From the cellular to tissue alterations induced by two rare earth elements in the mussel species Mytilus galloprovincialis: Comparison between exposure and recovery periods

The global effort to achieve carbon neutrality has led to an increased demand for renewable energy technologies and their raw materials, namely rare earth elements (REEs). These elements possess unique properties and are used in various applications. However, the increased use of REE-based technologies has resulted in higher amounts of electronic waste, leading to elevated REEs concentrations found in the aquatic environment, with poorly understood threats to wildlife. Praseodymium (Pr) and europium (Eu) are two REEs that, despite their potential environmental risks, have almost unknown effects on aquatic organisms. Therefore, the present study aimed to assess the impacts of different concentrations of Pr and Eu (0, 10, 20, 40, and 80 μg/L) in the mussel species Mytilus galloprovincialis, as well as their ability to recover from exposure to the highest concentration. Mussels accumulated both elements in a dose-dependent manner, with the accumulation of Pr being higher. Accompanying the increase of metabolism, mussels exposed to Pr not only enhanced the activity of the antioxidant enzymes superoxide dismutase (up to 40 μg/L) and glutathione reductase (at 80 μg/L) but also the activity of the biotransformation enzymes carboxylesterases (CbE's) and glutathione S-transferases (GSTs) (at 80 μg/L). Nevertheless, these defence mechanisms were not sufficient to prevent cellular damage. All the Eu concentrations induced cellular damage, despite an increase in the activity of biotransformation enzymes (CbE's and GSTs) in mussel tissue. According to the histopathology assessment, mussels were not able to recover after exposure to both elements and lower concentrations induced higher injuries in digestive tubules. This study highlights that exposure to Pr and Eu had adverse effects on M. galloprovincialis, even at the lowest tested concentration, which may eventually impact mussels' growth, reproductive capacity, and survival.

Complexation and extraction of trivalent actinides over lanthanides using highly soluble phenanthroline diamide ligands with different side chains

Although phenanthroline diamide ligands have been widely reported, their limited solubility in organic solvents and poor performance in the separation of trivalent actinides (An(III)) and lanthanides (Ln(III)) at high acidity are still clear demerits. In this study, we designed and synthesized three highly soluble phenanthroline diamide ligands with different side chains. By introducing alkyl chains and ester groups, the ligands solubility in 3-nitrotrifluorotoluene is increased to over 600 mmol/L, significantly higher than the previous reported phenanthroline diamide ligands. Based on anomalous aryl strengthening, benzene ring was incorporated to enhance ligand selectivity toward Am(III). Extraction experiments demonstrated favorable selectivity of all the three ligands towards Am(III). The optimal separation factor (SFAm/Eu) reaches 53 at 4 mol/L HNO3, representing one of the most effective separation of An(III) over Ln(III) under high acidity. Slope analysis, single crystal structure analysis, as well as titration of ultraviolet visible spectroscopy, mass spectrometry, and nuclear magnetic resonanc confirmed the formation of 1:1 and 1:2 complex species between the metal ions and the ligands depending on the molar ratio of metal ions in the reaction mixture. The findings of this study offer valuable insights for developing phenanthroline diamide ligands for An(III)/Ln(III) separation.

Particulate matter from water moss of a large Siberian river: Morphometric, mineral, elemental and radionuclide composition

Particulate matter trapped by tufts of water moss Fontinalis antipyretica inhabiting fast flowing waters of the Yenisei River (Siberia, Russia) contaminated with artificial radionuclides has been studied as a potential monitor of radioactive releases to the river. Particulate matter, which was removed from wet tufts of water moss of the Yenisei by rinsing them in water, constituted at least 38% of bulk dry weight of the moss biomass sample and was similar in the contents of chemical elements, minerals, organic matter, and artificial radionuclides to bottom sediments of the Yenisei. Considerable bulk percentages of artificial radionuclides in the sample of water moss, 77% of 137Cs, 44% of 60Co, 41% of 152Eu, 55% of 154Eu, 66% of 241Am, and 34-36% of plutonium were associated with extracellular particles. The comparative study and correlation analysis suggested that 137Cs was mainly associated with mineral particles trapped by moss and that organic matter was responsible for binding plutonium in samples of water moss. Consequently, analysis of extracellular particles of water moss can provide data on contents and speciation of radionuclides transported by water current. Although a considerably high proportion of particulate matter had been washed out from tufts of water moss, some extracellular mineral particulate material and a large number of epiphytic diatoms remained attached to leaves of water moss. Our study proves that particulate matter trapped by water moss can be used as an informative monitor to trace radioactive pollutants transported by water current in running waters deficient in bottom sediments and potential biomonitors.

Kinetic analysis of mass transfer of Eu(III) in extractant-impregnated polymer-layered silica particle in multiple-ion distribution system

The Eu(III) distribution mechanism in single extractant-impregnated polymer-layered silica particle in a complex solution containing multiple lanthanide ions was investigated using fluorescence microspectroscopy, which was compared with the single-ion distribution system. The rate-determining step of the Eu(III) distribution was the reaction of Eu(III) with the two extractant molecules in the particle. The distribution mechanism and rate constants obtained in the multiple lanthanide ions-distribution system agreed with those of the single-ion distribution system.

Chitosan-minerals-based composites for adsorption of caesium, cobalt and europium

Currently, there is a growing interest in the use of natural materials in various fields of science, technology and environmental protection due to their availability, low-cost, non-toxicity and biodegradability. Chitosan, natural clay of local origin, montmorillonite, zeolite, cross-linking agents (epichlorohydrin, sodium tripolyphosphate, glutaraldehyde) and plasticisers (glycerol) were used to synthesise composites. The composites were characterised by attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR), X-ray diffraction analysis (XRD) and scanning electron microscope (SEM), tested for their antibacterial activity and used in batch experiments to study the adsorption of caesium, cobalt and europium ions. The maximum capacities for adsorption of caesium, cobalt and europium on the composites were 1400 mg/g, 900 mg/g and 18 mg/g, respectively. The experimental data fit better the Langmuir isotherm model and indicate favourable monolayer adsorption of Cs+, Co2+ and Eu3+ at homogeneous sites of the composites. The experimental data were in better agreement with the pseudo-second-order non-linear kinetic model for most elements and adsorbents. Adaptive neuro-fuzzy inference system proved to be a practical tool with good performance and generalisation capability for predicting the adsorption capacity of composites for caesium, cobalt, and europium ions. It was found that the predicted data were very close to the experimental data.

Europium-doped cerium oxide nanoparticles: investigating oxygen vacancies and their role in enhanced photocatalytic and magnetic properties

In this study, pure and europium-doped (2%, 4%, 6%, and 8%) cerium oxide (CeO2) nanoparticles (NPs) were employed for efficient dye removal through photocatalytic approach. XRD and TEM confirmed the formation of pure CeO2 nanoparticles, while XPS and Raman spectroscopy were used to analyze the electronic properties and lattice defects, such as oxygen vacancies. The presence of lattice defects, which increased with the concentration of Eu, was found to be responsible for the enhanced degradation of Rose Bengal dye (82.4% for 8% Eu-doped sample) in 75 min. FTIR confirmed the chemical composition of the synthesized sample. The band at 617 cm-1, corresponding to the symmetrical stretching vibration mode of (Ce-O-Ce) or (Ce-O-Eu). The magnetic properties of synthesized samples were examined using VSM, revealing an increase from 4.48 to 11.0 emu/g in magnetization. This enhancement was attributed to F-center exchange mechanism (FCE), resulting from the presence of oxygen vacancies. These findings contribute to the development of advanced materials for sustainable wastewater treatment and spintronics.

