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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.

Fingermarks constitute one of the most important physical evidence categories in forensic science. Improvements on detection and visualization of fingermarks are thus of utmost importance and rely strongly on the developer's properties. Magnetic-fluorescent dual powders are a great alternative, as they can be easily manipulated through a magnetic applicator and, in addition, provide a fluorescent image of the fingermark, improving fingermark/substrate contrast. This work presents a novel dual-fingermark developer powder composed by core–shell iron oxide/silica nanoparticles functionalized covalently with a 2-(5′-amino-2′-hydroxyphenyl)benzoxazole fluorescent dye. The brush and revealing performance of eccrine, natural, and sebaceous deposits fingermarks were evaluated using the powder method on glass substrates with bright and dark surfaces. The nanoparticles displayed superparamagnetic behavior and high emission in the green region. The dual powder adheres into latent fingermarks and produces better visualization of sebaceous residues. The fingermark images under natural light exhibited development with sufficient contrast for dark surfaces. Under UV light, the intense green fluorescence produces better fingermark visualization. Expanded images allowed clear identification of small features, including minutiae. This class of composite nanomaterial showed thus adequate characteristics to be used as a developer for latent fingermarks. [ABSTRACT FROM AUTHOR]

This study presents the synthesis of orange–red emitting Sr9Al6O18:Pr3+ nanophosphors (SAO:Pr3+ NPs) through the solution combustion process. Photoluminescence (PL) spectra revealed concentration quenching at 5 mol % with a critical distance of RC = 21.5 Å, indicating that electric multipolar interactions are responsible for the nonradiative energy transfer in the SAO lattice. Dexter's theory confirmed the quadruple–quadruple interaction as the mechanism behind the quenching. The optimized SAO:5Pr3+ NPs exhibited exceptional properties, including high color purity (CP = 94.2%), cost-effectiveness, eco-friendliness, scalability, and photostability. A fluorescence-based technique was developed using powder dusting to apply latent fingerprint (LFP) visualization and preservation. This method demonstrated high sensitivity, contrast, and no background interference, enabling the detection of LFPs over extended periods. Furthermore, lip prints (LPs), known for their sex differences and stability, have been effectively utilized for reliable and efficient forensic investigations. An unclonable invisible security ink was developed to combat counterfeiting, exhibiting high stability against UV light, aging, and physical abrasion. Mathematical models were employed for various fingerprint image processing tasks, including segmentation, normalization, ridge orientation estimation, ridge frequency estimation, Gabor filtering, binarization, thinning, and minutiae extraction. These algorithms were implemented by using a Python-based environment, resulting in enhanced fingerprints that displayed level I–II features. These findings underscore the potential applications of SAO:Pr3+ NPs in advanced forensic science and data security. This study offers insights into the synthesis, characterization, and application of SAO:Pr3+ NPs, highlighting their suitability for advanced forensic investigations, data security, and anticounterfeiting measures. [ABSTRACT FROM AUTHOR]

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.

TPA-ts-2BF 2 with the bisBF 2 fluorophores displayed AIE active and could be used for the LFP detection, but TPA-ts-BF 2 with a BF 2 fluorophore displayed ACQ effect. Both compounds exhibited excellent MFC behavior, and the emission shift value of TPA-ts-2BF 2 (52 nm) after grinding solid powder was larger than that of TPA-ts-BF 2 (46 nm). [Display omitted] • TPA-ts-BF 2 with a BF 2 fluorophore and TPA-ts-2BF 2 with the bisBF 2 fluorophores were synthesized. • TPA-ts-2BF 2 had excellent AIE active, but TPA-ts-BF 2 displayed ACQ effect. • The solid powders of TPA-ts-2BF 2 had a larger emission red-shift value after grinding. • TPA-ts-2BF 2 was applied to latent fingerprint detection due to its prime AIE property. To better understand the relationship between molecular structure of the mono-/bis-BF 2 -core compounds and mechanofluoroboron behaviors, two pyridine-based difluoroboron compounds with triphenylamine group (TPA-ts-BF 2 and TPA-ts-2BF 2) were designed and successfully synthesized, which TPA-ts-BF 2 including a BF 2 fluorophore and TPA-ts-2BF 2 containing the bisBF 2 fluorophores. Based on the photophysical properties measurements results, it was found that TPA-ts-2BF 2 had more excellent intramolecular charge transfer characteristics than that of TPA-ts-BF 2 , and exhibited significant aggregation-induced emission activity, however, TPA-ts-BF 2 displayed typical aggregation-caused quenching phenomenon. Meanwhile, the emission spectrum of the solid powders of TPA-ts-2BF 2 was red-shifted 52 nm after grinding, that of TPA-ts-BF 2 was red-shifted 46 nm, which was resulted from crystalline state switching to amorphous state. According to the theoretical calculations, we conjectured that TPA-ts-BF 2 with uncoordinated amide linkage moiety had a tendency to forming a more twisted conformance and higher molecular polarity, which made that mechanofluorochromic behavior was worse than that of TPA-ts-2BF 2. Additionally, TPA-ts-2BF 2 was applied to latent fingerprint detection due to its prime aggregation-induced emission property. [ABSTRACT FROM AUTHOR]

