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To overcome the drawbacks of traditional techniques for improving latent fingerprint (LFP) and biosensing applications, such as low sensitivity, high background interference, complicated setups, and poor universality, we developed Zn1−xEuxO (x = 0, 0.25, and 0.5) nanoparticles via a co-precipitation method. On diverse porous and non-porous surfaces, LFPs coated with optimized Zn1−xEuxO (x = 0, 0.25, and 0.5) nanoparticles exhibit clearly defined ridge patterns with good sensitivity and little background interference. The Tauc plot determined the band gap energy, which declines with increasing Eu doping and was found to be 3.04, 3 and 2.95 eV for x = 0, 0.25, and 0.5, respectively; the increase in Eu doping levels in the ZnO host lattice resulted in enhanced photoluminescence (PL) capabilities. The photocatalytic activity response was investigated using the organic methylene blue (MB) dye as the pollutant. The photocatalytic activity of the Eu-doped NPs exhibited a higher performance of 94.83% compared with undoped ZnO NPs. Our findings open up new possibilities for utilizing optimized Eu-doped ZnO nanoparticles in forensic research and in the MB dye degradation process. [ABSTRACT FROM AUTHOR]

Organic luminescent materials with time‐dependent emission colors show promising applications in the fields of chemical sensing, high‐resolution bioimaging, and high‐security information encryption. Herein a time‐dependent fluorescence system based on a spirocyclic scaffold‐bridged cyanostilbene dimer (SDCS) as the single component in a mixed CH3CN/H2O solvent is presented. Specifically, the original orange‐emitting nanoparticles prepared from SDCS by reprecipitation can transform into green‐emitting nanosheets over time driven by supramolecular self‐assembly. It is worth noting that such a transformation rate can be controlled by tuning the water fraction. Based on these unique properties, fluorescent binary codes are developed, enabling time‐dependent information encryption with a higher level of security. Moreover, the dual color can be individually fixed by solid matrices such as hydrogel or powder. The obtained luminescent powders are successfully used in two‐color fluorescence imaging of latent fingerprints. This work demonstrates the use of a supramolecular strategy to control multiple emissions in a single‐component system for multifunctional applications. [ABSTRACT FROM AUTHOR]

Organic–inorganic hybrid Ge(II)‐based metal halides have garnered significant interest due to their intriguing photophysical properties and environmentally friendly characteristics. However, challenges such as poor stability, low emission intensity, and a complex synthesis process have hindered their widespread application. In addressing these issues, a breakthrough in the large‐scale production of Sb3+‐doped Ge(IV)‐based metal halide (C13H14N3)2GeCl6 phosphors at room temperature through a straightforward solution method is presented. The synthesized compound exhibits a remarkable bright broad yellow emission band at 590 nm, boasting a photoluminescence quantum efficiency of 99.53 ± 0.06% the highest among Ge(IV)‐based metal halides. Notably, the introduction of Sb3+ induces the formation of Jahn–Teller‐like self‐trapped excitons in [SbCl6]3− species, attributable to lattice distortion and strong electron–phonon coupling. Consequently, Sb3+‐doped (C13H14N3)2GeCl6 demonstrates a large Stokes shift (221 nm) and a prolonged decay lifetime (3.06 μs). Furthermore, the Sb3+‐doped compound exhibits commendable chemical‐ and photostability, prompting exploration in applications such as white light‐emitting diodes and latent fingerprint detection. This work not only provides a practical approach for designing economically viable, environmentally friendly, and highly efficient emission phosphors but also paves the way for novel directions in their expanded application. [ABSTRACT FROM AUTHOR]

Stimuli‐responsive molecules with dynamic covalent bonds show physicochemical changes in response to external stimuli but also exhibit active molecular motions and poor luminescent properties. Hence, the manipulation and balance of dynamic and static behaviors are crucial for the development of multifunctional materials. In this work, a series of hydrazone‐based compounds with aggregation‐induced emission characteristics and hydrogen‐halogen interactions are designed and synthesized. Among them, TPAHPyCl showed the highest quantum yield of 54.0% and morphology‐dependent mechanochromic properties due to the strong chlorine‐hydrogen interactions and other multiple intermolecular interactions in the aggregate state. With the help of the turn‐on emission response to the non‐polar environment of lipid droplets, TPAHPyCl is also utilized for high‐resolution latent fingerprint detection and intracellular lipid‐droplet imaging, demonstrating multiple functions with dynamic and static properties. This work highlights the role of halogen‐hydrogen interactions and provides a new strategy to develop stimuli‐responsive materials with dynamic and static features. [ABSTRACT FROM AUTHOR]

Mass spectrometry imaging (MSI) is increasingly used to produce chemical images of latent fingerprints. Yet, the actual benefits of MSI for real case studies have to be assessed for fingerprints previously processed by forensic techniques. Here, we have evaluated the compatibility of desorption electrospray ionization (DESI) with the fingerprint enhancement technique involving Oil Red O (ORO). Methods: To optimize the ionization step independently from surface extraction, the ORO reagent and its mixture with model compounds (triolein and linoleic acid) were first studied in solution using high-resolution electrospray ionization tandem mass spectrometry (ESI-MS/MS). Then, DESI-MSI experiments were performed in both polarity modes for ORO-processed fingermarks deposited on pieces of paper used as porous substrates. Results: ESI-MS of ORO reveals a complex mixture of azo dyes. Two main impurities detected beside the targeted species were characterized using MS/MS and then were usefully employed to produce DESI-MS images of fingermarks, decreasing the scanning rate to get sufficient ion abundance from natural fingerprints. ORO did not prevent chemical profiling, and one major added value of this pink dye was to produce MS images with contrast that cannot be obtained optically for some colored substrates. Conclusions: DESI-MS has demonstrated imaging compatibility with the application of ORO used to enhance latent fingerprints on paper and could also enable chemical profiling in natural fingermarks. In addition, MS images of ORO impurities were of higher quality than optical ones for fingerprints revealed on colored paper. [ABSTRACT FROM AUTHOR]

Fluorescent carbon dots (CDs) are a new type of photoluminescent nanomaterial. Solid-state CDs usually undergo fluorescence quenching due to direct π-π* interactions and superabundant energy resonance transfer. Therefore, the preparation of solid-state fluorescent CDs is a challenge, especially the preparation of long wavelength solid-state CDs. In this research, long wavelength emission CDs were successfully synthesized by solvothermal methods, and the prepared CDs showed good hydrophobicity. The composite solid-state CDs/PVP (Polyvinyl pyrrolidone) can emit strong red fluorescence, and the quantum yield (QY) of the CDs/PVP powder reaches 18.9%. The prepared CDs/PVP solid-state powder was successfully applied to latent fingerprint detection. The results indicate that the latent fingerprints developed by CDs/PVP powder have a fine definition and high contrast visualization effect, which proves that the prepared CDs/PVP has great application potential in latent fingerprint detection. This study may provide inspiration and ideas for the design of new hydrophobic CDs. [ABSTRACT FROM AUTHOR]