A comprehensive study for the potential removal of 152+154Eu radionuclides using a promising modified strontium-based MOF

A facile modification of a strontium-based MOF using oxalic acid was carried out to prepare MTSr-OX MOF, which was used as a potential substance for eliminating 152+154Eu radioisotopes. Various analytical techniques were used to characterize MTSr-OX-MOF. The prepared MOF had a rod-like structure with a BET surface area of 101.55 m2 g-1. Batch sorption experiments were used to investigate the sorption performance of MTSr-OX-MOF towards 152+154Eu radionuclides where different parameters like pH, contact time, initial 152+154Eu concentration, ionic strength, and temperature were scrutinized to determine the optimum conditions for 152+154Eu removal. MTSr-OX-MOF showed superior effectiveness in the elimination of 152+154Eu with a maximum sorption capacity of 234.72 mg g-1 at pH 3.5. Kinetics fitted with the pseudo-second-order model and the Langmuir model correctly described the sorption mechanism. The thermodynamic variables were carefully examined, demonstrating that the 152+154Eu sorption was endothermic as well as spontaneous. The MTSr-OX-MOF has been found to be a significantly more effective sorbent towards 152+154Eu than that of many other adsorbents. When applied to real active waste, MTSr-OX-MOF demonstrated excellent removal performance for a wide range of radionuclides. As a result, the MTSr-OX-MOF can be recognized as an attractive solution for the 152+154Eu purification from active waste.

Long-term toxicity of chlorpromazine, diclofenac and two lanthanides on three generations of Ceriodaphnia dubia

Amultigenerational study on Ceriodaphnia dubia was carried out by exposing three subsequent generations to pharmaceuticals chlorpromazine (CPZ) and diclofenac (DCF), and two lanthanide chlorides, gadolinium as GdCl3 and europium as EuCl3. As the treatments, environmentally relevant concentrations were chosen (0.001, 0.01 and 0.1 mg/L for CPZ; 0.1, 1 and 10 mg/L for DCF; 0.425, 4.25 and 42.5 µg/L for Gd and 0.41, 4.1 and 41 µg/L for Eu). Survival, population growth and reproduction success were evaluated at 21 and 30 days of exposure, and the whole observation period lasted 40 days. The least sensitive to all selected substances was the first daphnid generation (F1). Within 21-day exposure, no significant effects of the psychotropic drug CPZ on C. dubia survival were observed in generations F1-F3. The anti-inflammatory drug DCF did not affect survival in the F1 generation; however, it significantly reduced survival in the F3 generation at 1-10 mg/L. Both lanthanides did not affect survival in the F1 and F2 generations of C. dubia but considerably decreased survival in the F3 at 4-42 µg/L. Both pharmaceuticals stimulated the reproduction of C. dubia in the F1 generation, while inhibition occurred at the highest tested concentrations in generations F2 and F3. The inhibitory effect on the reproductive success of lanthanides in the F2 generation resembled that for CPZ but not for DCF. The dynamics of adverse effects during the 21-30-day period revealed that despite increased mortality in the controls (up to 30%), concentrations used in the study minified, in most instances, the survival and aggravated population growth and reproduction success of C. dubia. Our data suggest that C. dubia as a test organism can be used for 21 days in multigenerational investigations, especially when testing close to environmental concentrations. In this respect, the standard C. dubia chronic toxicity assay seems limited since prolonged observations and several generations of daphnids are required to obtain reliable information for the risk assessment of potentially aggressive chemicals.

Eu(III) transfer in single N,N,N',N'-tetraoctyldiglycolamide-impregnated polymer-coated silica particle using fluorescence microspectroscopy: transfer mechanism and effect of polymer crosslinking degree

A microcapillary manipulation system combined with fluorescence microspectroscopy enabled us to analyze mass transfer in a single particle. In this study, we revealed the Eu(III) distribution in a single diglycolamide-derivative extractant (TODGA)-impregnated polymer-coated silica particle. The reaction of Eu(III) with two TODGA molecules in the polymer layer was the rate-limiting process, which was revealed by the relationship between the rate constants (k1 and k-1) and concentrations of Eu(III) and HNO3. The decrease in the crosslinking degree of the polymer layer caused an increase in only k-1. This indicates that hydrophilic environments at lower crosslinking degrees enhance the stability of the charged Eu(III) species such as Eu3+, Eu(NO3)2+, and Eu(NO3)2+.

Biocompatible, Europium-Doped Fluorapatite Nanoparticles as a Wide-Range pH Sensor

The development of a simple, biocompatible, pH sensor with a wide range of detection, using a single fluorescent probe is highly important in the medical field for the early detection of diseases related to the pH change of tissues and body fluids. For this purpose, europium-doped fluorapatite (FAP: Eu) nanoparticles were synthesized using the coprecipitation method. Doping with the rare earth element europium (Eu) makes the non-luminescent phosphate mineral fluorapatite, luminescent. The luminous response of the sample upon dissolution in hydrochloric acid (HCl), in highly acidic to weakly basic media, makes it a potential pH sensor. A linear variation was observed with an increase in pH, in both the total intensity of emission and the R-value or the asymmetry ratio. The ratiometric pH sensing enabled by the variation in R-value makes the sensor independent of external factors. The structural, optical, and photoluminescent (PL) lifetime analysis suggests a particle size-dependent pH sensing mechanism with the changes in the coordinated water molecules around the Eu3+ ion in the nanoparticle. Given its exceptional biocompatibility and pH-dependent fluorescence intensity for a wide range of pH from 0.83 to 8.97, the probe can be used as a potential candidate for pH sensing of biological fluid.

Diblock versus block-random copolymer architecture effect on physical properties of Gd3+-based hybrid polyionic complexes

HYPOTHESIS

Random insertion of vinylphosphonic acid (VPA) units into a of PEG-PAA block copolymer improves the chemical stability and properties of hybrid nanoobjects obtained from the complexation of the copolymer with metal ions.

EXPERIMENTS

Block polymers based on poly(acrylic acid) (PAA) and poly(ethylene glycol) (PEG) are modified by random insertion of 0 to 100 % of phosphonic acid functions in PAA block by a RAFT polymerization process. These polymers are then used to form hybrid polyionic complexes (HPICs) by complexation with gadolinium or europium ions. The properties of the obtained assemblies are evaluated by magnetic relaxivity, fluorescence and light scattering measurements.

FINDINGS

The insertion of VPA units within the PAA block increases the chemical stability of the hybrid micelles by maintaining their integrity even at low pH. This insertion also minimizes the exchange of ions between HPICs and the surrounding medium thanks to a strengthening of interactions toward lanthanide ions. When such systems are used as MRI contrast agents or luminescent probe, 50/50 AA/VPA composition appears to be a good compromise to achieve optimal relaxivity or luminescent properties while ensuring a good chemical stability.

Pushing the boundary of covalency in lanthanoid-tellurium bonds: Insights from synthesis, molecular and electronic structures of low-coordinate, monomeric europium(II) and ytterbium(II) tellurolates

Owing to the strict hard/soft dichotomy between the lanthanoids and tellurium atoms, and the strong affinity of lanthanoid ions for high coordination numbers, low-coordinate, monomeric lanthanoid tellurolate complexes have remained elusive as compared to the lanthanoid complexes with lighter group 16 elements (O, S, and Se). This makes the development of suitable ligand systems for low-coordinate, monomeric lanthanoid tellurolate complexes an appealing endeavor. In a first report, a series of low-coordinate, monomeric lanthanoid (Yb, Eu) tellurolate complexes were synthesized by utilizing the secondary bonding interaction stabilized hybrid organotellurolate ligands. The reaction of bis[2-((dimethylamino)methyl)phenyl] ditelluride, 1 and 8,8'-diquinolinyl ditelluride, 2 with Ln0 metal (Ln = Eu, Yb) resulted in the formation of monomeric complexes [LnII(TeR)2(Solv)2] [R = C6H4(CH2NMe2)-2] [3: Ln = Eu, Solv = tetrahydrofuran; 4: Ln = Eu, Solv = acetonitrile; 5: Ln = Yb, Solv = tetrahydrofuran; 6: Ln = Yb, Solv = pyridine] and [EuII(TeNC9H6)2(Solv)n] (7: Solv = tetrahydrofuran, n = 3; 8: Solv = 1,2-dimethoxyethane, n = 2), respectively. Complexes 3-4 and 7-8 represent the first sets of examples of monomeric europium tellurolate complexes. The molecular structures of complexes 3-8 are validated by single-crystal X-ray diffraction studies.

