Europium decorated magnetic nanoparticles design for identification of latent fingerprints on different surfaces applications

Matos I.M.; Huaracha S.A.; Félix L.L.; Salazar D.P.; Huaman R.C.; Yacono Llanos J.C. · Results in Physics (2025) · DOI: 10.1016/j.rinp.2025.108426

Resumen

The use of multifunctional nanomaterials with magnetic and luminescent properties has gained significant attention in forensic applications for latent fingerprint identification. In this study, we present a synthesis route for preparing chitosan-coated magnetite nanoparticles (MN-CH) by the coprecipitation method and functionalized with europium ions (MN-CH-Eu). These luminescent magnetic nanoparticles hold potential for the identification of latent fingerprints on different surfaces, including metal, plastic, and glass. Remarkably, structural analysis of MN-CH-Eu confirmed the retention of the magnetite crystalline structure through X-ray diffraction. Scanning electron microscopy and EDS mapping provided evidence of europium presence and its homogeneous distribution on the MN-CH surface. The interactions between chitosan and the nanoparticle core were mainly via electrostatic and hydrogen bonding, as confirmed by Fourier-transform infrared spectroscopy. Importantly, the europium-functionalized nanoparticles exhibited characteristic red photoluminescence, dominated by the hypersensitive 5D0 → 7F2 transition (∼612 nm), when excited under UV light. This emission was preserved due to the spatial isolation of Eu3+ within the chitosan matrix, which minimized quenching effects from the Fe3O4 core. After 24 h at room temperature, developed fingerprints appeared brown under natural light and bright green or reddish under UV illumination, depending on the excitation wavelength (notably 254 nm and 324 nm). The MN-CH-Eu nanoparticles were particularly effective on metal surfaces under both lighting conditions. These findings highlight the successful integration of luminescent and magnetic functionalities within a single nanomaterial, enhancing latent fingerprint detection through both physical adherence and optical contrast, and broadening the scope for forensic applications across various substrates and environmental conditions.

Instituciones: Universidad Nacional de San Agustín de Arequipa; Universidad de Lima