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The production, characterisation, and use of CoPr (x) Cr (2-x) O 4 (x = 0.00, 0.01, 0.03, and 0.05) nanoparticles for improved latent fingerprint (LFP) detection are investigated in this study. CoCr 2 O 4 containing different amounts of Praseodymium(Pr3+) were prepared by solution combustion process using 1:1 M ratio of oxidizer and fuel. X-ray diffraction (XRD) was used to examine the structural characteristics of these nanoparticles, and the results showed that the crystallite sizes and lattice parameters varied while the spinel structure remained constant. The effective synthesis of the intended nanoparticles was indicated by the confirmation of CoCr 2 O 4 presence in the spinel structure by Fourier Transform Infrared Spectroscopy, or FTIR. In particular, the study showed how these nanoparticles can be used in forensic science to identify LFP on a variety of surfaces, including steel, paper, and OHP sheets. In daylight, the CoPr 0.03 Cr 1.97 O 4 (CoPr-3)variation with x = 0.05 performed better, allowing for a clear viewing of Level I–III fingerprint features. 3D interactive plots and high-resolution images demonstrated that the nanoparticles stuck to fingerprint remnants, improving visibility and detail. The study also looked at how stable these nanoparticles were under UV irradiation and aging, and it discovered that CoPr-3 phosphor was remarkably resistant to UV degradation and retained its efficacy for 60 days. These results demonstrate the potential of CoPr (x) Cr (2-x) O 4 nanoparticles as a reliable and effective material for forensic fingerprint analysis, providing notable enhancements in LFP detection sensitivity and resolution. [ABSTRACT FROM AUTHOR]

In this study, the production of an eco-friendly curcumin based nanocomposite fingerprint labeling powder is reported for the first time. This powder was prepared from thermal power plant waste known as coal fly ash. 3-aminopropyltrimethoxysilane (APTMS) was covalently interacted with coal fly ash (CFA/APTMS) and curcumin (CUR) was encapsulated onto CFA/APTMS to give a novel and eco-friendly CFA/APTMS/CUR nanocomposite for LFPs detection with the powder dusting method. Several instrumental techniques including Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), UV–visible spectroscopy, fluorescence spectroscopy (FL), scanning electron microscopy (SEM), energy-dispersive X-ray spectrometry (EDS), and transmission electron microscopy (TEM) were used to characterize this nanocomposite. The CFA/APTMS/CUR nanocomposite was applied as a forensic powder for the development of latent fingerprint (LFPs) images on various porous and non-porous substrates. Level 2 (island, origination, bifurcation, termination, fork, dot, and bridge) and Level 3 (sweat pores and shape of triangles, round, and irregular) were the features of the LFP images. Under visible light conditions, the aging LFPs images were clearly detected on an aluminum foil surface using the nanocomposite powder, which had good sensitivity and minimal background interference. Additionally, LFPs images were developed using CFA/APTMS/CUR nanocomposite on leather substrates for belts and shoes in order to confirm the benefits of the nanocomposite's high sensitivity. This nanocomposite improved LFPs images with unique patterns and showed excellent performance on a variety of surfaces for the development of LFPs. These findings therefore proved that the powdered CFA/APTMS/CUR nanocomposite can be effectively utilized for the development of LFPs images at important crime scenes and for the biometric identification of criminal suspects through fingerprint comparison.

The present work elucidates the fabrication of Barium Lanthanum Oxide nanosheets (BaLa2O4 NSs) via a simple one-pot precipitation method. The acquired results show an orthorhombic crystal system with an average crystallite size of 27 nm. The morphological studies revealed irregular-shaped sheets stacked together in a layered structure, with the confirmation of the precursor elements. The diffused reflectance studies revealed a strong absorption between 200 nm and 350 nm, from which the band-gap energy was evaluated to be 4.03 eV. Furthermore, the fluorescence spectrum was recorded for the prepared samples; the excitation spectrum shows a strong peak at 397 nm, attributed to the 4F7/2→4G11/2 transition, while the emission shows two prominent peaks at 420 nm (4G7/2→4F7/2) and 440 nm (4G5/2→4F7/2). The acquired emission results were utilized to confirm the color emission using a chromaticity plot, which found the coordinates to be at (0.1529 0.1040), and the calculated temperature was 3171 K. The as-prepared nanosheets were utilized in detecting latent fingerprints (LFPs) on various non-porous surfaces. The powder-dusting method was used to develop latent fingerprints on various non-porous surfaces, which resulted in detecting all the three ridge patterns. Furthermore, the as-synthesized nanosheets were used to degrade methyl red (MR) dye, the results of which show more than 60% degradation at the 70th minute. It was also found that there was no further degradation after 70 min. All the acquired results suggest the clear potential of the prepared BaLa2O4 NSs for use in advanced forensic and photocatalytic applications. [ABSTRACT FROM AUTHOR]

