Luminescence Method Research Articles

Direct Optical Research Methods in the Analytics of Phenol

The possibility of determining phenol in water by direct optical methods without the use of wet chemistry and concentration methods is considered. The bounds for determining the concentration of phenol in water from the absorption and luminescence spectra are estimated. As a reason limiting the use of the direct luminescent method for determining phenol, the influence of Raman effect of the solvent is considered, which becomes comparable with the luminescent signal even at phenol concentrations in water at a level of 10 μg/L, despite the fact that the sensitivity of the method is sufficient to determine concentrations that are 50 times less.

3,5-Dihydroxy Benzoic Acid-Capped CaF2:Tb3+ Nanocrystals as Luminescent Probes for the WO4 2- Ion in Aqueous Solution.

We report a facile and effective luminescence method for the determination of the WO42– ion in aqueous medium at initial pH = 6.3. This is achieved using 3,5-dihydroxybenzoic acid-capped CaF2:Tb3+ (5%) nanocrystals (NCs) as a luminescent probe. This is accomplished based on the energy transfer luminescence from the WO42– ion to the Tb3+ ion in small-size CaF2:Tb3+ NCs. Hydroxyl groups on the surface ligand helps in binding the tungstate ion to the surface of the NCs. With the gradual addition of the WO42– ion, the intensity of the Tb3+ excitation and emission spectra significantly increased. The linear range of the detection was from 1 to 10 μM for the WO42– ion (R2 = 0.99). The calculated detection limit was 0.4 μM (by applying the 3σ/K criterion).

Differential luminescent imaging method

Luminescent imaging is an area of active research for obtaining physical and chemical properties of a flow. Oxygen-sensitive luminescent probes are used as pressure-sensitive paints to capture unsteady flow over a fluid dynamic surface. The luminescent output is acquired by a photo-sensitive imaging chip, such as CCD and CMOS. Because these imaging chips acquire a digital signal, luminescent imaging is a poor technique for the measurement of small changes in the signal, which is equivalent to or lower than the noise level. A differential luminescent imaging method is studied to capture small fluctuations in a signal level. A theoretical model to describe the differential method is introduced and validated by experiments. Based on the static characterization, it is shown that the differential method possessed its sensitivity to capture fluctuations as small as 0.002% of the mean signal, which is an improvement in sensitivity by a factor of 81 as compared to the conventional luminescent imaging method.

Sensitive Label-Free Thermal Stability Assay for Protein Denaturation and Protein-Ligand Interaction Studies.

In modern biochemistry, protein stability and ligand interactions are of high interest. These properties are often studied with methods requiring labeled biomolecules, as the existing methods utilizing luminescent external probes suffer from low sensitivity. Currently available label-free technologies, e.g., thermal shift assays, circular dichroism, and differential scanning calorimetry, enable studies on protein unfolding and protein–ligand interactions (PLI). Unfortunately, the required micromolar protein concentration increases the costs and predisposes these methods for spontaneous protein aggregation. Here, we report a time-resolved luminescence method for protein unfolding and PLI detection with nanomolar sensitivity. The Protein-Probe method is based on highly luminescent europium chelate-conjugated probe, which is the key component in sensing the hydrophobic regions exposed to solution after protein unfolding. With the same Eu-probe, we also demonstrate ligand-interaction induced thermal stabilization with model proteins. The developed Protein-Probe method provides a sensitive approach overcoming the problems of the current label-free methodologies.

Assessment of Uranium Concentrations in Drinking Water Supply Sources Based on the Results of Laboratory Analysis of 238U and 234U Specific Activities and Laboratory Determination of Uranium According to GOST R 54499–2011