A molten salt-assisted method for the synthesis of Eu 3 + -doped bismuth molybdate (BMO: Eu 3 + ) phosphor was proposed. (BMO: Eu 3 + ) phosphors with different phase structures were obtained by changing the calcination temperature. The applications in LED devices and latent fingerprint recognition of the obtained product were explored. The results of structural characterizations and scanning electron microscope (SEM) photographs analysis prove that the products exhibit different crystal structures and morphologies with the change of calcination temperature. Based on the above findings, the as-prepared products have potential applications in the field of WLED and potential fingerprint recognition. [ABSTRACT FROM AUTHOR]

[Display omitted] • Three zero-dimensional organic metal halides with different emission characteristics were synthesized. • The photophysical properties of the as-synthesized compounds were investigated in detail. • We demonstrated Sb3+-doped compounds in single-component white light illumination latent fingerprint detection. • Based on Sb3+-doped Sn(IV) compounds, a triple-mode reversible PL switch of off-onI-onII-off was achieved under different external stimuli. The host lattice environments of Sb3+ has a great influence on its photophysical properties. Here, we synthesized three zero-dimensional organic metal halides of (TPA) 2 SbCl 5 (1), Sb3+-doped (TPA)SnCl 5 (H 2 O)·2H 2 O (Sb3+-2), and Sb3+-doped (TPA) 2 SnCl 6 (Sb3+-3). Compared with the intense orange emission of 1 , Sb3+-3 has smaller lattice distortion, thus effectively suppressing the exciton transformation from singlet to triplet self-trapped exciton (STE) states, which makes Sb3+-3 has stronger singlet STE emission and further bring a white emission with a photoluminescence quantum efficiency (PLQE) of 93.4%. Conversely, the non-emission can be observed in Sb3+-2 even though it has a similar [SbCl 5 ]2- structure to 1 , which should be due to its indirect bandgap characteristics and the effective non-radiative relaxation caused by H 2 O in the lattice. Interestingly, the non-emission of Sb3+-2 can convert into the bright emission of Sb3+-3 under TPACl DMF solution treatment. Meanwhile, the white emission under 315 nm excitation of Sb3+-3 can change into orange emission upon 365 nm irradiation, and the luminescence can be further quenched by the treatment of HCl. Therefore, a triple-mode reversible luminescence switch of off-onI-onII-off can be achieved. Finally, we demonstrated the applications of Sb3+-doped compounds in single-component white light illumination, latent fingerprint detection, fluorescent anti-counterfeiting, and information encryption. [ABSTRACT FROM AUTHOR]

A novel hydroxy benzothiazole based yellow fluorescent powder (labelled as 2‐SiO2) was prepared by adsorption of 2 on silica (4 % w/w) for visualization of latent fingerprints (LFPs) and glove prints using powder dusting method. The solid‐state spectrum of 2‐SiO2 shows emission peak at 550 nm with CIE‐1931 coordinates (x,y ${x,y}$) of 0.42, 0.50 and yellow colour purity is 58.6 %. The high fluorescence of 2 in the solid‐state could be attributed to AIE+ESIPT features. Due to high fluorescence (ϕ=0.422) ${(\varphi{} =0.422)}$ of 2‐SiO2 (4 % w/w) powder, fluorescence imaging of LFPs on a variety of porous and non‐porous substrates including glove prints, up to levels 1–3, without any post‐treatment has been achieved. The 2‐SiO2 showed strong interaction with D‐Glucose, urea and lactate components present in sweat. The practical applications of 2‐SiO2 powder have been demonstrated by analysis of LFPs, development of LFPs at different temperatures; aged, stained fingerprints and preservation of developed fingerprints for documentation purposes. [ABSTRACT FROM AUTHOR]

Fingerprints are essential for human identification and are valuable tools in criminal investigations. The pursuit of new materials for digital printing is expanding, with increasing interest in natural compounds such as bixin, sourced from annatto seeds. Despite its traditional use as a natural dye with medicinal properties, the potential of bixin in papilloscopy remains largely untapped. In this study, we meticulously extracted bixin from annatto seeds and meticulously developed composites incorporating zinc carbonate (bixin/ZnCO3) and kaolinite (bixin/kaolinite). UV-visible spectroscopy was used for characterization, and the extracted bixin showed absorption peaks at 429, 453, and 481 nm, which were very similar to standard peaks at 429, 457, and 487 nm. The two samples also had the same retention times (7.07 min) according to further liquid chromatography analysis. Sweat pores were easier to detect thanks to the effectiveness of the bixin/ZnCO3 and bixin/kaolinite composites in creating high contrast sebaceous and natural latent fingerprints. These results highlight the composites' potential as novel and fascinating instruments for papilloscopy applications, which might also improve forensic investigations. [ABSTRACT FROM AUTHOR]

The analysis of fingerprint chemical composition is a meaningful way to excavate the multidimensional information of fingerprint, including the donor profiling information and the age of a fingerprint, which broadens the evidential values of fingerprint, especially for the partial and distorted fingerprint. But the research remains still in the pilot phases or is ongoing. Amino acids are the dominant organic substances in latent sweat fingerprint and influenced by many donor factors. Hence, their content reflects personal information of donors. Forensic science will be revolutionized if suspects can be individualized by their amino acid content. The diverse nature, distinct physicochemical properties, and ultra‐micro levels of amino acids present in fingerprints make it hard to detect. A high sensitivity method for detecting and quantifying multiple amino acid components is required. UHPLC‐QqQ MS/MS offers high sensitivity, high separation, simultaneous multicomponents detection, and no derivatization, making it an ideal method for detecting and analyzing amino acids in fingerprints. Therefore, in this study, we propose and validate an efficient UHPLC‐QqQ MS/MS method for the extraction and analysis of 13 amino acids from fingerprint. We compared the results of amino acids of 10 different substrates and found that the inherent amino acids in most porous substrates would have been extracted along with the fingerprint amino acids, making them unsuitable for quantitative amino acid analysis. Instead, plastic sheets are ideal substrates for laboratory studies. Then, extensive experiments were conducted among 30 donors for multidimensional information analysis. The type of samples analyzed were eccrine‐rich fingerprints. A Binary Logistic Regression (BLR) model was developed, and the female and male donors were successfully differentiated by amino acids in fingerprints. Two other mathematical models were also developed to verify the accuracy, and all three different mathematical models were able to identify donors of different genders with over 90% accuracy. This demonstrates that amino acids have the potential to provide more information for donors as metabolic markers. In the future, we will conduct a series of experiments to analyze more multidimensional information for individual identification by amino acid content in the fingerprint. [ABSTRACT FROM AUTHOR]

Latent fingerprints were successfully visualized using fluorescence lifetime imaging (FLIM) on paper which emits strong fluorescence with a lifetime close to that of fingerprints and thus from which it is difficult for time‐resolved spectroscopy to visualize fingerprints. Latent fingerprint samples on paper were excited using a 450 nm or 532 nm nanosecond pulsed‐laser, and time‐resolved fluorescence images were obtained at a delay time of 6–16 ns in intervals of 1 ns, to the excitation pulse. The excitation beam was expanded using a lens, and the fluorescence from the fingerprints was captured using an intensified CCD camera. Because of the large fluorescence intensity of the background paper of approximately two to four orders of magnitude larger than that of the fingerprint, the fingerprint was not visualized on each fluorescence image by time‐resolved spectroscopy. However, the fingerprint was visualized in a FLIM image constructed using a series of the fluorescence images for the case with the fluorescence intensity of the background paper being four orders of magnitude larger than that of the fingerprint. The difference in fluorescence lifetime in the FLIM image of the visualized fingerprint and background paper was in the order of 0.1 ns, which was an order of magnitude smaller than the inherent fluorescence lifetime of a few nanoseconds for the fingerprints and paper. It was demonstrated that, at a background fluorescence intensity with a certain order of magnitude larger than that of fingerprints, FLIM has the potential to visualize latent fingerprints which cannot be visualized by time‐resolved spectroscopy. [ABSTRACT FROM AUTHOR]