This work provides a novel approach to prepare nitrogen-doped carbon nanoparticles (CNPs) coated on a cerium oxide nanorods nanocomposite (N-CNPs/CeO2NRsnC) for the uptake of cadmium (Cd2+) ions and re-using the spent adsorbent, Cd2+-CNPs/CeO2NRsnC for latent fingerprint detection (LFP). N-CNPs were prepared by a thermal method with urea and cabbage powder as precursors. N-CNPs/CeO2NRsnC was developed with N-CNPs and CeO2NRs with a hydrothermal method and characterized by various instrument methods like UV-visible, FT-IR, XRD, BET, XPS, SEM, and TEM. The N-CNPs/CeO2NRsnC had a greater surface area (9.96 m2/g) than N-CNPs (0.64 m2/g). The synthesized N-CNPs/CeO2NRsnC proved to be a good sorbent material to remove Cd2+ from water at a maximum pH 8 and dosage 10 mg/L. The adsorption was spontaneous and endothermic at 25 ºC. In addition, Cd2+-N-CNPs/CeO2NRsnC has been shown to be sensitive and selective for LFP identification on several porous substrates. It is therefore a good labeling agent for latent fingerprint identification in forensic science.

This review paper focuses on the application of forensic science in latent fingerprint detection by the usage of distinct nanomaterials and their benefits with respect to the quality of fingerprint images. The advantages and important results of studies conducted on latent fingerprint detection with various nanomaterials which include metal nanoparticles, metallic oxide nanoparticles, semiconductor quantum dots, carbon dots, polymer dots, fluorescent silica nanoparticles, fluorescent mesoporous silica nanoparticles, fluorescent silica nanoparticles, conjugated-polyelectrolyte dots, aggregation–induced emission luminogens molecule incorporated nanomaterials and uncommon earth fluorescence nanoparticles are critically discussed. Some of the nanomaterials employed for latent fingerprint detection did not result in good quality fingerprint images and these disadvantages are highlighted. More studies are therefore needed to improve the latent fingerprint detection abilities of nanomaterials.

A europium salt-Na[Eu(5,5′-DMBP)(phen)3]·Cl3 (Eu(III)-CPLx) was prepared by using various precursors such as 5,5′-Dimethyl-2,2′-bipyridyl (5,5′-DMBP), 1,10-phenanthroline (phen) and europium chloride hexahydrate (EuCl3·6H2O) by a complexation method. The red emission fluorescent Na[Eu(5,5′-DMBP)(phen)3]·Cl3/D-Dextrose (Eu(III)-CPLx/D-Dex) composite was synthesized by using an adsorption method with Eu(III)-CPLx and D-Dextrose (D-Dex). The Eu(III)-CPLx and fluorescent (Eu(III)-CPLx/D-Dex) composites were characterized by numerous techniques. The fluorescent (Eu(III)-CPLx/D-Dex) composite demonstrated a strong red emission and controlled fluorescence quenching in the solid state and was consequently used in latent fingerprint (LFP) detection. The LFPs were developed by using a powder dusting method (PDM) with Eu(III)-CPLx and fluorescent Eu(III)-CPLx/D-Dex composites on different substrates under daylight and UV-light irradiation at 365 nm. The fluorescent Eu(III)-CPLx/D-Dex composite was effectively explored for developing LFP images on various substrates and also acts as a better labeling agent for LFP detection in forensic science crime scene investigations.