Introduction. The cause of toxicity and damaging effects of uranium and its compounds on the body lies in radioactivity of uranium isotopes and their decay products as well as their high chemical activity. In view of the above, we conducted parallel studies of specific activities and concentrations of uranium in household and drinking water supply sources. Materials and methods. We studied specific activities of uranium-234 and uranium-238 in the centralized drinking water supply sources of the Republic of Khakassia exceeding control levels in terms of specific total alpha activity (Aα) and converted them to mass concentrations of uranium. Parallel analyses of uranium concentrations in water using the luminescent method according to GOST R 54499–2011 were performed. Results. Our assessment of the radionuclide composition of centralized drinking water supply sources showed that Aα levels exceeding control levels were largely due to natural radionuclides uranium-238 (contribution up to 25%) and uranium-234 (contribution up to 69%). Based on the specific activities of uranium-234 and uranium-238, we estimated masses (concentrations) of uranium in water ranging from 0.007 to 0.06 mg/L depending on the water source. In the parallel tests of water samples according to GOST R 54499–2011, uranium concentrations ranged from 0.007 to 0.061 mg/L. Conclusions. The uranium concentrations in the republican centralized drinking water supply sources estimated on the basis of uranium-234 and uranium-238 specific activities differed from the concentrations of uranium measured by the luminescent method according to GOST R 54499–2011 within the error of the test method. In some settlements uranium concentrations in water exceeded the hygienic standard of 0.015 mg/L (GN 2.1.5.2280–07).

The Application of Spectral Luminescent Method to Examine Alcohol-Containing Liquids Produced Using Rectified Ethyl Alcohol

The possibility to apply the spectral-luminescent method using spectrophotometer Specord M40 with the attachment for fluorescence measuring to determine the nature of the basic alcohol in liquids produced using rectified ethyl alcohol has been considered. The analysis of model mixtures of aromatic amino acids (tryptophan, tyrosine, phenylalanine) has been performed to determine the characteristic bands in the luminescence excitation spectrum. The parameters of an adapted method for determining the nature of the basic alcohol (from food or non-food raw materials) of a liquid by comparative research of known spectrum of Lux ethyl rectified alcohol from food raw materials have been justified. The reasons limiting the application of the method have been analyzed: it is shown that the presence of food additives and flavors containing phenolic groups used in recipes of alcoholcontaining liquids can influence the luminescence of the basic alcohol significantly and, consequently, the identification result for the nature of the alcohol.

Detection of rhombo-ortho-tetra-cubic phase transitions on poled Er3+ and Sn4+ doped BaTiO3 ceramics by up-conversion luminescence

The three ferroelectric phase transitions rhombohedral-orthorhombic-tetragonal-cubic in 0.5 mol% Er doped BaSn0.06Ti0.94O3 ceramics are detected through up-conversion luminescence measurements. Noticeable changes are observed at the phase transition temperatures in the up-converted emission line intensity at 524 nm and the integrated intensity of the green emission band (514–537 nm) under 980 nm excitation. An electrically poled surface is found to be more sensitive, and the observed phase transition temperatures by the luminescence method are in agreement with the heat capacity and dielectric phase transition temperatures.

Serotonin-Containing Cells in the Primary Organ of Hemopoiesis after Autologous Bone Marrow Transplantation.

Serotonin-containing cytostructures of mouse bone marrow after autotransplantation were studied using Falk-Hillarp luminescent histochemical method, and expression of antiapoptotic marker was determined by the immunohistochemical reaction. Autotransplantation of the bone marrow in mice led to an increase in the number of mast cells; in 40 and 120 min after autotransplantation, serotonin content in mast cells increased by 12 and 23%, respectively, and in hemopoietic cells of the bone marrow - by 24 and 78%, respectively, which affected the early stages of proliferation and differentiation of hemopoietic cells. The mitotic index in bone marrow smears at these terms increased by 3.8 and 4.5 times. According to myelogram data, the fraction of early undifferentiated forms (lymphoblasts, erythroblasts) in the primary organ of hemopoiesis (bone marrow) increased.

An inexpensive and sensitive turn-on luminescence protocol for sensing formaldehyde

Formaldehyde (FA), the simplest and most widely-used aldehyde, can pose serious health issues when present at elevated concentrations. Here, we report a "turn-on" terbium photoluminescence method for the efficient detection of FA. A pro-sensitizer molecule was designed and synthesised, which releases the sensitizer in the presence of FA inside the terbium cholate hydrogel matrix, resulting in a "turn-on" luminescence response. The introduction of a paper-based sensing approach makes the protocol simpler and cost-effective, and has a detection limit as low as 100 nM.

