RESUMEN
Diverse strategies have been developed to visualize latent fingerprints (LFPs) that are undetectable by the naked eye. Among them, fluorescence-based approaches have emerged as an attractive method for enabling high-resolution LFP imaging. However, the use of fluorescent probes for LFP detection remains challenging due to cumbersome processing, low selectivity, and high background interference. Here, we demonstrate highly efficient, sensitive, and background-free LFP detection with dual-color emission arising from manganese (Mn)-doped lead halide perovskite (CsPb(Cl1-yBry)3) nanocrystals (NCs). The resulting bright, fluorescent, solid-state nanopowder (NP) permits the visualization of LFP ridge structures and the resolution of level 1-3 LFP features. The dual-color emission of the Mn-doped perovskite NP provides a simple, robust, and effective route to overcome background interference, thereby increasing the resolution and sensitivity of the LFP detection. The combination of the high quantum efficiency and dual emission of Mn-doped perovskite NP offers great potential for forensic science.
RESUMEN
There is an immense literature on detection of latent fingerprints (LFPs) with fluorescent nanomaterials because fluorescence is one of the most sensitive detection methods. Although many fluorescent probes have been developed for latent fingerprint detection, many challenges remain, including the low selectivity, complicated processing, high background, and toxicity of nanoparticles used to visualize LFPs. In this study, we demonstrate biocompatible, efficient, and low background LFP detection with poly(vinylpyrrolidone) (PVP) coated fluorescent nanodiamonds (FNDs). PVP-coated FND (FND@PVP) is biocompatible at the cellular level. They neither inhibit cellar proliferation nor induce cell death via apoptosis or other cell killing pathways. Moreover, they do not elicit an immune response in cells. PVP coating enhances the physical adhesion of FND to diverse substrates and in particular results in efficient binding of FND@PVP to fingerprint ridges due to the intrinsic amphiphilicity of PVP. Clear, well-defined ridge structures with first, second, and third-level of LFP details are revealed within minutes by FND@PVP. The combination of this binding specificity and the remarkable optical properties of FND@PVP permits the detection of LPFs with high contrast, efficiency, selectivity, sensitivity, and reduced background interference. Our results demonstrate that background-free imaging via multicolor emission and dual-modal imaging of FND@PVP nanoparticles have great potential for high-resolution imaging of LFPs.
RESUMEN
In forensic science, developing latent fingermarks using powders is a critical, general method to identify individuals. Photoluminescent Eu(Phen)2 complex intercalated clay hybrids have been used to improve the visualization of fingermarks on nonporous (glass and polymer film) and semiporous (euro and dollar banknotes) substrates. An ion exchange reaction has been successfully used to intercalate Eu(Phen)2 complex ions into the interlayer spacing of two different Na+ -clays, Na+ -montmorillonite and Na+ -hectorite, with different primary particle sizes. To change the surface properties of the obtained hybrid to be more lipophilic, the hydroxyl groups at the edge of the hectorite hybrid were modified with hexadecyltrimethoxysilane via silylation. We investigated the correlation of the size and surface properties of the hybrids with their adhesion to fingermark residues. Fingermarks were successfully visualized using hybrids under UV illumination. In particular, ridge details on semiporous substrates can be more clearly seen using hybrids with smaller primary particles and greater lipophilicity.
RESUMEN
Fluorescent silica nanoparticles (FSNPs) are synthesized through the Stöber method by incorporating silane-modified organic dye molecules. The modified fluorescent organic dye molecule is able to be prepared by allylation and hydrosilylation reactions. The optical properties of as-prepared FSNPs are shown the similar optical properties of PR254A (allylated Pigment Red 254) and have outstanding photostability. The polyvinylpyrrolidone (PVP) is introduced onto the surface of FSNP to enhance the binding affinity of PVP-coated FSNP for latent fingerprints (LFPs) detection. The simple preparation and easy control of surface properties of FSNPs show potential as a fluorescent labeling material for enhanced latent fingerprint detection on hydrophilic and hydrophobic substrates in forensic science for individual identification.
RESUMEN
In many court cases, surveillance videos are used as significant court evidence. As these surveillance videos can easily be forged, it may cause serious social issues, such as convicting an innocent person. Nevertheless, there is little research being done on forgery of surveillance videos. This paper proposes a forensic technique to detect forgeries of surveillance video based on sensor pattern noise (SPN). We exploit the scaling invariance of the minimum average correlation energy Mellin radial harmonic (MACE-MRH) correlation filter to reliably unveil traces of upscaling in videos. By excluding the high-frequency components of the investigated video and adaptively choosing the size of the local search window, the proposed method effectively localizes partially manipulated regions. Empirical evidence from a large database of test videos, including RGB (Red, Green, Blue)/infrared video, dynamic-/static-scene video and compressed video, indicates the superior performance of the proposed method.