Summary: Exploring organic reactions to construct novel molecules with aggregation-induced emission (AIE) features is an essential branch of AIE research. The fast-paced application of AIE materials in various disciplines, including photoelectricity, molecular biology, medicine, and materials science, has led to an ever-growing need for new AIE molecules. Unlike the synthesis of most “earlier generations” of AIE fluorogens (AIEgens) that require tedious and harsh reactions, chemists now shift their synthetic focus to a selection of reliable and straightforward reactions. The Diels-Alder reaction has been overlooked in this field. Herein, we report a catalyst-free Diels-Alder reaction between 1,3-diphenylisobenzofuran and a series of electron-deficient alkynes to create AIEgens. Photophysical properties of our synthesized 1,3,4-triphenyl-1,4-dihydro-1,4-epoxynaphthalene (ENAP) derivatives are studied systematically, manifesting their AIE characteristics and structure-fluorescence property relationships. Finally, we highlight the diverse applications of some selected ENAP derivatives in latent fingerprint detection, cell imaging, and bacterial staining.

The synthesis of eco-friendly carbon quantum dots (PCQDs) from Pistachio shells is a straightforward process with versatile applications. These PCQDs, derived from non-toxic sources, are generated through a hydrothermal method and have garnered significant attention due to their outstanding properties. While there are many advanced CQDs available, the full potential of PCQDs remains untapped. These PCQDs, with their exceptional optical characteristics, serve as highly sensitive nano-probes for fluorometrically measuring Cu2+ ions. The fluorescence (FL) intensity of these nano-probes shows a linear correlation with Cu2+ ion concentration in the range of 0–4 µM, boasting a low detection limit of around 0.351 µM. This sensitivity is achieved through resonance energy and electron transfer-induced FL quenching. Importantly, carbon dots from Pistachio shells can be used as ink-free patterned substrates, making them ideal for printing and non-destructive collection and detection of latent fingerprints (LFPs). The LFPs can be developed using a simple powder dusting method with PCQDs and are visible under 365 nm UV light. This technique allows for lifting and identifying long-term exposed LFPs from various surfaces without causing any damage. Additionally, extensive research has been conducted on various pore properties such as size, shape, number, position, type, and inter-distance. Mathematical modelling implemented in Python -based software was used to investigate single fingerprints and two overlapped fingerprints. Furthermore, a transparent anti-counterfeiting (AC) film is fabricated using PCQDs and polyvinyl alcohol (PVA), offering effective AC capabilities through their green emission under 365 nm UV light. Notably, these PCQDs exhibit sustainability, exceptional flexibility, and foldability, expanding their potential applications in flexible display devices, dermatoglyphics and data encryption. The overall results clearly demonstrate that PCQDs are a highly efficient luminescent platform with a wide range of applications. [Display omitted] • Hydrothermal method is employed for fabricating PCQDs using Pistachio shell. • The fluorescence quenching of PCQDs due to the resonance energy/electron transfer mechanism enabled highly selective and sensitive measurement of Cu2+ ions. • Developing LFPs using PCQDs via powder dusting method for personal identification. • The outstanding overall performance of PVA@PCQDs composites are highly useful for flat panel displays, LFPs and anti-counterfeiting [ABSTRACT FROM AUTHOR]

A europium salt-Na[Eu(5,5′-DMBP)(phen) 3 ·Cl 3 (Eu(III)-CPLx) was prepared by using various precursors such as 5,5′-Dimethyl-2,2′-bipyridyl (5,5′-DMBP), 1,10-phenanthroline (phen) and europium chloride hexahydrate (EuCl 3 ·6H 2 O) by a complexation method. The red emission fluorescent Na[Eu(5,5′-DMBP)(phen) 3 ·Cl 3 /D-Dextrose (Eu(III)-CPLx/D-Dex) composite was synthesized by using an adsorption method with Eu(III)-CPLx and D-Dextrose (D-Dex). The Eu(III)-CPLx and fluorescent (Eu(III)-CPLx/D-Dex) composites were characterized by numerous techniques. The fluorescent (Eu(III)-CPLx/D-Dex) composite demonstrated a strong red emission and controlled fluorescence quenching in the solid state and was consequently used in latent fingerprint (LFP) detection. The LFPs were developed by using a powder dusting method (PDM) with Eu(III)-CPLx and fluorescent Eu(III)-CPLx/D-Dex composites on different substrates under daylight and UV-light irradiation at 365 nm. The fluorescent Eu(III)-CPLx/D-Dex composite was effectively explored for developing LFP images on various substrates and also acts as a better labeling agent for LFP detection in forensic science crime scene investigations. [ABSTRACT FROM AUTHOR]