Designing and Judd-Ofelt evaluation of versatile luminescent Eu (III) complexes sensitized with β-diketone ligand for multifarious applications

The present research work entails synthesis of one binary and four ternary red light emitting Eu (III) based complexes with 3-benzylidene-2,4-pentanedione as main ligand and 1,10-phenanthroline, bathophenanthroline, neocuproine and 4,4'-dimethyl-2,2'-bipyridyl as auxiliary ligands. The Metal-Organic framework of the series was elucidated using EDAX, elemental analysis, FT-IR and ¹ H-NMR. This Eu (III) series exhibit optimum thermal stability making them a promising candidate for OLED's. On the basis of emission spectra their optical parameters such as non-radiative and radiative decay rate, luminescence decay time, intrinsic quantum efficiency and Judd-Ofelt intensity parameter were determined. The mono-centric luminescence and Judd-Ofelt parameters reveals the non-existence of symmetry around the europium center. CIE chromaticity coordinates, CCT values, color purity and asymmetric ratios authenticate the color coordinates of complexes in red region. Optical band gap values lies within wide band gap semiconductors range revealing their utilization in military radars, biological labeling.

Dual-responsive ratiometric fluorescent sensor for tetracyclines detection based on europium-decorated copper nanoclusters

Development of accurate and efficient TCs residue analysis methods is of great significance for the protection of environment, food safety and public health. Herein, a dual-responsive ratiometric fluorescence sensor being capable of simple and sensitive detection of tetracycline (TC) was presented, which was constructed by immobilizing europium ions (Eu³⁺) onto the mercaptopropionic acid stabilized copper nanoclusters (MPA-Cu NCs). In the presence of TC, the red fluorescence of Eu³⁺ was enhanced through antenna effect (AE), while the green fluorescence of MPA-Cu NCs was quenched through internal filter effect (IFE), leading to an obvious fluorescence color evolution from green to red for the probe solution. In addition to successful design of a smartphone-assisted colorimetric analysis platform for portable detection, a logic gate device capable of intelligently monitoring TC concentration is also designed.

The biological functions of europium-containing biomaterials: A systematic review

The biological functions of rare-earth elements (REEs) have become a focus of intense research. Recent studies have demonstrated that ion doping or alloying of some REEs can optimize the properties of traditional biomaterials. Europium (Eu), which is an REE with low toxicity and good biocompatibility, has promising applications in biomedicine. This article systematically reviews the osteogenic, angiogenic, neuritogenic, antibacterial, and anti-tumor properties of Eu-containing biomaterials, thereby paving the way for biomedical applications of Eu. Data collection for this review was completed in October 2022, and 30 relevant articles were finally included. Most articles indicated that doping of Eu ions or Eu-compound nanoparticles in biomaterials can improve their osteogenic, angiogenic, neuritogenic, antibacterial, and anti-tumor properties. The angiogenic, antibacterial, and potential neuritogenic effects of Eu(OH)₃ nanoparticles have also been demonstrated.

Sorption and transport characteristics of europium on sandy soils

Radioactive europium can be released as a fission product during nuclear incidents and pose a threat to the human and surrounding environment because of its biological activity and long decay half-lives. For safe design issues and human health protection demands in construction of the planned nuclear power plants (NPPs) at Al-Dabaa site, it is necessary to study the sorption and transport of different radionuclides as europium within the selected area for predicting their fate at any crisis. Many soil samples were collected from different locations at the area selected along the northwestern coast of Egypt. The samples were transported to the laboratory, preserved, and characterized using X-Ray fluorescence (XRF), Fourier transform infrared spectroscopy (FT-IR), and X-Ray diffraction (XRD). Experiments were performed to study the sorption and transport kinetics of Eu(III) ions on two sandy soil samples from the collected ones. The effect of different parameters (e.g. contact time, pH, initial europium concentration, and temperature) on the sorption behavior europium was explored in a static condition. The maximum sorption capacity was determined and found to be 3.4 and 7.0 mg g^-1 for sorption of Eu(III) ions onto soil-1 and soil-2, respectively. Different models were applied to assess the sorption of europium onto the surface of the investigated soils. Data confirmed that Eu retention was attained through a chemisorption process. Further, the thermodynamic parameters were determined and their values confirmed the endothermic nature of the sorption process. The transport of europium radionuclides, with groundwater, through homogeneous porous media with uniform one-dimensional flow in the geosphere was processed and the relative migration velocity was determined in presence of both distilled and seawater media. The transport of Eu(III) radionuclides was higher in presence of seawater than that in presence of distilled water by about two order of magnitude. This obviously clarified the effect of seawater in accelerating the transport of radionuclides with groundwater in the geosphere of studied area. The role of different competing ions have various valances on the relative migration velocity was explored. Further, the time required for studied radionuclides to reach Mediterranean Sea was determined.

Modified lanthanide-doped carbon dots as a novel nanochemosensor for efficient detection of water in toluene and its potential application in lubricant base oils

A fast and efficient method was developed for obtaining europium(III)-doped surface-modified carbon dots with a hydrophobic coating. This surface functionalization improved the dispersibility of the nanoparticles in non-polar media, as well as modified the accessibility of water molecules to the europium ions. These two features allowed studying the application of doped carbon dots as moisture nanochemosensor, demonstrating high stability over time of both the photoluminescent signal intensity and the stability of the dispersions. The developed nanochemosensor was used to determine water in toluene with a detection limit of 8.5 × 10^-4 M and a quantification limit of 2.4 × 10^-3 M. The proposed system matches and even improves other methodologies for water determination in organic solvents; it has a low detection limit and a fast response time (almost instantaneous) and requires neither expensive material nor trained personnel. The results suggest a promising future for the development of a new sensing phase for moisture determination in lubricant base oil.

Liposome Biodistribution via Europium Complexes

Vector biodistribution is a requirement prior pharmaceutical development. Radioactive tracers allow the most sensitive and quantitative assessment of biodistribution, and conventional fluorophores are widely used in academic laboratories. We propose here to use europium complexes as a label for nanoparticles or biotherapeutics taking liposomes as models. Time-resolved fluorimetry (TRF) has the tremendous advantage of taking into accounts the fluorescence decay time of the lanthanide chelates, resulting in an improved sensitivity in biological media. The work described aimed following liposome biodistribution by TRF. An octadecyl-DTPA.Eu compound has been prepared and incorporated into liposomes without altering its fluorescence signal. The method has been validated through a comparison with fluorophore-labeled liposomes. The way to proceed when using this method for liposome biodistribution assessment is detailed. It could obviously be applied to other nanosystems, such as lipid nanoparticles.

Determination of metanil yellow dye in turmeric powder using a unique fluorescence Europium doped carbon dots

Turmeric, a spice known for its therapeutic benefits, is a major source of curcumin which is a polyphenol with anti-inflammatory properties. It aids in treating arthritis, anxiety, metabolic syndrome, liver disease, hyperlipidemia, and inflammatory diseases. In this study, a novel fluorescence probe was designed to detect the adulteration of curcumin by metanil yellow (a harmful artificial dye). The probe was synthesized from the carbonization and conversion of the Tannic acid-Eu³⁺ complex to bright fluorescence Eu-carbon dots in the presence of orthophosphoric acid. The size, morphological, and optical features of the formed Eu-carbon dots were characterized by UV, SEM, TEM, and FTIR techniques. Furthermore, the formed Eu-carbon dots possess unique fluorescence excitation and emission features at 307.5 nm and 340.6 nm, respectively. These fluorescence features can be successfully quenched upon the addition of metanil yellow dye. The value of quenching in the fluorescence intensity of the Eu-C-dots was directly proportional to the dye's concentration. The LOD value for the proposed method was 0.390 µg/mL with a linear range of 1.0-15.0 µg/mL. Furthermore, the methodology exhibited good recovery values for determining the studied dye without any interference from the presence of curcumin.