Since waste materials are used to identify, individualize, and evaluate evidence like fingerprints, palmprints, footprints, etc. that are found at a crime scene, they have a substantial impact on the field of forensic science. Many waste powders have recently been employed in fingerprint recognition. Nanosheets made up of eggshells have been put forward as an application in friction ridge development. Eggshell is a biochemical substance made up of chemical compounds like calcium carbonate, which is considered as a waste product. For the formation of an eggshell nanosheet (ESN), shells are dried and crushed into a fine powder and to get this powder in the form of a nanosheet, the Ball milling technique is used. The synthesis of pure ESN is confirmed by Scanning Electron Microscopy (SEM) and X‐ray diffraction (XRD) techniques. The size of nanosheets ranged from 30 to 90 nm as shown in SEM images. Developed powder is then used for the application of fingerprint development and it provides excellent results on all porous, non‐porous, and semi‐porous surfaces. Thus, this newly synthesized ESN powder can be used as a significant powder method in latent fingerprint technology. [ABSTRACT FROM AUTHOR]

A novel pyridine-based difluoroboron compound containing a triphenylamine moiety was designed and synthesized. It exhibited intramolecular charge transfer features and aggregation-induced emission enhancement (AIEE) activity, as well as reversible mechanofluorochromic behavior upon grinding–fuming. The photophysical properties in solutions were explained by molecular simulation, and the results of XRD patterns and X-ray single crystal analyses illustrated that the switching of crystalline–amorphous states and the planarization of the molecular conformation in the solid state upon grinding gave rise to mechanofluorochromic behavior. Additionally, under 365 nm UV light, this compound was successfully used for latent fingerprint visualization testing due to its excellent AIEE activity, and inkless writing testing due to its solid-state color with high brightness and contrast upon grinding–fuming. [ABSTRACT FROM AUTHOR]

Fingerprints are unique patterns used as biometric keys because they allow an individual to be unambiguously identified, making their application in the forensic field a common practice. The design of a system that can match the details of different images is still an open problem, especially when applied to large databases or, to real-time applications in forensic scenarios using mobile devices. Fingerprints collected at a crime scene are often manually processed to find those that are relevant to solving the crime. This work proposes an efficient methodology that can be applied in real time to reduce the manual work in crime scene investigations that consumes time and human resources. The proposed methodology includes four steps: (i) image pre-processing using oriented Gabor filters; (ii) the extraction of minutiae using a variant of the Crossing Numbers method which include a novel ROI definition through convex hull and erosion followed by replacing two or more very close minutiae with an average minutiae; (iii) the creation of a model that represents each minutia through the characteristics of a set of polygons including neighboring minutiae; (iv) the individual search of a match for each minutia in different images using metrics on the absolute and relative errors. While in the literature most methodologies look to validate the entire fingerprint model, connecting the minutiae or using minutiae triplets, we validate each minutia individually using n-vertex polygons whose vertices are neighbor minutiae that surround the reference. Our method also reveals robustness against false minutiae since several polygons are used to represent the same minutia, there is a possibility that even if there are false minutia, the true polygon is present and identified; in addition, our method is immune to rotations and translations. The results show that the proposed methodology can be applied in real time in standard hardware implementation, with images of arbitrary orientations. [ABSTRACT FROM AUTHOR]

The development of high‐intensity fluorescent materials is always the focuses and forefront projects because of their important applications in displays, sensing and detection fields. In recent years, the detection of explosives has attracted increasing attention due to security and counterterrorism issues. Herein, two diphenyl−anthracene (DPA) derivatives were designed and synthesized by introducing strong electron withdrawing fluorine atoms and cyano‐groups to DPA, which exhibited strong fluorescence both in the solution and solid phase with the absolute quantum yields up to 70.4 % and 45.9 % respectively. The detection behavior of nitroaromatic explosives such as picric acid (PA), 2,4,6‐trinitrotoluene (TNT) and 3‐Nitropropionic acid (3‐NP) also shows good sensitivity with the quenching constant as high as 6.3×104 L mol−1. Theoretical calculation demonstrates that the fluorescence quenching behavior of the two DPA derivatives is caused by the behavior of photoinduced electron transfer (PET) and the resonance energy transfer (RET) studies explained the higher sensitivity and selectivity of both compounds towards PA than other nitro‐containing explosives. Furthermore, the strong solid‐state fluorescence of the DPA derivatives also shows excellent advantages in enhancing latent fingerprint recognition. [ABSTRACT FROM AUTHOR]

Synthetic-mica materials have shown multifunctional performances due to their distinctive adhesion and cation exchange ability. In this work, a novel Eu3+-doped synthetic-mica named as barium tetrasilicate fluorphlogopite (BaMg 2 Si 4 O 10 F 2) phosphor was prepared by the high-temperature solid state reaction process for the first time. The as-prepared mica samples possess a distinct lamellar structure, as indexed by X-ray diffraction, scanning and transmission electron microscopy means. The photoluminescence results manifest that the phosphor can generate bright red emission at 614 nm corresponding to the characteristic 5D 0 →7F 2 transition of Eu3+ as excited with UV light, and the luminescence intensity is nearly 9-fold in comparison with that in original fluorphlogopite. The more fantastic result is that the emission intensity at 373 K still retains 95 % in respect to that at ambient temperature, demonstrating the phosphor system with excellent optical thermal stability. The optimal BaMg 2 Si 4 O 10 F 2 :8%Eu3+ phosphor powder has been used to discern the latent fingerprints on the surface of diverse non-porous and semi-porous substrates, which reveal the superior visibility as irradiated with 254 nm UV light. The Eu3+-doped BaMg 2 Si 4 O 10 F 2 synthetic-mica is a promising phosphor material for latent fingerprint identification application. [ABSTRACT FROM AUTHOR]

In this article, we present the synthesis and characterization of Eu3+-activated KMLS:Eu3+ phosphor for pc-WLEDs, latent fingerprint detection, and security ink applications. The structural phase, luminescent property, and colour purity of the as-prepared phosphor were investigated. XRD profiles and Rietveld refinement analysis confirm the hexagonal crystal system of the as-prepared phosphor. Concentration quenching effect was not observed up to 17 mol% of Eu3+. The site occupancy preferences of Eu3+ were investigated using the bond-valence model. The CIE-coordinate of optimal Eu3+ is estimated to be close to the standard NTSC value, and color purity is found to be above 90% for all the Eu3+ concentrations. Both Judd-Ofelt (J-O) analysis and asymmetric ratios revealed that the local environment around Eu3+ is asymmetric in nature. The radiative properties, including the stimulated emission cross section and optical gain parameters, of the highest concentration of Eu3+ (17mol%) were determined. Further, the results of thermal quenching analysis show that 91% of the luminescence intensity can be maintained at 150 °C, demonstrating good thermal stability. The multilevel ridge characteristics of the latent fingerprint stained with as-prepared phosphor could be clearly visualized under 254 nm UV excitation. All of the above results indicate that as-prepared phosphor materials can be suitable for use in forensic applications as well as solid state lighting applications. [ABSTRACT FROM AUTHOR]