This study reports the first new approach of using nitrogen functionalized carbon dots coated on zinc oxide nanoparticles (N-CDs/ZnONPs) as a novel nanocomposite for latent fingerprint detection using the powder brushing method. N-CDs/ZnONPs nanocomposite was prepared using melamine, potato peel waste and zinc acetate dehydrate as precursors. This nanocomposite was characterized by Fourier-transform infrared spectroscopy, UV–Visible spectroscopy, Fluorescence spectroscopy, X-ray diffraction, Raman spectroscopy, Zeta nanosizer, Scanning Electron Microscope, Energy-Dispersive X-ray Spectrometry and Transmission Electron Microscopy. The size of N-CDs was around at 50–20 nm and ZnONPs was around at 40–50 nm. The quantum yield of N-CDs increased the fluorescence intensity of the fluorophore by 5.54%. The N-CDs were coated on surface of ZnONPs to increase the quantum yield and increase the blue emission after formation of N-CDs/ZnONPs by 5.12%. The N-CDs/ZnONPs nanocomposite demonstrated extraordinary sensitivity and selectivity for Latent Fingerprint (LPF) detection on the distinctive non-porous substrates which included aluminum foil, aluminum sheets, an aluminum rod, an iron disc, a compact disc, a black mat, white marble and magazine paper. This nanocomposite acts as a labeling agent and it helped to detect LFP with clear readability ridges and high contrast fingerprint images under UV light irradiation. N-CDs/ZnONPs nanocomposite additionally demonstrated superior ability to reveal readability ridges and clarity and high contrast LFP images with 415 nm and 450 nm light sources and a yellow filter by using a Living Image Microscope. This nanocomposite exhibited advantages such as improved efficiency, a non-toxic nature, good optical properties and good results in the LFP detection of the freshly applied fingerprints. N-CDs/ZnONPs nanocomposite is, therefore, a good alternative material for detection of latent fingerprints in crime investigations. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Latent fingerprint detection plays a great role in forensic science, and considerable efforts have been made on developing efficient and simple strategy to realize clear visualization of latent fingerprints. Among them, fluorescent nanoparticles have attracted increasing interests due to their easy fabrication, good photostability, and low toxicity, but insufficient affinity toward fingerprints has limited their further application. Herein, we report a red-emissive conjugated oligomer/silica hybrid nanoparticle with enhanced affinity toward fingerprints, showing a promising performance on fluorescent detection on latent fingerprints. The conjugated oligomer is covalently doped into the silica nanoparticles, which effectively guarantee its fluorescent quantum yield and photostability. Moreover, the red emission of these nanoparticles also enables the latent fingerprint detection on substrates with fluorescent background, such as plastic and various papers. Most importantly, the introduction of epoxy groups on the silica surface largely enhances its affinity toward fingerprints, compared to that with hydroxy or amino groups, which possibly can be ascribed to its electrostatic attraction and hydrophobic interaction with amino acids and sebaceous substances of fingerprints, respectively. [ABSTRACT FROM AUTHOR]

Porous graphitic carbon nitride (pg-C3N4) was synthesized from bulk g-C3N4 (Bg-C3N4). First, bulk g-C3N4 was prepared by a thermal method with poly-condensation of melamine as a precursor. The pg-C3N4 was synthesized from Bg-C3N4 under ultrasonic treatment in a sulphuric acid medium. Thereafter, pg-C3N4 was combined with commercial silica gel (Slg) to give a fluorescent Slg/pg-C3N4 powder. These prepared materials were characterized by means of distinctive instrumental techniques consisting of UV-visible spectroscopy (UV-visible), fluorescence spectroscopy (FL), Fourier transform infrared spectroscopy (FT-IR) X-ray diffraction (XRD), Raman spectroscopy, Brunauer-Emmett-Teller (BET), scanning electron microscope (SEM), transmission electron microscopy (TEM) and live cell microscopy. The fluorescent Slg/pg-C3N4 powder was used as a labeling agent for the development of latent fingerprints (LFP) on different surfaces such as glass slides, aluminum foil, aluminum sheets, aluminum rods, a compact disc (CD), iron discs, coins, a tea cup and spoon. The LFP images were additionally captured through the use of ultraviolet radiation at 365 nm due to the fluorescent nature of the Slg/pg-C3N4 powder. The LFP images have been also investigated using different commercial powders such as ZnSO4, TiO2 and Iodine vapor for comparison with fluorescent Slg/pg-C3N4 powder. The Slg/pg-C3N4 powder was used to investigate the LFP images submerged in fresh water. Ultimately, the different fluorescent backgrounds of LFP images had been demonstrated using live cell microscopy with pg-C3N4 and Bg-C3N4. The fluorescent Slg/pg-C3N4 powder exhibited potential as a good labeling agent with excessive sensitivity, rapid detection and an eco-friendly nature. This fluorescent Slg/pg-C3N4 powder was also used to develop the LFP images under conditions that are likely to simulate real crime scenes to establish whether this material can be used in real forensic investigations. [ABSTRACT FROM AUTHOR]

