Luminescent Markers Research Articles

Identification of Luminescent Markers for Gunshot Residues: Fluorescence, Raman Spectroscopy, and Chemometrics

Gunshot residue (GSR) is an evidence of major importance in firearm-related crimes. The recent introduction of nontoxic ammunition has made impossible the characterization of GSR particles by the current methods employed by forensic experts. To overcome this drawback, the introduction of luminescent markers was proposed, allowing on-site visual detection of luminescent gunshot residue (LGSR) at the crime scene. Three different luminescent markers coordinated with europium for specific and selective encoding of ammunition have been proposed. To promote a variety of versatile tools for GSR analysis, spectroscopic techniques combined with chemometric methods can be applied to achieve a reliable, fast, and nondestructive means to identify LGSR and discriminate among the different markers. Luminescence (emission and excitation), normal, and resonance Raman spectroscopies associated with principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA) were evaluated. The classification model using the complementary information on emission and excitation spectra, a.k.a. data fusion, provided a 100% correct classification for all markers. A comprehensive study has been developed to show that the insertion of luminescent markers enables not only the easy localization of GSR residues but also the possibility of ammunition encoding through the use of multivariate classification methods.

Analysis of Luminescent Gunshot Residue (LGSR) on Different Types of Fabrics.

The collection of gunshot residue on fabric can be an arduous task due to the microscopic size of particles (blind collection) and sheddability of some fabrics. The introduction of luminescent markers and consequent formation of luminescent gunshot residue (LGSR) can facilitate this analysis. In this study, different fabrics were analyzed in order to verify the persistence of the LGSR on them, the possibility of collecting and analyzing particles by video spectral comparator (VSC) and SEM/EDS. Also, different colored fabrics were used as targets in order to investigate influence of fabric color on LGSR visualization. Furthermore, the influence of the fabric type in the distribution of the LGSR deposited around the projectile´s hole entrance was evaluated. The fabric sheddability did not alter collection of the particles or analysis. It was possible to observe and collect LGSR on all tested fabrics, even after the fabric had been shaken, or in colored fabrics.

Surprising synergy of dual translation inhibition vs. Acinetobacter baumannii and other multidrug-resistant bacterial pathogens

BackgroundMultidrug-resistant (MDR) Acinetobacter baumannii infections have high mortality rates and few treatment options. Synergistic drug combinations may improve clinical outcome and reduce further emergence of resistance in MDR pathogens. Here we show an unexpected potent synergy of two translation inhibitors against the pathogen: commonly prescribed macrolide antibiotic azithromycin (AZM), widely ignored as a treatment alternative for invasive Gram-negative pathogens, and minocycline, among the current standard-of-care agents used for A. baumannii. MethodsMedia-dependent activities of AZM and MIN were evaluated in minimum inhibitory concentration assays and kinetic killing curves, alone or in combination, both in standard bacteriologic media (cation-adjusted Mueller-Hinton Broth) and more physiologic tissue culture media (RPMI), with variations of bicarbonate as a physiologic buffer. Synergy was calculated by fractional inhibitory concentration index (FICI). Therapeutic benefit of combining AZM and MIN was tested in a murine model of A. baumannii pneumonia. AZM + MIN synergism was probed mechanistically by bacterial cytological profiling (BCP), a quantitative fluorescence microscopy technique that identifies disrupted bacterial cellular pathways on a single cell level, and real-time kinetic measurement of translation inhibition via quantitative luminescence. AZM + MIN synergism was further evaluated vs. other contemporary high priority MDR bacterial pathogens. FindingsAlthough two translation inhibitors are not expected to synergize, each drug complemented kinetic deficiencies of the other, speeding the initiation and extending the duration of translation inhibition as verified by FICI, BCP and kinetic luminescence markers. In an MDR A. baumannii pneumonia model, AZM + MIN combination therapy decreased lung bacterial burden and enhanced survival rates. Synergy between AZM and MIN was also detected vs. MDR strains of Gram-negative Klebsiella pneumoniae and Pseudomonas aeruginosa, and the leading Gram-positive pathogen methicillin-resistant Staphylococcus aureus. InterpretationAs both agents are FDA approved with excellent safety profiles, clinical investigation of AZM and MIN combination regimens may immediately be contemplated for optimal treatment of A. baumannii and other MDR bacterial infections in humans. FundNational Institutes of Health U01 AI124326 (JP, GS, VN) and U54 HD090259 (GS, VN). IC was supported by the UCSD Research Training Program for Veterinarians T32 OD017863.