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]

Employing grains (wheat, corn, sorghum and rice) as precursors, a series of carbon nanodots (CDs) have been prepared via one‐step hydrothermal treatment. All the CDs have narrow size distribution, roughly spherical shape and similar optical properties. The size depends on the precursors, which varies from 2 to 25 nm. The CDs without further treatment can overcome aggregation‐induced quenching effect, and emit stable bright blue luminescence under UV light irradiation in both colloidal and solid states. Additionally, the mechanism for the solid‐state fluorescence of CDs was also explored. Moreover, the feasibility of CDs as fluorescent labels for latent fingerprint detection was investigated and the results demonstrate well‐defined papillary ridges with higher sensitivity and wider applicability. The work provides a simple, low‐cost, and promising alternative for latent fingerprint detection in forensic science. [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]

Nile red has been an alternative reagent for detecting latent fingerprints on wetted substrates. However, the presence of methanol in nile red solution could make injury to handlers and destroy the traces on surfaces, such as texts on thermal papers. A novel small particle reagent formulation constituting of mesoporous silica nanoparticles (MSNs) based on nile red was prepared to overcome the problem. Compared with the conventional reagents Oil Red O or nile red solution, the nile red‐loaded MSNs are highly selective to lipid residues of fingerprints and showed a greater ability to develop clear, sharp, and detailed fingerprints on thermal papers after these were immersed in water. In addition, it can retain texts on the thermal papers well and use only water as a solvent. These suggested that nile red‐loaded MSNs are a safe, efficient, and convenient method to develop latent fingerprints on wide range of substrates of forensic importance. [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]

Abstract Photoluminescent carbon-based nanomaterials (CNMs) have attracted much attention over the past decade due to their unique optical characteristics and negligible toxicity. However, it is very difficult to obtain red emission of CNMs. Bright red fluorescent carbonized polymer dots (CPDs) were prepared by facilely adjusting the reaction temperature through a one-step solvothermal route, using p -phenylenediamine (PPD) as precursor. The as-synthesized CPDs exhibit excitation-independent emission at about 608 nm under excitation from 365 to 550 nm. Loading CPDs in starch to form CPDs–starch powder, the resultant powder exhibits strong red emission and the typical aggregation-induced fluorescence quenching was effectively suppressed, thus allowing the CPDs to be used in solid state form. More importantly, latent fingerprints (LFPs) on surfaces of various substrates, including glass, stainless steel, marble, adhesive tape, aluminum foil, painted wood, compact disc (CD), and coin, are developed by CPDs–starch powder and exhibit clear patterns and satisfactory ridge details under a 365 nm UV lamp. Furthermore, fingerprints on surfaces with multicolored background and strong florescent properties could also be clearly observed. These results suggest that CPDs–starch powder can be used as a fluorescent labeling agent for the visualization of LFPs in forensic science. Highlights • Red emissive carbonized polymer dots (CPDs) were prepared by one-step solvothermal method. • Loading CPDs in starch to form CPDs–starch powder, which emits strong fluorescence in solid state. • The CPDs–starch power was applied in imaging of latent fingerprint. [ABSTRACT FROM AUTHOR]