Decontamination of neutron-activated radioactive concrete waste by separating Eu, Co, Fe, and Mn-containing sand particles using dense medium separation

Neutron-activated concrete waste is one of the most challenging radioactive wastes to decontaminate because the radionuclides exist in a chemically stable binding state, and it is very difficult to break those bindings with the conventional acid decontamination method. Here, we suggest a new dense medium separation (DMS) of felsic and mafic minerals from simulated neutron-activated concrete waste using sodium-polytungstate (SPT) solution because most elements (Eu, Co, Fe, and Mn) that can be activated by neutrons are concentrated in mafic minerals. We also determined the optimal density of the SPT solution as ∼ 2.70 g/cm³, and a high degree of decontamination was achieved for sand particles ranging from 75 to 500 µm in size. Under these optimized conditions, DMS (80.02%) exhibits much higher radionuclide removal efficiency (RRE) than 5 M acid decontaminations (23.27-31.29%) for Eu. Furthermore, DMS (59.38-63.36%) shows similar RRE to 5 M acid decontaminations (41.67-73.94%) for Fe, Mn, and Co. We believe this DMS process could be useful and applicable to the decontamination of neutron-activated concrete wastes because it is possible to perform a large-scale process compared to conventional acid decontamination methods, which is also advantageous in reducing secondary waste generation and facile radionuclide recovery.

Radiolysis effect on Eu(III)-superplasticiser interactions in artificial cement and squeezed cement pore waters

In the framework of the French deep geological repository for radioactive waste, cement-based materials are envisaged to immobilize radionuclides and/or provide protection from radiation to the environment. Superplasticisers (SPs) are added to these materials to increase their workability. SPs will undergo degradation by coupled radiolytic and hydrolytic effects in the pore solution leading to the formation of potentially complexing degradation products. The objective was to study the potential effect of radiolyzed superplasticizers contained in cement-based materials on radionuclide uptake. The Eu speciation and solubility with organic ligands resulting from the degradation of SPs were studied for the two solutions and the results were compared. Two different SPs were selected, a polycarboxylate ether and a polynapthalene sulfonate. Two different protocols were followed: direct irradiation of the solution containing the superplasticizer, and irradiation of the compacted cement sample followed by extraction of the pore water. Solubility enhancements observed in artificial cement waters are not representative of real cement pore water interactions, in agreement with other studies. Finally, the effects of alkaline hydrolysis and radiolysis of SPs on Eu solubility in pore water are limited.

The chemical journey of Europium(III) through winter rye (Secale cereale L.) - Understanding through mass spectrometry and chemical microscopy

A combination of biochemical preparation methods with microscopic, spectroscopic, and mass spectrometric analysis techniques as contemplating state of the art application, was used for direct visualization, localization, and chemical identification of europium in plants. This works illustrates the chemical journey of europium (Eu(III)) through winter rye (Secale cereale L.), providing insight into the possibilities of speciation for Rare Earth Elements (REE) and trivalent f-elements. Kinetic experiments of contaminated plants show a maximum europium concentration in Secale cereale L. after four days. Transport of the element through the vascular bundle was confirmed with Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray analysis (EDS). For chemical speciation, plants were grown in a liquid nutrition medium, whereby Eu(III) species distribution could be measured by mass spectrometry and luminescence measurements. Both techniques confirm the occurrence of Eu malate species in the nutrition medium, and further analysis of the plant was performed. Luminescence results indicate a change in Eu(III) species distribution from root tip to plant leaves. Microscopic analysis show at least three different Eu(III) species with potential binding to organic and inorganic phosphate groups and a Eu(III) protein complex. With plant root extraction, further europium species could be identified by using Electrospray Ionization Mass Spectrometry (ESI MS). Complexation with malate, citrate, a combined malate-citrate ligand, and aspartate was confirmed mostly in a 1:1 stoichiometry (Eu:ligand). The combination of the used analytical techniques opens new possibilities in direct species analysis, especially regarding to the understanding of rare earth elements (REE) uptake in plants. This work provides a contribution in better understanding of plant mechanisms of the f-elements and their species uptake.

New europium-doped carbon nanoparticles showing long-lifetime photoluminescence: Synthesis, characterization and application to the determination of tetracycline in waters

The growing appearance of antibiotic-resistant strains of microorganisms originated from the widespread use and ubiquitous presence of such drugs is a major concern in the world. The development of methodologies able to detect such substances at low concentration in real water samples is mandatory to overcome this problem. Europium(III) is known to form complexes with tetracycline (TC) with photoluminescent characteristics useful for TC determination. In the present work, we synthesized for the first time carbon nanoparticles (CN) showing delayed photoluminescence using a Europium(III) doping synthesis. The new material (PCNEu) was characterized both morphologically and spectroscopically, showing an analytical photoluminescent signal in presence of TC, arising from the ⁵D₀→⁷F₂ transition of europium, one hundred times higher than that of the europium salt alone in presence of the antibiotic. This enhancement is a consequence of the amplifying effect exerted by nanoparticle structure itself, leading to an efficient synergistic "antenna effect" in the system PCNEu - TC. The analytical signal is affected both by pH and the nature of the buffer used, and it allows the detection of tetracycline in waters with a limit of detection of 2.18 nM and recoveries between 90 and 110%. The analytical performance of the developed methodology enables having lower limits of detection than other luminescent and chemiluminescent reported methodologies.

Bifunctional Europium for Operando Catalyst Thermometry in an Exothermic Chemical Reaction

Often the reactor or the reaction medium temperature is reported in the field of heterogeneous catalysis, even though it could vary significantly from the reactive catalyst temperature. The influence of the catalyst temperature on the catalytic performance and vice versa is therefore not always accurately known. We here apply EuOCl as both solid catalyst and thermometer, allowing for operando temperature determination. The interplay between reaction conditions and the catalyst temperature dynamics is studied. A maximum temperature difference between the catalyst and oven of +16 °C was observed due to the exothermicity of the methane oxychlorination reaction. Heat dissipation by radiation appears dominating compared to convection in this set-up, explaining the observed uniform catalyst bed temperature. Application of operando catalyst thermometry could provide a deeper mechanistic understanding of catalyst performances and allow for safer process operation in chemical industries.

Speciation and spatial distribution of Eu(III) in fungal mycelium

Europium, as an easy-to-study analog of the trivalent actinides, is of particular importance for studying the behavior of lanthanides and actinides in the environment. Since different soil organisms can influence the migration behavior of these elements, a detailed knowledge of these interaction mechanisms is important. The aim of this study was to investigate the interaction of mycelia of selected wood-inhabiting (S. commune, P. ostreatus, L. tigrinus) and soil-inhabiting fungi (L. naucinus) with Eu(III). In addition to determining the Eu(III) complexes in the sorption solution, the formed Eu(III) fungal species were characterized using scanning transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy, chemical microscopy in combination with the time-resolved laser-induced fluorescence spectroscopy. Our data show that S. commune exhibited significantly higher Eu(III) binding capacity in comparison to the other fungi. Depending on fungal strain, the metal was immobilized on the cell surface, in the cell membranes, and within the membranes of various organelles, or in the cytoplasm in some cases. During the bioassociation process two different Eu(III) fungal species were formed in all investigated fungal strain. The phosphate groups of organic ligands were identified as being important functional groups to bind Eu(III) and thus immobilize the metal in the fungal matrix. The information obtained contributes to a better understanding of the role of fungi in migration, removal or retention mechanisms of rare earth elements and trivalent actinides in the environment.

Comprehensive evaluation of cobalt incorporated cryptomelane-type manganese oxide molecular sieve as an efficient adsorbent for enhanced removal of europium from wastewater systems

Extraction of radionuclide contaminants from wastewater systems has recently drawn widespread attention, and then developing a novel and green extracting technology has also become an enormous challenge. Herein, a facile hydrothermal method was employed to fabricate cobalt-incorporated cryptomelane-type manganese oxide molecular sieve (Co-OMS-2) for extraction Eu(III) from wastewater under diverse experimental conditions. All kinds of characterized techniques, such as SEM, TEM, XRD, FTIR, BET, EDS and XPS had verified the qualified synthesis process and splendid structural features of the Co-OMS-2. The maximum adsorption capacity of Co-OMS-2 was 7.62 × 10^-4 mol/g for Eu(III) at 298 K, which was superior than primarily traditional materials reported previous literatures. The high adsorption capacity of Eu(III) onto Co-OMS-2 was primarily attributed to high specific surface area and abundant surface functional groups, and the interactions were mainly contributed to strong surface complexation and electrostatic attraction. Under the condition of low pH, the outer-sphere surface complexation and cation exchange were primary mechanisms to Eu(III) adsorption onto Co-OMS-2 composites, while inner-sphere surface complexation was mainly assigned to Eu(III) adsorption onto Co-OMS-2 under the high pH sections. The Co-OMS-2 composite achieved equilibrium in a relatively short time, and this excellent performance was conducive to the treatment of Eu(III) under the extreme emergency conditions. In view of the extraordinary adsorption capacity and recycled reusability, the Co-OMS-2 composites can be as prospective adsorbents adopted for the extraction of Eu(III) in real wastewater management.