Monitoring Ethylene in Plants: Genetically Encoded Reporters and Biosensors

AbstractPhytohormone ethylene regulates numerous aspects of plant physiology, from fruit ripening to pathogen responses. The molecular basis of ethylene biosynthesis and action has been investigated for over 40 years, and a combination of biochemistry, genetics, cell, and molecular biology have proven successful at uncovering the core machinery of the ethylene pathway. A number of molecular tools have been developed over the years that enable visualization of the sites of ethylene production and response in the plant. Genetically encoded biosensors take advantage of reporter proteins, i.e., fluorescent, luminescent, or colorimetric markers, to highlight the tissues that make, perceive, or respond to the hormone. This review describes the different types of biosensors currently available to the ethylene community and discusses potential new strategies for developing the next generation of genetically encoded ethylene reporters.

A new photoluminescent terbium(III) coordination network constructed from 1,2,4,5-benzenetetracarboxylic acid: Synthesis, structural characterization and application as a potential marker for gunshot residues

A novel terbium(III) coordination network (CN) of formula [TbHbtec]n1, constructed from 1,2,4,5-benzenetetracarboxylic acid (H4Btec) and Tb3+ ions, has been obtained under hydrothermal conditions. Single crystal X-ray diffraction and topological studies revealed the crystal structure of CN 1 involves a cubic primitive network with topology pcu-αPo, uninodal and with point symbol (412. 63). In the crystal structure, the ligand is monoprotonated (Hbtec3−) with six Hbtec3− adopting the monodentate, bidentate chelating and bidentate chelating-bridging coordination modes, leading to the formation of a 3-D coordination network. Solid state luminescence spectrum showed the characteristic 5D4 → 7FJ (J = 6–2) transitions of the Tb3+ ion upon excitation in the Hbtec3− singlet levels, revealing that the ligand Hbtec3− is a good sensitizer for the intense green emission of Tb3+ ions. Thermogravimetric analysis (TGA) showed CN 1 has exceptional thermal stability decomposing at temperatures higher than 470 °C. Taking advantage of its excellent thermal and optical properties, the [TbHbtec]n was tested as luminescent marker for gunshot residues, opening the possibility of using this compound in forensic analysis of crime scenes.

Luminescence of coprecipitated titanium white pigments: Implications for dating modern art.

Material analysis of cultural artifacts can uncover aspects of the creative process and help determine the origin and authenticity of works of art. Technical studies on abstract expressionist paintings revealed a luminescence signature from titanium white paints whose pigments were manufactured by coprecipitation with calcium or barium sulfate. We propose that trace neodymium present in some ilmenite (FeTiO3) ores can be trapped in the alkaline earth sulfate during coprecipitation, generating a luminescent marker characteristic of the ore and process. We show that the luminescence is linked to a specific ilmenite source used in historic TITANOX pigments, is not present in pigments produced by more advanced chemistries, and provides dating information. Facile Raman-based detection of this luminescence, along with characteristic peaks of rutile, anatase, calcium sulfate, or barium sulfate, can identify the type of titanium white pigment and narrow its manufacture date range.