The aggregation-induced quenching effect and poor thermal stability issues of carbon dots (CDs) limit their further development in the solid-state lighting and display field. In this work, a red carbon dot/boron nitride nanosheet (rCDs/BNNS) composite was synthesized using boron nitride as a carrier by in-situ embedding of rCDs. Thanks to the uniform dispersion of rCDs and the restraint of BNNS, the prepared rCDs/BNNS composite has excellent fluorescence stability and thermal stability. rCDs/BNNS composites as fluorescent markers can be used to detect potential fingerprints on various surfaces. Furthermore, rCDs/BNNS were dispersed into polyvinyl alcohol (PVA) polymers to prepare rCDs/BNNS/PVA flexible luminescent films. In addition to the excellent stability inherited from rCDs/BNNS, the thin film also exhibits high heat dissipation by reason of the establishment of a heat transfer channel in the PVA by rCDs/BNNS. Moreover, thin films can still maintain original fluorescence after undergoing hundreds or thousands of bends, while possessing sufficient tensile strength. This study provides a facile pathway for the preparation of highly stable CDs luminescent materials, and has a promising application in the forensic identification and flexible luminescent devices' thermal management fields. • A novel rCDs/BNNS composite was synthesized with excellent fluorescence stability and thermal stability. • The rCDs/BNNS/PVA film was obtained by encapsulating rCDs/BNNS into PVA. • Fluorescent film has good luminescence stability and mechanical flexibility. • The film displays outstanding heat dissipation in the application of LED lamp. [ABSTRACT FROM AUTHOR]

[Display omitted] The development of novel imaging agents for fluorescence detection of latent fingerprint is still important for criminal investigation and identity recognition. Herein, we reported a simple and robust method to prepare multi-color conjugated polymer micelles for visualization of fingerprints. A conjugated polyelectrolyte, poly[(9,9-bis(3′-((N,N -dimethyl)-N-ethylammonium)-propyl)-2,7-fluorene)-alt-2,7-(9,9-dioctylfluorene)] (PFN), was dissolved in water forming polymer micelles with blue emission. Green and red emissions were facilely achieved by incorporating small organic fluorophores including coumarin 6 (C6) and Nile red (NR) into the PFN micelles, respectively. These micelles exhibited bright fluorescence both in solution and solid film, where significant aggregation-caused quenching was avoided and fluorescence resonance energy transfer from PFN to C6 or NR was enhanced. Through a simple solution method, these polymer micelles proved their high affinity towards the fingerprint ridges. Accordingly, fluorescent fingerprint images with high-resolution were obtained, which were less interfered by fluorescence background from substrate and overlap between adjacent fingerprints. [ABSTRACT FROM AUTHOR]

Multifunctional solid-state luminescent materials are strongly desired in a wide variety of applications. In this work, green emissive carbon dots@montmorillonite (g-CDs@MMT) composites were synthesized based on green emissive carbon dots and MMT clays in a convenient method by embedding g-CDs into the MMT clays. Due to the confinement of g-CDs in the layered structure of the MMT clay matrix, g-CDs are uniformly dispersed in the resulting g-CDs@MMT solid-state composites. This efficiently prevents the aggregation-induced solid-state luminescence quenching of g-CDs, and a photoluminescence quantum yield of 11% could be achieved by the g-CDs@MMT composites under a 405 nm light. Additionally, the g-CDs@MMT composites exhibit low-toxicity, excellent thermal stability, photostability, resistance to organic solvents, and a small particle size. All of these advantages enable applications in fabricating white light-emitting diodes with different color temperatures, where the g-CDs@MMT composites are applied as the color conversion layer. Furthermore, by using the g-CDs@MMT composites as a fluorescence labeling marker, the latent fingerprint detection on a variety of object surfaces could be realized., (Copyright © 2019 Elsevier Inc. All rights reserved.)