Metal oxide nanoparticles for latent fingerprint visualization and analysis of small drug molecules using surface-assisted laser desorption/ionization mass spectrometry
We explored the applicability of different metal oxide nanoparticles (NPs; ZnO, TiO2, Fe2O3, and CeO2) 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 Fe2O3 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.
KeywordsMetal oxide NPs SALDI Latent fingerprints Small molecules Visualization
The authors gratefully acknowledge the support of the Kuwait Foundation for the Advancement of Sciences (KFAS) under project code P115-14SC-04. Special thanks are extended to RSPU Facilities nos. GS 01/01 and GS 02/01, and the Chemistry Department of Kuwait University for implementing the required MALDI-TOF/TOF MS analyses. The Nanoscopy Science Centre is also gratefully acknowledged.
Compliance with Ethical Standards
All procedures performed in studies involving human participants were approved by the Health Sciences Centre Ethical Committee of Kuwait University and were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards.
Informed consent to use their fingerprints was obtained from healthy volunteers and was approved by the Health Sciences Centre Ethical Committee of Kuwait University.
Conflict of interest
I certify that all persons who have made substantial contributions to this manuscript are listed as coauthors, and there is no conflict of interest.
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