Stable luminescent markers from sugar for patterning and pH sensing applications

In this article, the luminescence feature of sugar derived carbon dots is exploited for the fabrication of luminescent marker and pH sensor. A new environment benign material, Gum Arabic (GA) is introduced as a potential binder for luminescent markers for the first time. The marker was found to be highly photo stable and exhibited considerable adherence over a wide range of substrates. The luminescence intensity of the system is sequentially decreased with increment in pH of the medium, which enabled pH sensing using the system in the wide range of –10. 2-10.

Monodispersed Spherical Nanoparticles GdxSiyOz:Eu3+ for Magnetic Resonance Tomography and Optical Imaging

The melt method is used for synthesizing monodispersed spherical silica nanoparticles Gdx-SiyOz:Eu3+. The particle diameter is 450 nm, and the standard deviation does not exceed 5%. The nanoparticles have a line luminescence spectrum with a dominant band at 614 nm. The effect of a constant magnetic field up to 15 T on the intensity and shape of the luminescence spectra of Eu3+ ions is studied. It is shown that the obtained material has a stable photoluminescence, the intensity of which does not depend on the magnetic field in the entire studied range. The synthesized nanoparticles GdxSiyOz : Eu3+ are promising for use as a contrast agent for magnetic resonance tomography and luminescent marker.

Image-Processing Software for High-Throughput Quantification of Colony Luminescence.

Many microbiological assays include colonies that produce a luminescent or fluorescent (here generalized as "luminescent") signal, often in the form of luminescent halos around the colonies. These signals are used as reporters for a trait of interest; therefore, exact measurements of the luminescence are often desired. However, there is currently a lack of high-throughput methods for analyzing these assays, as common automatic image analysis tools are unsuitable for identifying these halos in the presence of the inherent biological noise. In this work, we have developed CFQuant-automatic, high-throughput software for the analysis of images from colony luminescence assays. CFQuant overcomes the problems of automatic identification by relying on the luminescence halo's expected shape and provides measurements of several features of the colonies and halos. We examined the performance of CFQuant using one such colony luminescence assay, where we achieved a high correlation (R = 0.85) between the measurements of CFQuant and known protein expression levels. This demonstrates CFQuant's potential as a fast and reliable tool for analysis of colony luminescence assays.IMPORTANCE Luminescent markers are widely used as reporters for various biologically interesting traits. In colony luminescence assays, the levels of luminescence around each colony can be used to compare the levels of traits of interest for different strains, treatments, etc., using quantitative measurements of the luminescence. However, automatic methods of obtaining this data are underdeveloped, making this a laborious manual process, especially in analyzing large numbers of colonies. The significance of this work is in developing an automatic, high-throughput tool for quantitative analysis of colony luminescence assays, which will allow fast collection of qualitative data from these assays and thus increase their overall usability.

Монодисперсные сферические наночастицы Gd-=SUB=-x-=/SUB=-Si-=SUB=-y-=/SUB=-O-=SUB=-z-=/SUB=- : Eu-=SUP=-3+-=/SUP=- для магнитно-резонансной томографии и оптической визуализации

AbstractThe melt method is used for synthesizing monodispersed spherical silica nanoparticles Gd_ x -Si_ y O_ z :Eu^3+. The particle diameter is 450 nm, and the standard deviation does not exceed 5%. The nanoparticles have a line luminescence spectrum with a dominant band at 614 nm. The effect of a constant magnetic field up to 15 T on the intensity and shape of the luminescence spectra of Eu^3+ ions is studied. It is shown that the obtained material has a stable photoluminescence, the intensity of which does not depend on the magnetic field in the entire studied range. The synthesized nanoparticles Gd_ x Si_ y O_ z : Eu^3+ are promising for use as a contrast agent for magnetic resonance tomography and luminescent marker.