Eu2 P2 S6 : The First Rare-Earth Chalcogenophosphate Exhibiting Large Second-Harmonic Generation Response and High Laser-Induced Damage Threshold

Metal chalcogenophosphates are receiving increasing interest, specifically as promising infrared nonlinear optical (NLO) candidates. Here, a rare-earth chalcogenophosphate Eu₂ P₂ S₆ crystallizing in the monoclinic noncentrosymmetric space group Pn was synthesized using a high-temperature solid-state method. Its structure features isolated [P₂ S₆ ]^4- dimer, and two types of EuS₈ bicapped triangular prisms. Eu₂ P₂ S₆ exhibits a phase-matchable second-harmonic generation (SHG) response ≈0.9×AgGaS₂ @2.1 μm, and high laser-induced damage threshold of 3.4×AgGaS₂ , representing the first rare-earth NLO chalcogenophosphate. The theoretical calculation result suggests that the SHG response is ascribed to the synergetic contribution of [P₂ S₆ ]^4- dimers and EuS₈ bicapped triangular prisms. This work provides not only a promising high-performance infrared NLO material, but also opens the avenue for exploring rare-earth chalcogenophosphates as potential IR NLO materials.

Lanthanoid-doped quaternary garnets as phosphors for high brightness cathodoluminescence-based light sources

Gadolinium-yttrium- aluminum-gallium garnets (GYAGG) doped and codoped with Eu, Tb, and Ce were manufactured as ceramics to develop long-wavelength phosphors for high-brightness white light sources based on cathodoluminescence (CL). The CL light yield (LY) of Tb-doped ceramics at high-intensity electron beam excitation is shown to be more than twice as high as that of the conventional phosphor YAG:Ce, whereas codoping with Eu to redshift the chromaticity results in reducing the LY approximately to the level of YAG:Ce. The LY might be substantially improved by using a mix of Tb- and Eu-doped GYGAG powders instead of a single codoped GYGAG to produce ceramic phosphor. The high LY is explained by favorable contribution of Gd sublattice in excitation transfer to activator ions. Chromaticity of phosphors GYGAG:Tb, Eu can be tuned in a wide range by varying the ratio of Tb to Eu concentration. They are radiation resistant and stabile in the temperature range from 300 to 450 K.

The pH-dependent reactions in the sonochemical synthesis of luminescent fluorides: The quest for the formation of KY3F10 crystal phases

In this study Eu³⁺-doped yttrium fluorides were designed by ultrasound-assisted processes at different pH values (4.0-9.0). This novel strategy has enabled to obtain materials with intriguing morphologies and modulated crystal structures: α-KY₃F₁₀, δ-KY₃F₁₀·xH₂O, and Y(OH)_3-xF_x. To date, the literature has primarily focused only on the α-phase of KY₃F₁₀. Yet, explaining the formation of the mostly uncharted δ-phase of KY₃F₁₀ remains a challenge. Thus, this paper offers the key to synthesizing both the α and the δ-phases of KY₃F₁₀ and also reports the first ultrasound-assisted process for the preparation of yttrium hydroxyfluorides. It is also unraveled the connection between the different pH-dependent reactions and the formation mechanisms of the compounds. In addition to this, the unique features of the Eu³⁺ ion have allowed to conduct a thorough study of the different materials and have endowed the compounds with photoluminescent properties. The results underscore a highly tunable optical response, with a wide gamut of color emissions (from orangish to red hues), lifetimes (from 7.9 ms to 1.1 ms) and quantum efficiencies (98-28%). The study unveils the importance of sonochemistry in obtaining luminescent fluorides with controlled crystal structures that can open up new avenues in the synthesis and design of inorganic materials.

Kinetics and mechanism of Eu(III) transfer in tributyl phosphate microdroplet/HNO3 aqueous solution system revealed by fluorescence microspectroscopy

In this study, we reveal an Eu(III) extraction mechanism at the interface between HNO₃ and tributyl phosphate (TBP) solutions using fluorescence microspectroscopy. The mass transfer rate constant at the interface is obtained from the analysis of fluorescence intensity changes during the forward and backward extractions at various HNO₃ and TBP concentrations to investigate the reaction mechanism. This result indicates that one nitrate ion reacts with Eu(III) at the interface, whereas TBP molecules are not involved in the interfacial reaction, which is different from the results obtained using the NaNO₃ solution in our previous study. We demonstrate that the chemical species of Eu(III) complex with nitrate ion and TBP in the aqueous solution play an important role for the extraction mechanism. The rate constants of the interfacial reactions in the forward and backward extractions are (4.0-5.0) × 10^-7 m M^-1 s^-1 and (3.2-3.3) × 10^-6 m s^-1, respectively. We expect that our revealed mechanism provides useful and fundamental knowledge for actual solvent extraction.

Carbazole-Functionalized Dipicolinato LnIII Complexes Show Two-Photon Excitation and Viscosity-Sensitive Metal-Centered Emission

Eu^III and Yb^III complexes with the carbazole-dipicolinato ligand dpaCbz^2-, namely K₃[Eu(dpaCbz)₃] and K₃[Yb(dpaCbz)₃], were isolated. The Eu^III complex displayed metal-centred emission upon one-photon excitation with a sensitized emission efficiency Φ L Ln of 1.8±0.3 %, corresponding to an intrinsic emission efficiency Φ Ln Ln of 46% and a sensitization efficiency of η_sens 3.9%, with an emission lifetime of the emissive state τ of 1.087±0.005 ms. The Yb^III complex displayed Φ L Ln of 0.010±0.001 %, and a τ of 2.32±0.06 μs. The Eu^III-centred emission was sensitized as well upon two-photon excitation and a two-photon absorption cross-section σ_2PA of 63 GM at 750 nm was determined for the complex. The one- or two-photon sensitized emission intensity of the Eu^III complex changes by more than two-fold when the solvent viscosity is varied in the range 0.5 - 200 cP and the emission is independent of dissolved oxygen. The Yb^III complex displays a change in emission intensity as well. However, in this case, a dependence of the emission intensity on dissolved oxygen content was observed.

Optical thermometry based on europium doped self-activated dual-emitting LiCa3ZnV3O12 phosphor

In this study, rare-earth-doped self-activated LiCa₃ZnV₃O₁₂ (LCZV) vanadate phosphors were preparation by a high-temperature solid-state reaction. Their crystal structure, non-contact temperature sensing, and luminescence properties were studied deeply. Excited by ultraviolet light at 340 nm, the emission of [VO₄]^3- group and the Eu³⁺ ions were monitored. The highest strength emission peaks at 470 nm and 610 nm for [VO₄]^3- and Eu³⁺, respectively, provide favorable signal identification for estimating temperature. Due to thermal quenching behavior and energy transfer, the FIR (Fluorescence Intensity Ratio) from Eu³⁺ to [VO₄]^3- exhibits excellent sensitivity performance at 303 K - 523 K. In the meantime, the maximum absolute and relative sensitivities of the obtained phosphors are 0.0068 K^-1 and 1.18 % K^-1, which are overtopped to those reported previously. Furthermore, for the luminescent color of the CIE diagram with a strong temperature effect, the color coordinate could be verified from (0.2871, 0.3416) to (0.4121, 0.3420), which was matched well with the linear equation. Consequently, the Eu³⁺ doped LCZV phosphor not only can be used for high-temperature environmental safety signals but also is an extraordinary viable material in the field of optical sensing.