A highly fluorescent material exhibiting solid‐state fluorescence is particularly important in detecting latent fingerprints (LFPs) and anti‐counterfeiting applications. Herein, we have synthesized a coumarin‐benzothiazole moiety 3‐(benzo[d]thiazol‐2‐yl)‐2H‐chromen‐2‐one (3‐BTC) to inspect its capability to visualize LFPs and work as an anti‐counterfeiting ink. The compound showed yellow‐greenish emission under UV excitation and good covertness under visible light conditions. With the help of the powder dusting method, the latent fingerprints were coated with 3‐BTC powder and images of the LFPs developed over various substrates including plastic, steel, aluminium plate, rubber, etc. under UV 365 nm light displayed good resolution be able to discern the patterns of all the levels 1–3. Apart from fresh fingerprints (taken within 10 seconds), aged (over 60 days) and incomplete eccrine LFPs were successfully visualized using 3‐BTC powder. Anti‐counterfeiting ink prepared using 3‐BTC also proved to be a promising candidate as an anti‐counterfeiting ink. Various types of paper materials, including tissue paper, printing paper, newspaper, etc. were used for evaluating 3‐BTC as a satisfactory anti‐counterfeiting ink. [ABSTRACT FROM AUTHOR]

Generally, traditional anti-counterfeiting fluorescent materials usually show a single peak under single wavelength excitation, which cannot meet the security of authentication information. Therefore, the simultaneous realization of multicolor, multiexcitation and multimodal luminescence properties remains a fascinating goal, especially in a single host. In this work, the sustained luminescent materials Ca 3 Al 2 Ge 3 O 12 :Yb3+, Er3+ (CAG:Yb3+, Er3+) were obtained, which can exhibit bright red and green luminescence with Er3+ ions under the 490 nm and near-infrared (980 nm) light excitation. The red emission dominates under the 980 nm laser irradiation, and the sample showed excellent photoluminescence (PL) and persistent luminescence (PersL) performance under the 490 nm irradiation, and the afterglow can exceed 6h. The up-conversion mechanism and emission properties of the phosphors were analytically studied, and some fluorescence-safe anti-counterfeiting patterns and multifunctional latent fingerprint (LFP) afterglow time imaging were designed as potential applications for anti-counterfeiting aspects and information storage. [Display omitted] [ABSTRACT FROM AUTHOR]

Nowadays, it is fascinating to engineer waste biomass into functional valuable nanomaterials. We investigate the production of hetero-atom doped carbon quantum dots (N-S@MCDs) to address the adaptability constraint in green precursors concerning the contents of the green precursors i.e., Tagetes erecta (marigold extract). The successful formation of N-S@MCDs as described has been validated by distinct analytical characterizations. As synthesized N-S@MCDs successfully incorporated on corn-starch powder, providing a nano-carbogenic fingerprint powder composition (N-S@MCDs/corn-starch phosphors). N-S@MCDs imparts astounding color-tunability which enables highly fluorescent fingerprint pattern developed on different non-porous surfaces along with immediate visual enhancement under UV-light, revealing a bright sharp fingerprint, along with long-time preservation of developed fingerprints. The creation and comparison of latent fingerprints (LFPs) are two key research in the recognition and detection of LFPs, respectively. In this work, developed fingerprints are regulated with an artificial intelligence program. The optimum sample has a very high degree of similarity with the standard control, as shown by the program's good matching score (86.94%) for the optimal sample. Hence, our results far outperform the benchmark attained using the conventional method, making the N-S@MCDs/corn-starch phosphors and the digital processing program suitable for use in real-world scenarios. [ABSTRACT FROM AUTHOR]

Fingerprints are unique structures made up of a combination of friction ridges. Due to the individual characteristics of fingerprints, it is used commonly used for identification. Traditionally, patent fingerprints are obtained using an ink pad. Unfortunately, the print takes time to dry on paper and sometimes the fingerprint will leave streaks on a finger and nearby surfaces. Alcohol gel and thermal paper could address this problem as the alcohol component in gel is a weak acid that can reacts with the leuco dyes present on thermal paper. Hence forth, this study intends to find an alternative method of obtaining patent fingerprints using various combinations of alcohol gels and thermal papers. Six donors were requested to deposit their fingerprints on different types of thermal paper using different brands of alcohol gel hand sanitisers. Quality scores based on CAST's grading scheme were used to determine the fingerprint quality using various combinations of thermal paper and hand sanitisers. The result showed that patent fingerprints developed using hand sanitiser and thermal paper were of lower quality than the standard (ink pad). Combination of alcohol-based hand sanitiser, which consists of 70% alcohol concentration and ATM receipt paper was found to be able to produce the best quality fingerprint among the studied combinations. Despite this result, it still indicates that fingerprints using an ink pad is still the best method to record a fingerprint. [ABSTRACT FROM AUTHOR]

This study aimed to solve environmental problems, particularly water quality and escalating crime rates. The carbon hollow nanosphere was prepared from orange peels by a reflux method. The carbon hollow nanosphere was coated with Gamma-aluminium oxide (γ-Al2O3 NPs) via the hydrothermal method. The samples were analysed using Fourier-transform infrared spectroscopy, Scanning electron microscopy, Transmission Electron Microscopy, Brunauer–Emmett–Teller, Thermogravimetric analysis, and X-Ray diffraction analysis. The surface area of γ-Al2O3/carbon hollow nanosphere nanocomposite was confirmed to be 578,039 m2/g, and the Ni2+ ions were analysed using ICP-OES. With a maximum adsorption capacity of 56.980 mg/g and a pH 9, batch adsorption experiments revealed that the uptake of Ni2+ ions best fitted the Langmuir adsorption isotherm, and the pseudo-second-order kinetics model effectively described the uptake of Ni2+ ions with a higher R2 of 0.999. Thermodynamic measurements showed the endothermic and spontaneous nature of the Ni2+ ions adsorption using the γ-Al2O3/carbon hollow nanospheres nanocomposite. The adsorbent was then used to identify latent blood fingerprints, and it was discovered that Ni2+-γ-Al2O3/carbon hollow nanosphere generated clear images of blood fingerprints on different substrates. [ABSTRACT FROM AUTHOR]