Ammunition encoding by means of co-doped luminescent markers

In forensics, the identification of gunshot residues (GSR) is a crucial point in firearm crime investigations. However, there is a lack of analytical methodologies to characterize the residues produced by non-toxic ammunition (NTA). To overcome this drawback, researchers have proposed the introduction of luminescent and chemical markers into ammunition. Luminescent markers, besides overcoming problems of NTA analysis, aid to identify and collect GSR by direct visualization of luminescent residues under UV radiation. Furthermore, the development of new markers with unique compositions has opened new perspectives about encoding ammunition. In this work, we propose the use of eight co-doped lanthanide metal-organic frameworks (Ln-MOF) [Y1−XLnX(BTC)] (wherein BTC = trimesic acid) containing discrete concentration levels of Eu3+, Tb3+, Sm3+ and/or Yb3+ ions, as chemical barcodes for ammunition. To assess the method efficiency, we performed blind tests in which neither the shooters and the analyst had knowledge about the marker present in each cartridge that was fired. After shots, the residues were collected and analyzed by scanning electron microscopy coupled with energy dispersive spectroscopy (SEM/EDS) and video spectral comparator (VSC) to identify the marker used. As result, all of the markers were correctly identified. In addition, correlation between the residues collected at different locations (as hands, firearm and shooting area) was possible. Therefore, the encoding method proposed proved to be a powerful analytical tool for firearm crime investigations, providing a level of information that cannot be achieved with the current methodologies.

Fluorescein‐Loaded Solid Lipid Nanoparticles Based on Monoamine Pillar[5]arene: Synthesis and Interaction with DNA

AbstractPresent research is the first example to use pillar[5]arene for creation fluorescein‐loaded solid lipid nanoparticles and release dye during interaction with DNA ‐ potential delivery system of the imaging agent. Monoamine functionalized pillar[5]arene was synthesized for preparation of the solid lipid nanoparticles (SLN) with/without luminescent marker (fluorescein). Interestingly, presence of a single tail‐group in the pillar[5]arene has opened wide opportunities for the formation of the various types of pillararene‐based assemblies, i. e., pseudorotaxanes, supramolecular polymers and SLNs, varying the solvents.

Clinical Experience of Luminescent Diagnostics of Precancerous Diseases and Cervical Cancer

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Luminescence Method for Studying the Formation and Stability of Macromolecular Complexes of Transition Metals with Carboxyl-Containing Polymers in Organic Solvents

Quenching of the luminescence of carboxyl-containing polymer molecules containing a luminescent marker by transition metal ions (Cu2+, Ni2+) is observed not only in aqueous and aqueous-salt solutions, but also in polar organic solvents (methanol, ethanol, dimethylformamide). In dilute solutions, quenching refl ects binding of metal ions with the polymer and changes in the degree of filling of the polymer carboxyl groups with transition metal ions quenching the luminescence. The equilibrium stability constant of the formed macromolecular metal complex in organic media can be quantitatively estimated from the quenching effect using the relationships that follow from the law of mass action. The formation and stability of Cu2+ and Ni2+ complexes with polymethacrylic acid in protic (methanol, ethanol) and aprotic (dimethylformamide) solvents at low polymer concentrations (0.4–0.02 mg mL–1) were studied using the quenching effect. In methanol, in contrast to ethanol and dimethylformamide, two mechanisms of binding of transition metal ions with different equilibrium stability constants of the complexes ( $${K_{{1^{st}}}}$$ > 3 × 109 and $${K_{{2^{st}}}}$$ ≈ 106–104) were revealed. The infl uence exerted on the stability of the complexes and on the complexation mechanism by the nature and acidity of the organic solvent, polymer concentration, kind of the transition metal ion quenching the luminescence, and NaOH and HCl additions was studied. The results obtained demonstrate the efficiency of the luminescence method used and prospects for its further use for studying polymer systems containing transition metal ions in organic solvents.