Luminescent determination of propineb fungicide by using a carbon quantum dots-europium ions system

We propose a modification of lanthanide-sensitized luminescence (LSL) to increase the selectivity and sensitivity of analytical methods based on this detection. LSL consists in the formation of complexes of lanthanide ions and organic compounds. Then, an intramolecular energy transfer occurs from the excited state of the ligand (organic analyte) to the emitting level of the lanthanide. The utilization of luminescent nanoparticles (carbon quantum dots, CQDs) in LSL systems can enhance their sensitivity and selectivity. CQDs can react with lanthanide ions through their carboxylic groups. These systems can thus be used as time-resolved luminescent probes. Propineb (PPN), a well-known dithiocarbamate fungicide, has been selected as the target analyte to show the advantages of using CQDs in LSL systems. The method proposed is based on the quenching produced by PPN in europium-CQDs luminescence, obtaining a detection limit of 0.03 μg mL^-1 PPN and a method detection limit of 3 mg kg^-1 in capers (bud and fruit), fulfilling the maximum residue limit in these samples (25 mg kg^-1). The results showed that the use of nanoparticles in LSL systems may provide novel and simple analytical methods for the screening of contaminants in the agri-food sector.

Eu-Doped Pyrochlore Crystal Nano-Powders as Fluorescent Solid for Fingerprint Visualization and for Anti-Counterfeiting Applications

Undoped Y₂Sn₂O₇ and Eu³⁺ doped Y₂Sn₂O₇ samples with doping concentrations 7%, 8%, 9%, and 10% are successfully synthesized by the co-precipitation method. A complete structural, morphological, and spectroscopic characterization is carried out. XRD measurements reveal that samples crystallize in the pure single pyrochlore phase and Eu³⁺ ions occupy sites with D_3d symmetry. After mechanical grinding, the average crystallite size is less than 100 nm for all compositions. Optical characterization shows emission from the ⁵D₀ level towards the lower lying ⁷F_0,1,2,3,4 levels. The CIE color coordinates of all the pyrochlore phosphors are very close to those of the ideal red light. For the visualization of latent fingerprints, different surfaces are tested, including difficult ones (wood and ceramic), with excellent results. All three levels of fingerprint ridge patterns are visualized: core (Level 1), bifurcation and termination (Level 2), and sweat pores (Level 3). Moreover, our nano-powders are used to prepare a stable fluorescent ink.

Not just a background: pH buffers do interact with lanthanide ions-a Europium(III) case study

The interaction between Eu(III) ion and different pH buffers, popular in biology and biochemistry, viz. HEPES, PIPES, MES, MOPS, and TRIS, has been studied by solution nuclear magnetic resonance spectroscopy (NMR) and time-resolved laser-induced fluorescence spectroscopy (TRLFS) techniques. The Good’s buffers reveal non-negligible interaction with Eu(III) as determined from their complex stability constants, where the sites of interaction are the morpholine and piperazine nitrogen atoms, respectively. In contrast, TRIS buffer shows practically no affinity towards Eu(III). Therefore, when investigating lanthanides, TRIS buffer should be preferred over Good’s buffers.

Utility of Silver-nanoparticles for Nano Spectrofluorimetric Determination of Meropenem and Ertapenem: Bio-analytical Validation

Bio-analytical, nano-quantitative spectrofluorimetric estimation of two non-classical β-lactam antibiotics; meropenem (MP) and ertapenem (EP) is presented. The method is based on the enhancement of the fluorescence intensity of MP-Eu³⁺/EP-Eu³⁺ with silver nanoparticles (AgNPs). AgNPs were synthesized and characterized by UV and transmission electron microscope (TEM). The plasmon resonance produced an intense absorption maximum at 398.0 nm. TEM micrograph showed the particle morphology with an average particles size of 13.0 ± 2.95 nm. The fluorescence intensities were measured against blank reagents at λem of 396.0 nm and 405.0 nm after excitation at λex 305.0 nm and 303.0 nm for MP and EP, respectively. Under optimum conditions, the relative fluorescence intensity showed a good linear relationship with the concentration ranges of 4.0-14.0 and 4.0 -12.0 ng/mL with excellent correlation coefficients of 0.9998 and 0.9997, and limit of detection of 0.84 and 0.86 ng/mL for MP and EP, respectively. The method was successfully applied for direct analysis of MP and EP in their drug substances and pharmaceutical vials. The significant, sensitivity and practicality of the method facilitated MP detection in real plasma samples. Bio-analytical validation was performed according to FDA. The method was rectilinear over the ranges of, 5.0 -75.0 μg/mL plasma. Interestingly, this described system has a promising benefit for various applications exploiting the dramatically enhanced-fluorescence occurrence.

Insight into the adsorption of europium(III) on muscovite and phlogopite: Effects of pH, electrolytes, humic substances and mica structures

Europium(III), i.e., Eu(III), is chemically analogous to the trivalent lanthanides (Ln) and actinides (An). A good understanding of the adsorption behaviour of Eu(III) on mica group minerals is critical to the safety evaluation of the radioactive contamination. Nevertheless, the structural complexity of micaceous minerals makes it difficult to draw a consistent conclusion in the study of Eu(III) migration. In this work, we contrastively studied Eu(III) adsorption on dioctahedral muscovite and trioctahedral phlogopite as functions of pH, ionic strength, background electrolytes, interaction sequence, and fulvic acid (FA). Batch experiments showed that Eu(III) adsorption on both micas was strongly dependent on pH but quite independent on ionic strength that is determined by Na⁺. Planar sites are available on both muscovite and phlogopite while interlayer sites only on phlogopite under Na⁺ and Ca²⁺ electrolytes (not for K⁺ and Cs⁺). An interlayer expansion of phlogopite, as indicated by a newly appeared diffraction peak at ~6° 2-theta, occurred along with Eu(III) adsorption, which was also confirmed by transmission electron microscopy. Furthermore, the initial Eu(III) concentrations, the concentration ratios between Eu(III) and Cs⁺, and the reaction sequences of Eu(III)-electrolytes-FA affected both the adsorption behaviour of Eu(III) and reversely the structural alteration of phlogopite. The sequential extraction showed that the adsorbed Eu(III) was mainly in the ion-exchangeable form while the addition of FA could increase the portion of coordinative species. The currently proposed Eu(III) adsorption mechanism can shed new light on predicting the migration of Ln/An(III) at the mica-rich solid-liquid interface on a molecular scale.

Pseudo isotope dilution (PID) as an approach for correcting barium-related spectral interferences on the measurement of europium by inductively coupled plasma mass spectrometry (ICP-MS)

Pseudo isotope dilution (PID) was suggested as a simple and practical approach for the correction of barium-related spectral interferences on the measurement of europium by inductively coupled plasma mass spectrometry (ICP-MS). The interferents, i.e. oxides and hydroxides of barium, were regarded as pseudo europium isotopes. An equation for calculating the concentration of europium was deduced and the net contribution of europium isotopes can be obtained by measuring the signal intensity ratios of ¹⁵¹I/¹⁵³I in a sample, a europium standard, and a barium standard, respectively. The validity of the approach was confirmed by the determination of europium in standard solutions with different concentrations of barium. Determination of europium in river water and seawater certified reference materials was carried out, whose results were in coincidence with reference values.