Luminescence-based early detection of fatigue cracks

Classic non-destructive fatigue crack detection methods reveal the state of the fatigue damage evolution at the moment of application, generally not under operational conditions. The here introduced crack luminescence method realizes a clear visibility of the occurred and growing crack in loaded components during operation. Different established experiments show that due to the sensitive coating a crack formation can be detected even in early stage under the premise the crack reached the surface. The coating consists of two layers with different properties and functions. The bottom layer emits light as fluorescence under UV radiation. The top layer covers the fluorescing one and prevents the emitting of light in case of no damage at the surface. In case of surface crack occurrence, the luminescent light is clearly noticeable by visual observations and also by standard camera equipment which makes automated crack detection possible as well. It is expected that crack luminescence can increase structural safety as well as reduce costs and time for inspections and preventive maintenance.

Temperature-Independent Lifetime and Thermometer Operated in a Biological Window of Upconverting NaErF4 Nanocrystals.

Lifetime of lanthanide luminescence basically decreases with increasing the ambient temperature. In this work, we developed NaErF4 core–shell nanocrystals with compensation of the lifetime variation with temperature. Upconversion lifetime of various emissions remains substantially unchanged as increasing the ambient temperature, upon 980/1530 nm excitation. The concentrated dopants, leading to extremely strong interactions between them, are responsible for the unique temperature-independent lifetime. Besides, upconversion mechanisms of NaErF4 core-only and core–shell nanocrystals under 980 and 1530 nm excitations were comparatively investigated. On the basis of luminescent ratiometric method, we demonstrated the optical thermometry using non-thermally coupled 4F9/2 and 4I9/2 emissions upon 1530 nm excitation, favoring the temperature monitoring in vivo due to both excitation and emissions fall in the biological window. The formed NaErF4 core–shell nanocrystals with ultra-small particle size, highly efficient upconversion luminescence, unique temperature-independent lifetimes, and thermometry operated in a biological window, are versatile in applications such as anti-counterfeiting, time-domain manipulation, and biological thermal probes.

Visual Detection of Fluoride Anions Using Mixed Lanthanide Metal-Organic Frameworks with a Smartphone.

Fluoride ion (F-) is one of the most harmful elements in drinking water. Over-intake of F- can result in dental fluorosis, kidney failure, or DNA damage. Therefore, developing affordable, equipment-free, and reliable methods for F- detection is an important goal. In this work, a series of mixed lanthanide metal-organic frameworks were synthesized using a triazine-based planar ligand, 4,4',4″-s-triazine-2,4,6-triyltribenzoate (TATB) and mixed lanthanide ions (Tb3+ and Eu3+). The luminescent color of the Tb/Eu(TATB) can be finely modulated by changing the Tb3+/Eu3+ ratio in the synthesis procedure. Benefiting from the unique host-guest interaction (e.g., Lewis acid-base interaction), between F- and MOF host, a highly selective, sensitive, and reliable fluoride sensor was then developed. Moreover, visual detection of F- was achieved with a smartphone by identifying the RGB value. Drinking water samples were analyzed for F-, and the results obtained by our ratiometric luminescent method were consistent with those by ion chromatographic strategy. This easy-to-use sensor provides reliable detection of F- in everyday applications for nonexpert users, especially in remote rural areas.

A luminescent method for detection of parathion based on zinc incorporated metal-organic framework

A highly sensitive method for parathion detection based on a luminescent zinc incorporated metal-organic framework (Zn-MOF) is reported in this work. The Zn-MOF was synthesized under solvothermal conditions with tetrakis (4-carboxyphenyl) porphyrin (TCPP) and 1,2,4,5-tetrakis (4-carboxyphenyl) benzene (H4TCPB) providing the ligand. The as-prepared Zn-MOF emitted violet fluorescence under ultraviolet light. By quenching the fluorescence intensity, the Zn-MOF showed selective response to parathion among 15 kinds of organophosphates (OPPs), with minimum response concentration 1.950 μg•L−1. The Zn-MOF based fluorescent method was used for parathion spiked irrigation water and a satisfactory recovery rate was obtained, indicating its potential for rapid analysis of environmental samples.