Ln2(BDC)3(H2O)4]n: A low cost alternative for GSR luminescent marking

This paper reports on the development of low cost luminescent markers for gunshot residue (GSR) identification by a new room temperature precipitation synthesis route. These markers are metal-organic frameworks (MOFs) formed by the ligand 1,4-H2BDC (teraphthalic acid) and the metals Zn2+, Eu3+ and Tb3+. The MOFs were synthesized by precipitation, using different ratios of zinc and lanthanides (1–100%). The synthesized MOFs were added to 9 mm NTA gunpowder and, after shots were fired, luminescent residues (LGSR) were visualized under UV radiation. The residues were collected and characterized by non-destructive techniques such as SEM-EDS and emission spectroscopy. All MOFs presented high luminescence. However, those with levels of Eu3+ above 10% or Tb3+ above 5% presented the best cost-benefit. Comparing with the marker containing only lanthanide ions, this represents a cost reduction of up to 7-times. Besides, the precipitation synthesis represents an innovation in developing crystalline, high luminescent and stable luminescent markers for GSR identification.

The multiplex analysis of drug medicinals on the basis of technology of immunochips Phosphan.

The new technique of multiplex qualitative analysis of narcotic, psychotropic remedies is developed on the basis of technology Phosphan using immunochips in the format of standard 96-wells plates, monoclonal antibodies to narcotic compounds and Pt-coproporphyrin as a long luminescent marker. The multiplex analysis was implemented using 20 mkl of human biological fluid (urine, blood serum or saliva) of 2 discs of 3.2 mm in diameter made of dried urine spot on paper. No preliminary processing or dilution of analyzed sample is required. The large range of measured concentrations was demonstrated under high sensitivity of analysis: 1 ng/ml of morphine and methadone, 0.5 ng/ml of barbiturates, 2 ng/ml of benzoylecgonine, methamphetamine, cannabinoids and benzodiazepines, 8 ng/ml amphetamine at variability of results no more than 15%. The approbation of technique was implemented using valid samples of urine (n=197) and blood serum (n=98) demonstrated that the technique permits to detect properly opiates, cocaine, cannabinoids, methadone, benzodiazepine, barbiturates and amphetamines at absence of false positive results in case of analysis of samples containing non-narcotic medications. The results of study of samples of dried urine spot on paper (n=50) well coincided with the results of analysis of fluid samples for all analyzed analytes. On the basis of proposed multiplex analysis a test-system Narc-Phosphan was developed for quantitative studying simultaneously up to 96 samples of various biological fluids, including as dried spots on paper. The analysis demonstrated high sensitivity, specificity and exactness during detection of the most prevailed narcotic substances that permits to propose this technique as a primary test during mass check-ups of population with purpose of detection of drug abuse, especially at the earlier stage.

Nanoparticle Probes for Super‐Resolution Fluorescence Microscopy

AbstractThe Abbe resolution limit of ∼200 nm of conventional light‐optical microscopy greatly restricts the observation of subcellular processes. This Abbe resolution barrier has been surpassed by super‐resolution fluorescence microscopy methods that use time as an additional dispersing dimension. Light irradiation can be employed to externally control the emission properties of the luminescent markers, or spontaneous fluctuations of the emission of individual emitters can be analyzed. Here we review the development and application of light‐emitting nanoscale particles for super‐resolution imaging and discuss their (photo)physical and (photo)chemical characteristics to offer guidance in the selection of the optimal nanoparticle marker for an intended super‐resolution imaging experiment.

2D-BN nanoparticles as a spectroscopic marker and drug delivery system with protection properties.