Generally, traditional anti-counterfeiting fluorescent materials usually show a single peak under single wavelength excitation, which cannot meet the security of authentication information. Therefore, the simultaneous realization of multicolor, multiexcitation and multimodal luminescence properties remains a fascinating goal, especially in a single host. In this work, the sustained luminescent materials Ca 3 Al 2 Ge 3 O 12 :Yb3+, Er3+ (CAG:Yb3+, Er3+) were obtained, which can exhibit bright red and green luminescence with Er3+ ions under the 490 nm and near-infrared (980 nm) light excitation. The red emission dominates under the 980 nm laser irradiation, and the sample showed excellent photoluminescence (PL) and persistent luminescence (PersL) performance under the 490 nm irradiation, and the afterglow can exceed 6h. The up-conversion mechanism and emission properties of the phosphors were analytically studied, and some fluorescence-safe anti-counterfeiting patterns and multifunctional latent fingerprint (LFP) afterglow time imaging were designed as potential applications for anti-counterfeiting aspects and information storage. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Formulation of water/solvent-based invisible security inks for flexo/screen printing using synthesized FNH. • Photostable & rub resistant prints with difficult to replicate but easy to authenticate security features. • Rub-induced orangish yellow emission from fluorescent cyan prints when shined with 270–400 nm light. • Cyanish green fluorescence from both rubbed & unrubbed prints upon 420–480 nm illumination. • THF or NaOH/KOH sensitive & penetrating fluorescence from the printed & rear side. • Detailed ridge characteristics achieved using FNH to develop LFPs. Smart functional materials with captivating optical properties are of immense importance due to their versatile applicability in anticounterfeiting and forensic science. A fluorene-naphthalene Schiff base (FNH) that displays aggregation induced emission, mechanofluorochromism and excitation wavelength dependent fluorescence inherent to the pristine and ground samples is synthesized. Water/solvent-based invisible security inks for flexo/screen printing were formulated using FNH as a smart pigment to check the originality of documents/branded products etc. The prints with good photostability, adherence to substrate and rub resistance are invisible in daylight showcasing multiple non-destructive and destructive techniques to authenticate the document. The inked area on UV dull paper substrate exhibits a weak emission, which is observed by the forger under UVA light. However, the user can validate the authenticity of the document by rubbing the print with hard objects, especially using a metal coin or glass rod to perceive a human eye detectable intensification in the orange fluorescence under the same illumination source. The intensity of the orange fluorescence reverts to the original, which enables the reuse of the security document after originality check. Yet another nondestructive authentication method is to observe a cyan fluorescence from the print and orangish yellow fluorescence from the rubbed printed region when shined with a 270–400 nm light source, whereas a cyanish green fluorescence both from the unrubbed and rubbed regions of the print when illuminated with a visible light source ranging from 420 to 480 nm. An additional verification through a destructive technique is to perceive red and yellow fluorescence of the ink film upon contact with THF and NaOH/KOH, respectively and a penetrating red fluorescence from the rear side of the THF-exposed printed area of the paper. The multi-level security features that cannot be easily replicated by the forger but allows a simple and easy validation process by the user are unique to FNH, used as a single pigment in the inks. Further, the applicability of the ground FNH in forensic science is established to distinctly observe Level I to II details of latent fingerprints. [ABSTRACT FROM AUTHOR]

Each person's latent fingerprints (LFP) are unique and hardly change, so LFP detection provides essential clues in forensic science. Currently, the powder dusting method is being promoted for viewing LFP due to its environmental safety; however, its low efficiency, low sensitivity, and toxicity are drawbacks, restricting its applications. To overcome these points, we proposed a NaYF 4 :Eu3+ downshifting microparticle (DSMPs) phosphor synthesized by a hydrothermal method with intense emission of ∼590–620 nm under excitation of 395 nm. We systematically studied the effect of synthesis conditions such as chelator, reaction time, temperatures, and doping concentrations on the structural, luminescent properties, and decay curves. The obtained results reveal that the crystal phase and particle morphology strongly depend on the reaction temperature. The emission properties of NaYF 4 :Eu3+ DSMPs can be significantly improved by changing the reaction temperatures and Eu doping contents. The optimized DSMPs with the most intense luminescent intensity were achieved when the phosphors were prepared at 180 οC for 24 hours, the rare earth stearate/oleic acid ratio of 1:24, and Eu doping amount of 10 mol%. This finding contributes to the suppression of substrate interference in LFP detection. The prepared NaYF 4 :Eu3+ DSMPs address the earlier limitations and show good potential for LFP detection. [ABSTRACT FROM AUTHOR]

The Eu3+-doped oxyapatite-type ZnLa 4 (SiO 4) 3 O (ZLSO) phosphors with a strong red emission were successfully synthesized. The pure phase of the phosphors with the hexagonal system was verified through X-ray diffraction. The band gap energy of the ZLSO was calculated using Materials Studio and measured using the diffuse reflection spectra. Attributed to the 7F 0 →5L 6 transition of Eu3+ at 394 nm, the prepared phosphors showed a more intense emission at 614 nm than at 590 nm, due to their asymmetric position. The optimized doping concentration of the ZLSO: x Eu3+ sample was 20 mol%, and the relevant mechanism of concentration quenching was dipole-quadrupole interaction. Notably, the ZLSO:Eu3+ phosphors exhibited preferable thermal stability, with an activation energy of 0.289 eV. The fabricated warm white light-emitting diodes (w-LEDs) with ZLSO:Eu3+ phosphors presented a high average colour rendering index (R a = 95, CCT = 5233 K). Meanwhile, the level 1–3 structures of latent fingerprints (LFPs) were distinctly displayed by ZLSO:Eu3+ samples, and security ink was successfully used to encrypt information. In summary, the highly efficient oxyapatite-type ZLSO:20 mol%Eu3+ phosphors have attractive application potential in multiple application fields, such as w-LEDs, LFPs, and security ink. • The ZnLa 4 (SiO 4) 3 O:Eu3+ phosphors are firstly synthesized via solid-state reaction. • The crystal structure of oxyapatite-type ZnLa 4 (SiO 4) 3 O belongs to the hexagonal system with space group P6 3 /m (176). • The phosphor emits bright red light excited by 394 nm. • The ZnLa 4 (SiO 4) 3 O:Eu3+ phosphors have the potential to be used for WLEDs, latent fingerprints, and security ink fields. [ABSTRACT FROM AUTHOR]

The present study reports the synthesis and characterization of Aggregation‐Induced Emission (AIE) – Excited‐state intramolecular proton transfer (ESIPT) active 2‐(2‐(4‐(4‐bromo phenyl) thiazol‐2‐yl)vinyl)phenol (BTVP). The AIE properties of BTVP in Acetone/Water solution are investigated, and fluorescent organic nanoparticles (FONs) (sizes ranging from 150–200 nm) are prepared in various water fractions (fH2O). The established visco‐chromic property suggests that the restriction of intramolecular rotation is responsible for the AIE‐ESIPT behavior of the molecule, providing a means to sense viscosity. The synthesized FONs act as fluorescence chemosensors to detect Al3+ ions via a photoinduced electron transfer (PET) mechanism. Job's, Benesi–Hildebrand method, and 1HNMR titration confirm the 1:1 binding of BTVP with the metal ion. Studies on the emission concerning pH reveal the high stability of FONs over a broad range of pH, and a gradual change in the emission wavelength for the BTVP‐Al3+ complex (BTVP‐Al) is observed, providing a means to sense pH ranging from 2–8. The solid‐state photoluminescence of BTVP is used for latent fingerprint detection, demonstrating its efficiency in detecting both primary and secondary information. Additionally, both BTVP FNOs and BTVP‐Al are used in cell imaging, where specific nuclear staining with BTVP‐Al and cytoplasm staining with BTVP are observed. [ABSTRACT FROM AUTHOR]