Flow visualization and transient behavior analysis of luminescent mini-tufts after a backward-facing step

Luminescent mini-tufts method has been used for surface flow visualization for a long time. One major challenging point of this method is quantitative analysis of transient flows and the dynamic structures. This study is focused on the application of luminescent mini-tufts method in transient flows. A backward-facing step (BFS) is used in this analysis, which is one classic model that consists both flow separation and re-attachment processes. In this study, the instantaneous mini-tufts recognition, image averaging and tuft inclination angle/tuft angle estimation processes are introduced for the analysis of luminescent mini-tufts for the first time on backward-facing step flow (Rem = 2.0 × 105–7.9 × 105 and Reh = 1.3 × 104–5.3 × 104). Detailed transient features and characterization process for the backward-facing step model are explained in this study. The combination of optical-oil flow and hot-wire anemometry methods with luminescent mini-tufts are also shown useful to give comprehensive flow field information, including the surface flow behaviors, boundary layer, re-attachment position identification, etc. In addition, the decomposition of the luminescent mini-tufts visualization data is also conducted to give the power spectral density (PSD) and characteristic frequencies for the mini-tufts behaviors under transient fluctuating flow conditions.

2136. Rapid Antimicrobial Susceptibility Testing using ATP Luminescence and Machine Learning Methods

BackgroundTo prevent the spread of drug-resistant bacteria, a rapid and accurate antimicrobial susceptibility test (AST) is necessary. Recently, morphokinetic microscopy approaches have been reported as a rapid AST method. However, these still require several hours to obtain a minimum inhibitory concentration (MIC). Adenosine triphosphate (ATP) luminescence has also been reported as a rapid AST method that can detect bacterial growth more rapidly than morphokinetic approaches, since ATP in bacteria increases prior to bacterial division. In this study, we designed a new machine learning-based algorithm that predicts MIC rapidly, using a dataset that contains ATP luminescence patterns and conventional MICs determined by turbidity. Essential agreement (EA) rates between rapid and conventional MIC were then evaluated.MethodsSixty-three strains of E. coli (ATCC 25922 and clinical isolates from Toyama University Hospital) were tested. Bacterial suspensions were diluted 500-fold in Mueller–Hinton broth from 0.5 McF solutions, and the final concentration of bacteria was 3×105 CFU/mL. The suspensions were dispensed into a 96-well microplate, which had 12 antimicrobials in two-fold dilution series, and the microplate was incubated at 35°C. At each measurement time point, the amount of ATP in a 10 μL aliquot from each well was evaluated by our original measurement system, which can sensitively detect ATP luminescence equivalent to a single bacterium. After 22 hours, MIC was determined conventionally by measuring turbidity. A rapid MIC for each bacterium was estimated by the algorithm based on the dataset consisting of the rest of the 62 strains (leave-one-out cross validation).ResultsTable 1 shows the EA rate for the 12 antimicrobials; EA rates > 90% were achieved for 7 antimicrobials in 2 hours and for 12 antimicrobials in 3 hours. In 6 hours, an average EA rate > 97% was achieved.ConclusionUsing the dataset, our new machine learning-based algorithm predicted MIC rapidly within 2 hours with an EA rate > 90% for 7 antimicrobials. The rapid AST detected by the ATP luminescence method will contribute toward both appropriate antimicrobial treatment and reduction in medication and admission charges. In the future, other species of bacteria will be evaluated by our ATP method. Disclosures All authors: No reported disclosures.

Assessment of Virgin Olive Oil Adulteration by a Rapid Luminescent Method.

The adulteration of virgin olive oil with hazelnut oil is a common fraud in the food industry, which makes mandatory the development of accurate methods to guarantee the authenticity and traceability of virgin olive oil. In this work, we demonstrate the potential of a rapid luminescent method to characterize edible oils and to detect adulterations among them. A regression model based on five luminescent frequencies related to minor oil components was designed and validated, providing excellent performance for the detection of virgin olive oil adulteration.