Designing nanomaterials with controlled size and shape for desired functions and devices is becoming a prerequisite for current researchers. Nanomaterials also have a significant impact on forensic sciences for the visualization of latent fingerprint. In this context, we report the synthesis of nanostructured barium orthovanadate (Ba 3 V 2 O 8 ) rare-earth free materials via a novel wet-chemical method. The growth of cocoon-shaped nanoparticles is explained by the variation of ethylene glycol and ethylenediaminetetraacetic acid concentrations. In addition, the luminescence properties of the self-luminescent materials are of high quality under ultraviolet light illumination and are useful for the detection of latent fingerprints. The latent fingerprints and their Galton details were clearly observed on different hydrophilic and hydrophobic substrates. The preceding results suggest that the cocoon-shaped Ba 3 V 2 O 8 rare-earth free nanomaterials can serve as a significant candidate for the detection and individualization of latent fingerprints. [ABSTRACT FROM AUTHOR]

Abstract: Fingerprint fluorescence imaging has become one of the most prominent technologies in the field of forensic medicine, but it seldom considers the security protection of detection information, which is of great importance in modern society. Herein we demonstrate that luminescent TbIII–carboxymethyl cellulose (CMC) complex binding aptamer hydrogels that are reversibly responsive to ClO−/SCN− can be used for the selective detection, protection, and storage of fingerprint information. The imaging information of the fingerprint can be quenched and recovered by ClO−/SCN− regulation, respectively, resulting in reversible on/off conversion of the luminescence signals for the encryption and decryption of multiple levels of information. The present study opens new avenues for multilevel imaging, data recording, and security protection of fingerprint information with tunable fluorescent hydrogels. [ABSTRACT FROM AUTHOR]

[Display omitted] • flexible PVA-PVP (50:50) thin films entrapped with 2, 5, and 8 wt% of Fe doped ZnO nanofillers with Vitamin C as a bio-safe coupling agent. • The bactericidal stuff and inhibition zone enhanced with the addition of the ZnO:Fe@Vitamin C nanopowders. • The modified ZFVC NPs greatly enhance the visualization of LFPs regardless of background hindrance and thus can be a promising candidate for LFP detection. In order obtain exceptional composite material, the two polymers, poly(vinyl alcohol) (PVA) and poly(N-vinyl-2-pyrrolidone) (PVP) blend was prepared. First time, vitamin C (Vit C), a biosafe coupling agent was used to modify the surface of ZnO:Fe nanoparticles (NPs)NPs. To the polymer blend, surface modified ZnO:Fe of different ratios (2, 5 and 8 wt%) NPs were used as a matrix filler. Reported method of preparation effectively disperse the NPs quickly in to the polymer matrix and it was an eco-friendly approach. The obtained nanocomposites (NCs) were characterised by advanced experimental techniques. Examining the structure of the molecules revealed the morphology of the NCs and the compatibility of the NPs with the blended polymer. TGA results confirms the improved thermal characteristics for the NPs doped samples than the pure polymer blend. The optical absorbance of the produced NCs was also affected by embedding the modified NPs in the blend polymer. The hydrophilicity decreased for various ratios of the modified NPs loaded in the blend polymer, according to the contact angle measurements. Use of PVA-PVP-ZnO:Fe@Vitamin C (5 wt%) NCs were demonstrated for their potentiality in the food preservation, The self-life of grapes was qualitatively enhanced and utility in food wrapping applications has been demonstrated. With the addition of the ZnO:Fe@Vitamin C nanopowders (ZFVC), it acts as the bactericidal substance and inhibition zone improved. The modified ZFVC NPs significantly improve LFP visualisation despite background interference, making them a suitable candidate for LFP identification. [ABSTRACT FROM AUTHOR]

An orange-emitting cationic iridium (III) complex [(PPPA) 2 Ir(Phen)]PF 6 (PPPA: N,N-diphenyl-4'-(pyridin-2-yl)-[1,1′-biphenyl]-4-amine, Phen: 1,10-phenanthroline) was synthesized and characterized. [(PPPA) 2 Ir(Phen)]PF 6 shows high aggregation-induced emission (AIE) activity mainly based on restrained intramolecular rotation (RIR) of the triphenylamine group in its main ligands. When it is dissolved in CH 3 CN–H 2 O mixtures (5.0 × 10−5 mol L−1) with water fractions (f w) from 0% to 90% (in vol %), only the solutions with f w ≥ 60% can emit bright orange light, the corresponding photoluminescence quantum yields (PLQY) increased from 2.3% (at f w = 60%) to 47.8% (at f w = 90%), the PLQY further increased to 52.2% in solid powders. This complex was successfully used for latent fingerprints (LFPs) visualization and detection on both non-porous and porous surfaces via a simple powder dusting method, due to its high AIE activity as well as good adhesion to secretion residues, under 365 nm UV light, the fingerprints developed from whether fresh or aged LFPs all show high brightness and high contrast, the first, second, and third level details of the fingerprints all can be clearly distinguished. The first, second, and third level details of the fingerprints developed by the AIE-active orange-emitting cationic iridium (III) complex all can be clearly distinguished. [Display omitted] • A novel cationic iridium (III) complex shows high AIE activity based on RIR mechanism. • The complex powders emit bright orange light with PLQY up to 52.2%. • LFPs detection on both non-porous and porous surfaces via a powder dusting method. • 1st-, 2nd-, and 3rd-level details of fingerprints all can be clearly distinguished. [ABSTRACT FROM AUTHOR]