Latent fingerprints are a significant carrier of information for a court expert. To detect this type of forensic trace, what is necessary is a method that is easy to use, compact, and versatile. The research aimed to investigate the physicochemical properties of luminescent substances of donor–π–acceptor systems in terms of their potential use in detecting hidden fingerprints. During the research, a group of fluorene compounds consisting of the (-CH=C(CN)(COOR)) moiety was designed and successfully synthesized. The optical, electrochemical, and aggregation-induced emission properties were studied. The aggregation-induced emission of compounds has been studied in the mixture of THF (as a good solvent) and water (as a poor solvent) with different water fractions ranging from 0% to 99%. Due to the molecular structure, substances showed different affinities to organic traces. As a result, it was noticed that all compounds showed the AIE phenomenon, while during tests on latent fingerprints, it was observed that two substances had particularly forward-looking features in this field. [ABSTRACT FROM AUTHOR]

Development of latent fingerprints (LFPs) at the scene played the important role in forensic investigations by reconstructing crime trajectory and individualizing suspect. In this work, the optical sensor named TPE‐LL with aggregation‐induced emission property was constructed and used in LFPs visualization. The sensor exhibited a satisfactory linear relationship to tryptophan (Trp) in the range of 1–20 nM with the low detection limit of 0.15 nM. The samples were collected from 60 volunteers, with a total of 7200 impressed samples and 160 natural samples. Significantly, the high‐resolution fingerprints images with high fidelity and contrast containing pore features were obtained from impressed samples left on porous object for 15 days. Meanwhile, the relative complete STR typing profiles of deposited DNA were obtained and the identification rate of DNA after the develop process was 76.5 %, suggesting that the method was low destructive to DNA. The results indicated that the sensor provided promising perspectives on solving the current technical problems in the field of forensic science and technology [ABSTRACT FROM AUTHOR]

In order to detect latent fingerprints that could be damaged by liquid or powder reagents, non‐destructive processes such as gaseous reagents have been developed. In this report, we propose the use of fine mist generated when hot vapor of high‐boiling‐point liquids is rapidly cooled by surrounding air for fingermark detection. Octyl acetate (OA), 2‐phenoxyethanol (2PE), and methyl decanoate (MD) were found to efficiently produce mist when heated to 230°C. By combining these liquids with p‐dimethylaminocinnamaldehyde (DMAC) and cyanoacrylate (CN), our team demonstrated effective fluorescence staining of cyano‐treated fingermarks using DMAC/OA misting or DMAC/2PE misting, and one‐step fluorescence detection of latent fingermarks without cyanoacrylate treatment using DMAC/OA/CN misting or DMAC/MD/CN misting. Fingermark fluorescence was efficiently observed by excitation with a blue LED light (max. wavelength 470 nm) equipped with an interference filter and passing through a 520 nm long‐pass filter. We successfully obtained fluorescent images from fingermarks on several substrate materials using the developed misting method. [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]

Forensic chemistry plays a pivotal role in modern criminal investigations, providing invaluable insights into a diverse array of evidentiary materials. This review article offers a general exploration of a few key facets within the realm of forensic chemistry, encompassing fingerprint analysis, and biological fluid assessment. Each of these domains contributes to the intricate puzzle of forensic investigations. In this review, fingerprint analysis serves as a cornerstone in identifying individuals, with advancements in fingerprint development techniques enhancing the accuracy and reliability of identification. The analysis of seized drug samples offers crucial insights into the crime scene and gives vital clues as to which drug of abuse is responsible for the crime, in essence, this review amalgamates the multifaceted contributions of forensic chemistry, showcasing its pivotal role in unraveling complex criminal scenarios. [ABSTRACT FROM AUTHOR]

We demonstrate here a simple approach to integrate photochromic properties with aggregation‐induced emission behavior via supramolecular self‐assembly with the aim to build a new type of photoswitchable materials. We have designed and synthesized two unsymmetrical peptide‐bridged naphthalimide–dithienylethene dyads, each composed of naphthalimide (NI), an alkyl (CH2)n [n=2,8] chain (Cn), a dipeptide of phe‐phe scaffold, and an unsymmetrical dithienylethene (DTE) moiety (NI‐Cn‐pep‐DTE; 6: n=2; 7: n=8). Dyads 6 and 7 show comparable photo‐isomerization speed and rate constant (K) values for cyclization (75 s, K=0.049 s−1 for 6, 65 s, K=0.056 s−1 for 7) and cycloreversion (105 s, K=0.037 s−1 for 6, 100 s, K=0.023 s−1 for 7) accompanied by a noticeable naked‐eye color change from pale yellow (6 o/7 o; open forms) to purple (6 c/7 c; closed forms). Both compounds show considerably high fatigue resistance for at least 45 cycles without loss of sensitivity and compound 7 exhibits fluorescence photoswitching performance in solution, solid state, as well as in gel form through a FRET mechanism. The developed dithienylethene (DTE)‐based material was applied in latent fingerprints (LFPs) and in anti‐counterfeiting technology in a non‐invasive manner. [ABSTRACT FROM AUTHOR]

In recent years, electrochemiluminescence (ECL) has received enormous attention and has emerged as one of the most successful tools in the field of analytical science. Compared with homogeneous ECL, the heterogeneous (or solid-state) ECL has enhanced the rate of the electron transfer kinetics and offers rapid response time, which is highly beneficial in point-of-care and clinical applications. In ECL, the luminophore is the key element, which dictates the overall performance of the ECL-based sensors in various analytical applications. Tris(2,2'-bipyridyl)ruthenium (II) complex, Ru(bpy)32+, is a coordination compound, which is the gold-standard luminophore in ECL. It has played a key role in translating ECL from a "laboratory curiosity" to a commercial analytical instrument for diagnosis. The aim of the present review is to provide the principles of ECL and classical reaction mechanisms—particularly involving the heterogeneous Ru(bpy)32+/co-reactant ECL systems, as well as the fabrication methods and its importance over solution-phase Ru(bpy)32+ ECL. Then, we discussed the emerging technology in solid-state Ru(bpy)32+ ECL-sensing platforms and their recent potential analytical applications such as in immunoassay sensors, DNA sensors, aptasensors, bio-imaging, latent fingerprint detection, point-of-care testing, and detection of non-biomolecules. Finally, we also briefly cover the recent advances in solid-state Ru(bpy)32+ ECL coupled with the hyphenated techniques. [ABSTRACT FROM AUTHOR]