Luminescent control of polycyclic aromatic hydrocarbons content in water systems

To control the content of polycyclic aromatic hydrocarbons in aqueous media and to ensure effective sewage treatment of natural contaminated waters, a luminescent solid-substrate method was applied. This method permits combining the preceding sorption concentration of substances on a cellulose matrix, modified with a surfactant, and analyzing directly in the solid phase of the sorbent. Optimal characteristics of luminescent control of ecotoxicant content before and after water purification were determined

Statistical luminescence method for determining the region of origin of emeralds

Large samples of emeralds from eight deposits in Brazil, China, Zambia, Russia, Afghanistan, Colombia, and Tanzania were studied using pulsed cathodoluminescence to develop a nondestructive method for determining their region of origin. The average wavelength, variance, and inverse effective width of the luminescence band in the 660–870 nm wavelength range of these minerals followed normal distributions with intensities characteristic of each of the regions of origin. Based on this result, a statistical luminescence method for determining the region of origin of the minerals was proposed and tested. This method uniquely determined the region of origin for more than 80% of the emeralds.

Clinical Value of Serum Cancer Antigen 19-9 as a Tumor Screening Marker among Healthy Individuals

Background: Serum tumor markers are convenient, non-invasive, acceptable to patients and play an important role as an ancillary tumor diagnostic tool. CA 19-9 has become a common tumor marker, specific for digestive system tumors. The study was carried out to determine the value of CA 19-9 as a tumor screening marker among healthy individuals.
 Materials and Methods: This study had been carried in Dhaka Medical college Hospital from January 2016 to January 2018. The serum CA 19-9 level was detected using a microsome luminescence method. Individuals with high CA 19-9 levels underwent further examination, including routine fecal testing, thoracic and abdominal computed tomography (CT) scan, gastroscopy, and colonoscopy. These individuals had regular follow-up examinations.
 Results: Over a 3-year period, the serum CA19-9 levels of 960 healthy individuals were estimated. The CA 19-9 level of 15 individuals was positive (positive rate: 1.56%), including 7 men (7/699; 1.001%) and 8 women (8/261; 3.06%). There was a significant difference between males and females (p<0.01), The overall tumor detection rate was 0.72% (7/960) including 6/699 men (0.85%) and 1/261 women (0.38%).
 Conclusion: Therefore, elevated CA 19-9 level can be used to assist in the diagnosis malignancy.
 J MEDICINE JUL 2019; 20 (2) : 92-94

Luminescence dating of buried cobble surfaces from sandy beach ridges: a case study from Denmark

Here we investigate the use of optically stimulated luminescence (OSL) for dating cobbles from the body of successive beach ridges and compare cobble surface‐derived ages to standard quartz OSL ages from sand. Between four and eight cobbles and sand samples (age control) were dated with the luminescence method, taken from the modern beach and from beach ridges on the south and north extremes of a prograding spit on the westernmost coast of Lolland, Denmark. Luminescence‐depth profiles perpendicular to the surfaces of the cobbles show that the feldspar infrared signals stimulated at 50 °C were fully reset to various depths into the cobbles prior to final deposition; as a result, the equivalent doses determined from close to the surface of such cobbles can be used to calculate burial ages. Beach‐ridge burial ages given by the average of ages of individual cobbles taken from the same site are consistent, within errors, with the ages derived from the sand samples. Cobble‐ and sand‐derived ages show that the southernmost beach ridge at Albuen was formed around 2 ka ago, indicating that this sandy spit is younger than other coastal systems in Denmark. The agreement between ages derived from clasts and from standard quartz OSL in this study confirms that, even in the absence of sandy sediments, we can reliably date sites using OSL by targeting larger clasts. In addition, the record of prior light exposure contained in the shape of the cobbles’ luminescence‐depth profile removes one of the major uncertainties (i.e. the degree of signal reset prior to burial) in the luminescence dating of high latitude sites.