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(Cl 1-y Br y ) 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.

In this work the synthesis and structural characterization by NMR and single crystal X-Ray Diffraction of four new phenothiazine-carboxylate salts (lithium, sodium, potassium, and calcium salts respectively) is reported together with a description of their use as contrast agents in the fabrication of new fluorescent electrospun polyvinylpyrrolidone nanomaterials suitable for latent fingerprint (LFP) detection were reported. The optical properties of the new fluorophores and fluorescent electrospun polymer (FEP) nanomaterials (λem = 448–467 nm) were evaluated by UV–Vis absorption/emission spectroscopy. Fluorescence lifetime imaging microscopy (FLIM) analysis indicated an intense and uniform fluorescence in solid state, with fluorescence lifetime increasing significantly for FEP material (8–11 ns) in comparison to the correspondent blank fluorophore. Scanning electron microscopy (SEM) investigations revealed the size of the new FEP materials situated in the nanometric range with fiber or granular morphology. The newly synthesized FEP nanomaterials were successfully tested in the detection of LFP from various smooth or porous surfaces such as glass, metal, plastic, ceramic or wood and demonstrated a versatile capability of direct visualization in UV and daylight of enhanced LFP, as well as of primary lifts collected by gently pressing the polymeric mats on the tested surfaces. The quality of the collected LFPs images was determined mainly by the fluorophore structure, best visualization results being obtained with the phenothiazine sodium carboxylate salt. The new FEP nanomaterials appear suitable for highly accurate forensic investigations, supporting a direct analysis by photography, an expeditive and non-hazardous alternative for avoiding the disadvantages of techniques such as dusting or chemical treatment currently applied in the dactyloscopic identification of a suspect person at the crime scene. [Display omitted] • New blue fluorescent 10-ethyl-10 H -phenothiazine-3-carboxylate salts (PC). • PC structure confirmed by single-crystal X-ray diffraction (XRD). • New fluorescent electrospun polyvinylpyrrolidone with phenothiazine carboxylate. • UV and daylight visualization of latent fingerprints (LFPs). • Accurate LFPs sampling using FEP. [ABSTRACT FROM AUTHOR]

The article focuses on a research on latent fingerprint detection using semiconductor quantum dots (QD) as a fluorescent inorganic nanomaterial for forensic application. It states that limitations on the detection of latent fingerprint found in crime scenes can be overcome by emission of nanoparticles. It mentions that it use of QD as fluorescence labeling markers for latent fingerprint visualization and introduce silica shells on QD surface for adsorption of poly(vinyl pyrrolidione) (PVP).

This paper developed a facile method to synthesize CdTe@SiO 2 /Ag nanocomposites by coupling uniform Ag nanoparticles on core–shell CdTe@SiO 2 quantum dots via simple impregnation of CdTe@SiO 2 functionalized with amino groups in Ag nanoparticle sols. The obtained CdTe@SiO 2 /Ag nanocomposites show efficient fluorescence and effective antibacterial activities. Besides, because of the existence of SiO 2 , the CdTe@SiO 2 /Ag nanocomposites manifest strong adhesive affinity and chemical stability, allowing the long-term preservation of fluorescence and affording affinity with latent fingerprints. Thus, the CdTe@SiO 2 /Ag nanocomposites are explored as alternative fluorescent markers for latent fingerprint detection to provide better resolution, high sensitivity, and antibacterial activities. Meanwhile, the CdTe@SiO 2 /Ag nanocomposites may be used as alternative fluorescent markers for enhanced latent fingerprint detection on a variety of object surfaces in criminal science for individual identification. [ABSTRACT FROM AUTHOR]