An application of 2D-BN nanoparticles as a spectroscopic marker, weak luminescent marker and anticancer drug (doxorubicin, DOX) delivery system with protection properties was studied for the LNCaP strains of cancer cells using FTIR and Raman spectroscopy for analysing the cancer cells, cells with BN, the cancer cells with DOX, and the cancer cells with BN nanoparticles loaded by DOX. Study of IR absorption and Raman spectra of the LNCaP strains of cancer cells incubated with 2D-BN nanoparticles for 1 hour showed that the 2D-BN nanoparticles could pass through the cell membrane and localize inside the membrane or close to the membrane in the cytoplasm of the cells. We registered the spectra of the disturbed lipids during the DOX-2D-BN passing through the membrane. After incubation for 2 hours and more, spectral changes in other structural components of the cell (nuclei, cytoplasm, mitochondria) can be registered. Confocal microscopy showed that a gold nanostructured support enhances the fluorescence of the cancer cells with 2D-BN as well as that with DOX, however the double action of 2D-BN and DOX on the cancer cells aggravates the emission property of the studied system. An MTT test showed that the toxicity of DOX on the 2D-BN nanoparticles is less than that on the reference cells, and at the same time the efficiency of the DOX action on the cancer cells does not change.

Single-step synthesis of Er3+ and Yb3+ ions doped molybdate/Gd2O3 core–shell nanoparticles for biomedical imaging

Nanostructures as color-tunable luminescent markers have become major, promising tools for bioimaging and biosensing. In this paper separated molybdate/Gd2O3 doped rare earth ions (erbium, Er3+ and ytterbium, Yb3+) core–shell nanoparticles (NPs), were fabricated by a one-step homogeneous precipitation process. Emission properties were studied by cathodo- and photoluminescence. Scanning electron and transmission electron microscopes were used to visualize and determine the size and shape of the NPs. Spherical NPs were obtained. Their core–shell structures were confirmed by x-ray diffraction and energy-dispersive x-ray spectroscopy measurements. We postulated that the molybdate rich core is formed due to high segregation coefficient of the Mo ion during the precipitation. The calcination process resulted in crystallization of δ/ξ (core/shell) NP doped Er and Yb ions, where δ—gadolinium molybdates and ξ—molybdates or gadolinium oxide. We confirmed two different upconversion mechanisms. In the presence of molybdenum ions, in the core of the NPs, Yb3+– (∣2F7/2, 3T2〉) dimers were formed. As a result of a two 980 nm photon absorption by the dimer, we observed enhanced green luminescence in the upconversion process. However, for the shell formed by the Gd2O3:Er, Yb NPs (without the Mo ions), the typical energy transfer upconversion takes place, which results in red luminescence. We demonstrated that the NPs were transported into cytosol of the HeLa and astrocytes cells by endocytosis. The core–shell NPs are sensitive sensors for the environment prevailing inside (shorter luminescence decay) and outside (longer luminescence decay) of the tested cells. The toxicity of the NPs was examined using MTT assay.

Use of luminescent gunshot residues markers in forensic context—Part II

Gunshot residues (GSR) are important physical evidence in firearm-related crimes. Recently developed non-toxic ammunition, however, requires a new methodology for its characterization. To overcome this drawback, the introduction of noncommercial luminescent markers in ammunition was proposed. These markers, synthesized and added to the gunpowder, presented as a versatile tool for GSR analysis, since they require UV radiation alone to visualize the luminescent GSR (LGSR). This has opened up new perspectives for understanding GSR behavior at a crime scene. This work aims to expand previous studies performed with the luminescent markers in forensic contexts, exploring four different important aspects related to GSR behavior. Using LGSR amount/dispersion and a series of blind tests with marked ammunition, we tried to (1) identify the shooter position; (2) estimate the shooting distance; (3) evaluate the influence of the pistol type on the LGSR distribution on the shooter’s hands and guns; and (4) study the transference of LGSR by a chain of handshaking. For this purpose, a portable UV lamp (λ=254nm) and/or techniques such as video spectral comparator (VSC) and scanning electron microscopy with energy dispersive X-ray analysis (SEM/EDS) were used to visualize and analyze the residues. As a result, the observation of the LGSR enabled accurate determination of the shooter position and the firing distance without any chemicals. Besides, the LGSR were visualized on different kinds of pistols, regardless of firing mechanism. And finally, this study evidenced transference of residues from shaking hands with the shooter, which should be carefully considered when interpreting the results of a GSR analysis.