Luminescent lanthanide(III) complexes of DTPA-bis(amido-phenyl-terpyridine) for bioimaging and phototherapeutic applications

We report here a series of coordinatively-saturated and thermodynamically stable luminescent [Ln(dtntp)(H₂O)] [Ln(III) = Eu (1), Tb (2), Gd (3), Sm (4) and Dy (5)] complexes using an aminophenyl-terpyridine appended-DTPA (dtntp) chelating ligand as cell imaging and photocytotoxic agents. The N,N″-bisamide derivative of H₅DTPA named as dtntp is based on 4'-(4-aminophenyl)-2,2':6',2″-terpyridine conjugated to diethylenetriamine-N,N',N″-pentaacetic acid. The structure, physicochemical properties, detailed photophysical aspects, interaction with DNA and serum proteins, and photocytotoxicity were studied. The intrinsic luminescence of Eu(III) and Tb(III) complexes due to f → f transitions used to evaluate their cellular uptake and distribution in cancer cells. The solid-state structure of [Eu(dtntp)(DMF)] (1·DMF) shows a discrete mononuclear molecule with nine-coordinated {EuN₃O₆} distorted tricapped-trigonal prism (TTP) coordination geometry around the Eu(III). The {EuN₃O₆} core results from three nitrogen atoms and three carboxylate oxygen atoms, and two carbonyl oxygen atoms of the amide groups of dtntp ligand. The ninth coordination site is occupied by an oxygen atom of DMF as a solvent from crystallization. The designed probes have two aromatic pendant phenyl-terpyridine (Ph-tpy) moieties as photo-sensitizing antennae to impart the desirable optical properties for cellular imaging and photocytotoxicity. The photostability, coordinative saturation, and energetically rightly poised triplet states of dtntp ligand allow the efficient energy transfer (ET) from Ph-tpy to the emissive excited states of the Eu(III)/Tb(III), makes them luminescent cellular imaging probes. The Ln(III) complexes show significant binding tendency to DNA (K ~ 10⁴ M^-1), and serum proteins (BSA and HSA) (K ~ 10⁵ M^-1). The luminescent Eu(III) (1) and Tb(III) (2) complexes were utilized for cellular internalization and cytotoxicity studies due to their optimal photophysical properties. The cellular uptake studies using fluorescence imaging displayed intracellular (cytosolic and nuclear) localization in cancer cells. The complexes 1 and 2 displayed significant photocytotoxicity in HeLa cells. These results offer a modular design strategy with further scope to utilize appended N,N,N-donor tpy moiety for developing light-responsive luminescent Ln(III) bioprobes for theranostic applications.

Exploration of photophysical behavior of lanthanide complex and its hybrids

The present work envisioned to synthesize europium complexes [Eu-(L)₃-phen] (where, L is 4,4,4-Trifluoro-1-(2-furyl)-1,3-butanedione (TFB), phen-1,10 -phenanthroline) and its hybrids via embedding pure complex into silica and PMMA. The sol-gel method was adopted for incorporating europium complex into silica matrix as [Eu-(L)₃-phen]-silica and this method was proved to be highly effective and excellent approach for obtaining such lanthanide hybrid material. Another hybrid was prepared by incorporating complex into PMMA (polymethyl methyl acrylate), an organic polymer, transformed into flexible thin film. The structure of the [Eu-(L)₃-phen] was elucidated using various spectroscopic techniques, moreover Sparkle model calculation were utilized for prediction of ground state geometry. The photophysical properties of pure complex [Eu-(L)₃-phen] and its hybrids were studied in detail and compared. The incorporation of pure complex into PMMA is highly supportive to enhance the stability of complex as evident from enhanced luminescent intensity, intensity ratio value 6.52, longer lifetime value 842μs and higher quantum efficiency 77% over pure complex. The organic polymer PMMA is expected to interact well with europium complex via antenna effect. The use of such inorganic and organic entities for hybrid preparation purposefully overcomes the flaws of lanthanide complexes in terms of thermal stability and mechanical strength. The promising and fascinating properties of synthesized lanthanide hybrids are fruitful in material research.

Evaluation of component additive modelling approach for europium adsorption on 2:1 clays: Experimental, thermodynamic databases, and models

This study evaluates the component additive approach for Eu adsorption on mixtures of smectite and illite, which are the most common clays used as barriers for contaminant retention in waste repositories. A thorough set of Eu adsorption data for Na-exchanged smectite and illite that encompasses a wide range of pH values, ionic strengths, and Eu concentrations was provided. This database is likely one of the largest sorption databases available for Eu in 2:1 clays, making it appropriate for sorption model calibration. The main adsorption mechanisms considered were surface complexation, on weak and strong clay edge sites, and cation exchange. Further, the role of principal ions, which are naturally leached from clays, as competitive factors for Eu retention, was evaluated in the modelling calculations. The main uncertainties related to the modelling procedures and the use of different thermodynamic data on sorption modelling were outlined. The reactions and parameters successful in modelling Eu adsorption on individual clays were used without any modification to model Eu adsorption on illite/smectite mixtures, wherein only the relative mineral proportions were considered. The fit of the sorption data in the mixed clay system was satisfactory, indicating that, in 2:1 clays, Eu sorption is an additive process, which stresses the predictive capacity of the component additive approach in these systems. This is an important support for assessing the performance of barrier materials for contaminant migration under different geochemical conditions.

Synthesis of potential Ca-Mg-Al layered double hydroxides coated graphene oxide composites for simultaneous uptake of europium and fulvic acid from wastewater systems

High background electrolyte and natural organic matter are favorable to migration of hazardous radionuclides in geochemical repository. Herein, Ca-Mg-Al layered double hydroxide coated onto graphene oxide (Ca-Mg-Al LDH/GO) composites were successfully synthesized, characterized and adopted to decontaminate Eu(III) and fulvic acid (FA) under diverse experimental conditions. Diverse concentration gradients and different addition sequences on Eu(III) and FA were also obtained, which revealed different interaction mechanisms. The experimental results displayed that the coexistence of FA and Eu(III) respectively promoted adsorption performance of Eu(III) and FA under the ternary systems. The acquired Ca-Mg-Al LDH/GO composites were adopted to remove Eu(III) and FA, which further illustrated excellent chemo-physical stability and adsorption capacity of 1.12 × 10^-3 mol/g and 3.54 × 10^-4 mol/g, respectively. The remarkable adsorption performances of Ca-Mg-Al LDH/GO were confirmed through kinetic procedures and depending-temperature isotherms, illustrating that the kinetics processes were simulated using pseudo-second-order pattern, and the adsorption isotherms were splendidly simulated using Langmuir pattern. XPS spectrum analysis revealed that these containing oxygen groups took significant part in the restricting of Eu(III) and FA onto the surfaces of Ca-Mg-Al LDH/GO composites. In view of experimental results, the Ca-Mg-Al LDH/GO composites can be as potential adsorbents with availably recycled reusability for the decontamination of Eu(III) and FA from nuclear fuel partition or nuclear wastewater systems.

Synergistic Extraction of Europium (III) using Di-n-Butylsulfoxide and PicrolonicAcid

AIM AND OBJECTIVE

Europium (Eu(III))isa rare-earth metal, the softest, least dense, and most volatile member of lanthanides. It is greatly applied in control rods of nuclear reactors. Although various extraction methods of Eu(III)have been reported, we present a novel mixture ofeasily available extractants in optimizedexperimental conditions to extract it efficiently, quickly, and cost-effectively.

MATERIALS AND METHODS

Physical-chemical conditions (e.g. pH, equilibration time, temperature, europium concentration, extractants concentration, presence of specific metal ions) were optimized. The extractantspicrolonic acid (HPA) and di-n-butylsulfoxide (DBSO) were thoroughly mixed at equal concentrationin chloroform. Standard Eu(III) solution was used for method accuracy.Reagent blank was prepared under identical conditions but without metal ions.Using the metallochromic dye arsenazoIII as blank, absorbance of Eu(III) was measured spectrophotometricallyat 651 nm. Distribution ratio (i.e.Eu(III) concentration in aqueous phase before and after extraction) defined the extraction yield.

RESULTS

HPA/DBSO mixture (0.01 M)had a synergistic effect on Eu(III) extraction (1.19×10-5 mole/dm3) achieving a maximum yield (≥99%) at pH2, during 5 minutes equilibration,atroom temperature.Eu(III) extraction was reduced depending on the nature but not on the metal ions concentration. Extractants could be recycled four times without consequent degradation. Deionized water (dH2O) was the best strippantbesides its availability and low-cost. The composition of the extracted adduct was defined as Eu(PA)3.2DBSO.

CONCLUSION

This alternative method was stable, simple, rapid, cost-effective, reliable, accurate and sensitive.It could be used forEu(III) extraction and refining on a pilot plant scale.