Red-color emitting carbon dots (CDs) are of tremendous interest in the field of materials discipline owing to their promising applications in the domains of forensic applications, lighting, fingerprinting, imaging, sensing, etc. However, the unavailability of mass production of red-emitting CDs restricts their potential uses. As a result, we used a solid-state approach for producing red-color emitting CDs. The benefits of synthesized CDs include large-scale manufacturing, red-color fluorescence in the aggregated state, and afterglow emission. Surprisingly, the developed CDs showed phosphorescence without aggregating any matrix. The fluorescence and phosphorescence emissions were observed at 574 and 585 nm, respectively. The presence of graphitic-N is responsible for red-color emission; simultaneously, it seems that nitrogen helps in extending the sp2-conjugation. Mutually, the C＝N bond and strong π–π interactions in the aggregated form are responsible for stabilizing the excited triplet state. The carbon dot powder displayed unchanging phosphorescence with a lifespan of 43.71 ms. Further, the produced CDs have been used in anticounterfeiting, latent fingerprint detection, and in solid-state lighting. It is worth noticing that synthesized carbon dots detect even the third level of fingerprint patterning. In lighting, the obtained CIE coordinate is (0.40, 0.37) with a CRI of 98. [ABSTRACT FROM AUTHOR]

We have reported a novel dibromo allyl-substituted perylene diimide (PDI 2) as a near-IR emitter with 99.53% color purity and ϕ = 0.0385. PDI 2 showed a morphology of a thick film (4–5 nm) with holes of radius 20–40 nm and a depth of 4–7 nm. PDI 2 has been used for the daylight and fluorescence imaging of latent fingerprints up to levels 1–3 on different colored porous and non-porous surfaces. [ABSTRACT FROM AUTHOR]

Fingerprints are one of the most important scientific proof instruments in solving forensic cases. Identification in fingerprints consists of three levels based on the flow direction of the papillary lines at the first level, the minutiae points at the second level, and the pores at the third level. The inadequacy of existing imaging systems in detecting fingerprints and the lack of pore details at the desired level limit the widespread use of third-level identification. The fact that fingerprints with images based on pores in the unsolved database are not subjected to any evaluation criteria and remain in the database reveals the importance of the study to be carried out. In this study, different from classical fingerprint identification methods, a direct pore-based identification system for fingerprint matching is proposed with the dataset created by using the Docucenter Nirvis device and Projectina Image Acquisition-7000 software as a hyperspectral imaging system where pores were visualized more clearly. Although difficult from an operational perspective, the pores in the 800 fingerprints in the database were manually marked for the accuracy of the results. Next, by using a scoring based on iterative closest point algorithm, latent fingerprints were found. Results suggest that the higher the number of pores examined and the more accurately the pores were marked, the higher the hit score. At the same time, query results showed that the scores of other sequential fingerprints in the database which came after the matching fingerprint were even lower. [ABSTRACT FROM AUTHOR]

The DNPG, which consists of naphthalimides at terminal positions of pentaethylene glycol chain, was non covalently doped on nanoporous silica (SiO2) and has been used as fluorescent powder for imaging of latent fingerprints (LFPs) on porous and non‐porous surfaces. We have successfully demonstrated the application of DNPG@SiO2 fluorescent powder for visualization of level 1 (indexing), level 2 (minutiae points) and level 3 (sweat pores). We also attempted to establish the identity of the subject (person) in case studies on 12 subjects. The CIE‐1931 coordinates (x,y) of 0.2, 0.3 of DNPG showed green colour with 49.4 % purity and it possessed low cytotoxicity (IC50=139.5 uM). [ABSTRACT FROM AUTHOR]

Novel naphthalimide based fluorescent dye NI‐1 possess (i) high quantum yield, (ii) blue emission (λem=450 nm), (iii) CIE coordinate (x=0.21, y=0.35) with 39 % blue colour purity in solid state, (iv) photochemical and thermal stability up to 200 oC and (v) low cytotoxicity to normal cells L929. NI‐1 was doped in nano porous silica and used as fluorescent powder for imaging of latent fingerprints (LFPs) on coloured surfaces, barcode, wood, brick, leaf and engraved steel beside other common household porous and nonporous surfaces. We demonstrated visibility of levels 1–3 on ceramic tile, glass, paper, steel, iron and compact disc using NI‐1 doped fluorescent silica powder. Furthermore, LFPs developed with NI‐1 were successfully lifted from different surfaces using adhesive tape for documentation and archiving purposes. To mimic the automated fingerprint identification system (AFIS), we manually screened fingerprints from 16 subjects to identify the unknown subject. The unique minutiae points such as long hook, opposite bifurcation, crossbar, cross over, dock, triple bifurcation, lake and spikes were observed beside other 16 minutiae points. [ABSTRACT FROM AUTHOR]

Latent fingerprint collection and analysis remain a critical forensic technique in a variety of settings globally. However, the quality of deposited fingermarks depends on a plethora of extrinsic and intrinsic factors, one of which includes how skin diseases or conditions can affect development and recovery of latent fingerprint impressions. One such condition is hypohidrotic ectodermal dysplasia (HED), which involves underdevelopment of partial or complete absence of eccrine glands. This study aimed to establish whether recovered fingermark quality was different between HED-positive and unaffected control individuals, and whether quality of developed marks from HED-positive individuals was higher using chemical versus powder methods. Control and HED-positive individuals deposited fingermarks on three different substrates and two development methods were used per substrate. Developed fingermarks were scored qualitatively and compared statistically. Generally, HED-positive individuals produced significantly lower quality marks than the control group, and powder development (either standard or magnetic black) produced significantly poorer quality fingermarks than chemical methods across most substrates for both HED-positive and control group individuals. Taken together, these results support fingerprint examiners using chemical enhancement techniques preferentially where faint fingermarks are encountered. These results contribute important insight for improving best practice and maximizing evidence recovery from faint fingerprint impressions. [ABSTRACT FROM AUTHOR]

For fingerprint-involved forensic investigations, cyanoacrylates and inorganic nanophosphors are mostly used for fingerprint visualization. However, methods to simultaneously report fingerprint images and the corresponding specific chemical information have yet to be realized. In this work, chemical visualization of the analytes in fingerprints is achieved through surface-enhanced Raman spectroscopy (SERS) measurements with the aid of spray-dispersed gold nanorods (AuNRs). The optimal coverage of AuNRs was studied by theoretical simulations and experimental operations. A rapid sampling of fingerprints with the chemical of interest was developed by tuning the spray parameters. In particular, the SERS imaging of methamphetamine in fingerprint latent was attempted by addressing the SERS spectral features of methamphetamine. This chemical visualization method reflects both the graphical and chemical characteristics of fingerprints in a single batch measurement, in which methamphetamine can be detected and mapped at the concentration of 10−5 M. The data processing approach was also modified by employing relevant logical judgments. The improved SERS images with sharpened patterns of fingerprints were obtained by involving the scored multi-peak judgments. [ABSTRACT FROM AUTHOR]

The synthesis, structural characterization, exfoliation, and photophysical studies of two-dimensional (2-D) lanthanide phosphonates, named Ln(m-pbc) ; [Ln(m-Hpbc)(m-H2pbc)(H2O)] (Ln = Eu, Tb; m-pbc = 3-phosphonobenzoic acid) based on the phosphonocarboxylate ligand, are reported. These compounds are neutral polymeric 2D layered structures with pendent uncoordinated carboxylic groups between layers. The nanosheets were obtained by a top-down strategy involving sonication-assisted solution exfoliation and characterized by atomic force microscopy and transmission electron microscropy, showing lateral dimensions from nano- to micro-meter scales, and thicknesses down to several layers. The photoluminescence studies demonstrate that the m-pbc ligand acts as an efficient antenna toward Eu and Tb(III) ions. The emission intensities of dimetallic compounds are clearly enhanced after incorporation of Y(III) ions due to the dilution effect. Ln(m-pbc)s were then applied for labelling latent fingerprints. It is worth noting that the reaction between active carboxylic groups and fingerprint residues benefits the labelling, showing efficient imaging for fingerprints on all kinds of material surfaces. [ABSTRACT FROM AUTHOR]