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Heavy metals are becoming a huge problem in the environment and lead is one of them. Lead is disposed into water systems from huge industries such as paint industry, mining, and electroplating. In this study, manganese oxide coated fly ash (MnO 2 -CFA) was synthesized and characterized. The BET surface area of CFA MnO 2 -CFA was 18.4196 m2/g, 3 times more than the raw CFA (5.9231 m2/g). Batch adsorption experiments indicated that the uptake of Pb2+ fitted well in a Elovich kinetics model while the adsorption isotherm best fitted the Langmuir model with a maximum adsorption capacity of 141 mg/g at 40 °C and a pH of 7. Thermodynamic parameters obtained proved that the adsorption of Pb2+ ions using the MnO 2 -CFA was endothermic and spontaneous. Furthermore, the adsorbent was highly selective towards Pb2+ in the presence of Mn2+, Zn2, Ni2+and Cd2+. The Pb2+ removal % from a real water sample spiked with 30 mg/L Pb2+ was found to be 83.33%. The spent adsorbent was further applied in latent fingerprint detection which showed that Pb2+-MnO 2 -CFA produced clearer latent finger print (LFP) images compared to MnO 2 -CFA. LFP images were still clear 8 days after application of the spent adsorbent, proving that Pb2+-MnO 2 -CFA is a promising labelling agent. [Display omitted] • Manganese oxide coated fly ash was synthesized by hydrothermal method. • MnO 2 -CFA surface area (18.4196 m2/g) was 3 times more than the raw CFA (5.9231 m2/g). • MnO 2 -CFA shows the maximum adsorption capacity of 60.61 mg g−1 (Pb2+) at 50 °C. • Reuse application of Pb2+-MnO 2 -CFA spent adsorbent for LFP detection under day light condition. [ABSTRACT FROM AUTHOR]

Four new D-π-A type N,O -chelated BF 2 complexes (TCBOB , TCBTB , TCQB and TCPB) were synthesized. It was found that TCPB bearing the ligand of N -(1-pyridinyl)benzoamide shows gelation ability in methylcyclohexane, DCM/peteroleum ether, etc. The time-dependent UV–vis absorption and fluorescent emission spectral changes during the gel formation revealed that π-π interactions play important roles in the self-assembling processes. Particularly, the emission of the xerogel-based film of TCPB can be quenched by TFA (trifluoroacetic acid) vapor, and it showed high performance in the detection of TFA compared with the spin-coating films of TCBOB , TCBTB and TCQB. In addition, the BF 2 complexes exhibited reversible mechanofluorochromic behavior under the treatment of grinding/fuming or heating, and TCPB gave high-contrast mechanofluorochromism compared with others. XRD patterns in different solid states demonstrated that the external mechanical forces can induce the transformation from the crystalline to the amorphous states. Powder of TCPB was also used to image latent fingerprints on surface of glasses, and distinct fluorescent images were obtained. [Display omitted] • New BF 2 complexes were synthesized. • Gelation abilities and MFC properties of them were studied. • They were first used to detect LFP. [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]

In this paper, non-conjugated organosilicone fluorescent nanoparticles (Si-NPs) were synthesized by the Stöber method. The Si-NPs have a diameter of approximately 30 nm, uniform particle size, and a quantum yield of up to 70.6% ultra-bright blue light emission. The prepared non-conjugated siloxane fluorescent small molecule is covalently bonded to the silica matrix. The Si-NPs exhibited excellent stability in ultraviolet irradiation and a wide pH range, and their improved stable optical properties are attributable to the protection of the silica matrix. In addition, the effectiveness of Si-NPs for potential fingerprint detection on a variety of substrates is demonstrated. Clear optical/fluorescent images of the ridges and spaces with high contrast and resolution are obtained because the particle size of the obtained Si-NPs is much smaller than the width of the fingerprint ridges. Image 1 • Si-NPs without typical fluorophores are applied for latent fingerprint imaging. • Si-NPs particles have blue fluorescence with quantum yield being 70.6%. • Si-NPs exhibit excellent stability in ultraviolet irradiation and wide pH range. • Improved stability is attributed to the protection of the silica matrix. • Clear fluorescent images on various substrates with high resolution are obtained. [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.)