Penetration of fission product ions into complex solids and the effect of ionic wash methods

During washing of radiologically impacted building surfaces, penetration of radionuclide ions into complex solids associated with these surfaces may occur. This study investigates the penetration of 137Cs, 85Sr, and 152Eu solutions into numerous common building materials and radionuclide behavior when these materials were exposed to a static bath or low-pressure flow of tap water, 0.1 M potassium chloride (KCl), and 0.5 M KCl. The decontamination efficacy and the depth profile for residual contamination were measured to determine the conditions under which applying a wash solution has benefit compared to physically removing the surface material. On asphalt, 70-80% of the radionuclides were found to be within 0.02 mm of the surface. Concrete is more porous than asphalt, and 80% of the radionuclides were within 0.2 mm of the surface for 137Cs and 152Eu and 50-80% for 85Sr. Water effectively removed all contaminants from hard nonporous surfaces. Finally, this paper illustrates that a wash penalty factor concept-defined as ratio of the depth at which 50% of the radioactivity is found in the washed sample divided by the depth at which 50% of radioactivity is found in the control-can serve as a way to quantify whether the wash method increases the depth at which contamination penetrates into the material and thus the material becomes more difficult to decontaminate.

Synthesis and Evaluation of Europium Complexes that Switch on Luminescence in Lysosomes of Living Cells

A set of four luminescent EuIII complexes bearing an extended aryl-alkynylpyridine chromophore has been studied, showing very different pH-dependent behaviour in their absorption and emission spectral response. For two complexes with pKa values of 6.45 and 6.20 in protein-containing solution, the emission lifetime increases very significantly following protonation. By varying the gate time during signal acquisition, the 'switch-on' intensity ratio could be optimised, and enhancement factors of between 250 to 1330 were measured between pH 8 and 4. The best-behaved probe showed no significant emission dependence on the concentration of endogenous cations, reductants, and serum albumin. It was examined in live-cell imaging studies to monitor time-dependent lysosomal acidification, for which the increase in observed image brightness due to acidification was a factor of 50 in NIH-3T3 cells.

A dual-response ratiometric fluorescent sensor by europium-doped CdTe quantum dots for visual and colorimetric detection of tetracycline

Residues in animal food and drinking water caused by the abuse of antibiotics lead to cell resistance and many chronic diseases in the human body. Therefore, it has become an inevitable trend to develop a fast, easy-to-use, on-site/real-time visualization method for the detection of antibiotics. Herein, we report a dual-response ratiometric fluorescence sensor which is fabricated by chelating europium ions (Eu³⁺) onto cadmium telluride quantum dots (CdTe QDs) for real-time and visible detection of tetracycline (TC). With the TC addition, the fluorescence of probe can be seen by the naked eye, from green to yellow and finally to red, exhibiting a dosage-sensitive and broad-chromatic detection strategy for TC. The fluorescence intensity ratio of I₆₁₆/I₅₁₂ of Eu/CdTe QDs sensor displays a good linear relation to TC concentrations in the range of 0-80 μM with a limit of detection (LOD) of 2.2 nM. In addition, the sensor can visually detect 200 nM TC in actual samples, which is lower than the maximum residue limit (MRL) of the safety standard. The methodology reported here opens a window toward the real applications of fluorescent and shows the wide applicability in pursuing the concepts simple, rapid, visual, and real-time for food safety and environmental protection.

Dual-functional lanthanide metal organic frameworks for visual and ultrasensitive ratiometric fluorescent detection of phosphate based on aggregation-induced energy transfer

Phosphate (Pi) not only plays a significant role in physiological processes, but also is an important indicator for aquatic ecosystems. The dual-functional lanthanide metal organic frameworks (MOFs) were synthesized for visual and ultrasensitive ratiometric fluorescent detection of Pi based on aggregation-induced energy transfer. In the MOFs material, ciprofloxacin (CIP) functions as an energy donor and results in the fluorescence enhancement of Eu³⁺; the introduction of pyromellitic acid can cause the aggregation of the CIP-Eu³⁺ complex, and red characteristic fluorescence of Eu³⁺ at 614 nm is further enhanced (about 40 times). When Pi is added to the MOFs solution, CIP is released from the MOFs, red fluorescence of Eu³⁺ is quenched and blue fluorescence of CIP is simultaneously recovered, thereby a ratiometric fluorescent probe for the detection of Pi was fabricated. The fluorescent response based on intermolecular energy transfer of the CIP-Eu³⁺ complex is very sensitive to Pi. The limit of detection (3σ/K) of the probe is ultrasensitive and attains 4.4 nM. The possible interferential substances such as 17 common metal ions and 14 anions investigated do not interfere with the Pi detection. The ratiometric fluorescent probe has been successfully used in the determination of Pi in real human urine and lake water samples. This work may supply a new strategy for fabricating ratiometric fluorescent probe and a prospective application in biological and environmental samples.

Dopamine Sensing Based on Ultrathin Fluorescent Metal-Organic Nanosheets

The importance of dopamine (DA) detection as a biomarker for several diseases, especially Parkinson''s disease, has persuaded scientists to develop new nanomaterials for efficient sensing of DA in clinical samples. Ultrathin metal-organic nanosheets due to their exceptional thickness, large surface area, and flexibility are endowed with many accessible active sites and optimal surface interaction with the target analyte molecules. In this regard, a novel layered fluorescent metal-organic nanomaterial with a honeycomb topology based on europium, [Eu(pzdc)(Hpzdc)(H₂O)]_n (ECP) (H₂pzdc = 2,3-pyrazine dicarboxylic acid), was synthesized. X-ray crystallography revealed that the 3D supramolecular architecture of ECP is constructed from noncovalent interactions of coordinated water molecules between the 2D layers along the b axis. These layers that are only ∼4 nm thick were conveniently separated through ultrasound-induced liquid phase exfoliation. Optical studies show that the reduction of ECP thickness enhances the fluorescence intensity and serves as an efficient optical marker for DA detection. ECP nanoflakes exhibited fast response and high selectivity for DA detection in clinical samples. Good linearity for DA detection in the range of 0.1-10 μM with a detection limit of 21 nM proves the potential of ECP nanoflakes in DA sensing applications.

Adsorption and mechanistic study of the invasive plant-derived biochar functionalized with CaAl-LDH for Eu(III) in water

Herein, we developed the invasive plant-derived biochar (IPB) functionalized with CaAl-LDH at five mass ratios using a physical mixture method, assessed their adsorption perform for Eu(III), and explored the relative mechanisms. Results show that the IPB successfully loaded CaAl-LDH in five composites and their Eu(III) sorption affinities were strongly affected by solution pH, contact time, temperature, and the mass ratio of LDH and IPB. All the sorpiton process for Eu(III) occurred on the heterogeneous surface of five composites and the boundary layer diffusion limited the chemical sorption rate. Interestingly, the CaAl-LDH/IPB composite with high ratio of IPB had higher sorption capacity than the one with high ratio of LDH due to larger porosity of the former. Three mechanisms containing ion exchange between Al and Eu ions, surface complexation with carboxyl- and oxygen-containing functional groups, and precipitation were involved in the Eu(III) sorption, but the dominant sorption mechanism for each CaAl-LDH/IPB composite differed with different mass ratio of CaAl-LDH and IPB. In composite with more IPB (e.g., CaAl-LDH/IPB-13), both ion exchange and surface complexes dominated the sorption process and the intensity of Eu³⁺ was identified with the one of Eu₂O_3. Whereas in composites with high LDH, ion exchange dominated the sorption and the intensity of Eu³⁺ was obviously higher than the one of Eu₂O₃. This research will provide a new perspective for the application of the LDH/biochar materials.

Synthesis, Structure Study, First-Principles Investigations and Luminescence Properties of Europium and Terbium Complexes

The synthesis of 1-benzyl-2-((2-Aminoethyl) amino)-5-oxopyrrolidine-3,4-diyl diacetate (boad), an oxopyrrolidine type ligand; designed to coordinate lanthanides (Eu³⁺ and Tb³⁺) to get luminescent material. The target complexes showed good photoluminescence properties, which indicate that this type of compound can be used as sensitizers having luminescence for the green (Tb³⁺) and red (Eu³⁺) emission. The obtained results revealed that sensitizer efficiency can be improved by adding ligands like acac (Eu(acac)₃, which has also enhanced the luminescence quantum output and period for Eu³⁺ ions. The ground state geometries were developed by using density functional theory at B3LYP/6-31G** level. The charge transfer analysis and electronic properties were performed. The Europium and Terbium complexes formation with boad ligand was explored based on molecular electrostatic potential, MDC-q charges, and frontier molecular orbitals (FMOs) analysis.