and anti-doping analysis is confidence of the identity of the sample, as the fingerprint is unique for each person as also physical information is obtained by touching the surface with a finger.…”

“…Previously, various metal oxide nanoparticles (ZnO, Fe 2 O 3 , CeO 2 , TiO 2 ) were synthesized and dusted directly on fingerprint surfaces spiked with drugs traces and without them, using a brush for detection of LMW drugs. Nanoparticles of zinc oxide were synthesized by microemulsions approach, however Fe 2 O 3 nanoparticle application led to the best ionization performance [106].…”