[Display omitted] Taking the same developing strategy for different types of latent fingerprints is helpful in improving the efficiency of criminal investigation. Here we advanced a new strategy based on amino-functionalized poly(p -phenylenevinylene) nanoparticles (PPV-brPEI NPs) in aqueous colloidal solution as the developing reagent. The desirable amino functionality and strong emission of NPs were simultaneously realized by adding branched polyethyleneimine (brPEI) during the process of thermal elimination of the PPV polymer precursor. The NPs were demonstrated to have negligible effects on the extraction of biological information from DNA. Using the PPV-brPEI NPs-soaked cotton pad, both latent sebaceous fingerprints (LSFPs) and latent blood fingerprints (LBFPs) can be effectively developed on different nonporous substrates. This strategy was highly sensitive and effective for aged, contaminated and moldy fingerprints. Additionally, the developed fingerprints could tolerate humidity environment and the alcohol atmosphere. The mechanism investigation suggests that interaction between PPV-brPEI NPs and sebum ingredients contributes to the development of LSFPs and interaction between PPV-brPEI NPs and proteins in blood contributes to the development of LBFPs, but the former is not as stable as the latter. This work provides a simple, environment/operator-friendly strategy for efficient fingerprint development, which is very promising for practical criminal investigations. [ABSTRACT FROM AUTHOR]

As advanced fingerprint powders, fluorescent materials generally provide high sensitivity and improved contrast on the pigments or patterned surface, with high resolution. In this study, ZnO nanoparticles are used as fluorescent materials and are homogeneously embedded into SiO2 matrix to prepare ZnO@SiO2 nanocapsules. Compared with conventional methods, ZnO@SiO2 nanocapsules are fabricated using the transparent ethanol solution of ZnO NPs and n‐Octyltriethoxysilane without any surfactants. Interestingly, a large number of ZnO NPs can be homogeneously embedded in the silica matrix, reducing the aggregation‐induced quenching effect. The maximum emission of the ZnO@SiO2 nanocapsules powder is located at 530 nm under 325 nm irradiation, and the photoluminescence intensity and the sensitivity of latent fingerprints development depend on the quantity of ZnO NPs in the composites. The prepared fluorescent ZnO@SiO2 nanocapsules show outstanding property applied as effective fluorescent eikonogens for the high‐sensitivity visualization of latent fingerprints on different porous and non‐porous substrates. It has been demonstrated that ZnO@SiO2 nanocapsules compounds combine the admirable adhesion of silica powders to fingerprint residues with the excellent photoluminescence properties of ZnO to form a promising light‐emitting material for fingerprint. [ABSTRACT FROM AUTHOR]

A convenient and mild method for preparing multicolor carbon dots (CDs) using the solvothermal process and extraction has been developed. After doping CDs as the cross-linking agent into γ-(2,3-epoxypropoxy)propytrimethoxysilane solution, orange, yellow, and blue emitting powders were fabricated, which effectively avoid aggregation-caused quenching and emit bright luminescence. By introducing oily chain segments, the interaction between the fluorescent powder and fingerprint residue is improved as well as the imaging ability of latent fingerprints. Level 1–3 features can be extracted using the CD powder developed fingerprints. Additionally, seven substrates with different surface appearance, colours, and interference were chosen to deposit on fingerprints, in which all the substrates have a good combination with the CD powder and showed excellent contrast and visibility. Notably, the as-prepared CDs can be used for acetate ion (AcO−) sensing. The CDs exhibit an efficient response to AcO− by an "on–off" switching strategy. As a sensing probe, the CDs exhibit a wide concentration range (3 × 10−7–3 × 10−3 M) of response to AcO− with a low fluorescence response threshold (0.3 μM). [ABSTRACT FROM AUTHOR]

In recent years, the application of biocompatible and non-toxic nanomaterials for the detection of fingerprints has become the major interest in the forensic sector and crime investigation. In this study, waste chickpea seeds, as a natural resource, were bioprocessed and utilized for the synthesis of non-toxic graphene nano-sheets (GNSs) with high fluorescence. The graphene GNS were synthesized via pyrolysis at high temperatures and were characterized by TEM, XPS, fluorescence and UV-Vis spectroscopy, and FTIR analysis. The GNS exhibited excitation-independent emission at about 620 nm with a quantum yield of over 10% and showed more distinct blue light under a UV lamp. Biocompatibility of the synthesized GNS in terms of cell viability (88.28% and 74.19%) was observed even at high concentrations (50 and 100 mg/mL), respectively. In addition, the antimicrobial properties of the synthesized GNS-based coatings were tested with the pathogenic strain of Bacillus cereus via live/dead cell counts and a plate counting method confirming their biocompatible and antimicrobial nature for their potential use in safe fingerprint detection. The developed chickpea-originated fluorescent GNS-based spray coatings were tested on different surfaces, including plastic, glass, silicon, steel, and soft plastic for the detection of crime scene fingerprints. Results confirmed that GNS can be used for the detection of latent fingerprints on multiple non-porous surfaces and were easy to detect under a UV lamp at 395 nm. These findings reinforce the suggestion that the developed fluorescent GNS spray coating has a high potential to increase sensitive and stable crime traces for forensic latent fingerprint detection on nonporous surface material. Capitalizing on their color-tunable behavior, the developed chickpea-originated fluorescent GNS-based spray coating is ideal for the visual enhancement of latent fingerprints. [ABSTRACT FROM AUTHOR]

Improving interoperability in contactless‐to‐contact fingerprint matching is a crucial factor for the mainstream adoption of contactless fingerphoto devices. However, matching contactless probe images against legacy contact‐based gallery images is very challenging due to the presence of heterogeneity between these domains. Moreover, unconstrained acquisition of fingerphotos produces perspective distortion. Therefore, direct matching of fingerprint features suffers severe performance degradation on cross‐domain interoperability. In this study, to address this issue, the authors propose a coupled adversarial learning framework to learn a fingerprint representation in a low‐dimensional subspace that is discriminative and domain‐invariant in nature. In fact, using a conditional coupled generative adversarial network, the authors project both the contactless and the contact‐based fingerprint into a latent subspace to explore the hidden relationship between them using class‐specific contrastive loss and ArcFace loss. The ArcFace loss ensures intra‐class compactness and inter‐class separability, whereas the contrastive loss minimises the distance between the subspaces for the same finger. Experiments on four challenging datasets demonstrate that our proposed model outperforms state‐of‐the methods and two top‐performing commercial‐off‐the‐shelf SDKs, that is, Verifinger v12.0 and Innovatrics. In addition, the authors also introduce a multi‐finger score fusion network that significantly boosts interoperability by effectively utilising the multi‐finger input of the same subject for both cross‐domain and cross‐sensor settings. [ABSTRACT FROM AUTHOR]