A portable europium complex-loaded fluorescent test paper combined with smartphone analysis for the on-site and visual detection of mancozeb in food samples.

The on-site detection of mancozeb in food samples holds immense value for food safety. A red-fluorescent europium complex (Eu-PYDC-Phen) has been prepared and employed as a fluorescence probe for mancozeb detection. The optimized probe suspension exhibits excellent detection performances, including a wide linear range (0-0.24 mM), low detection limit (65 nM), rapid response (2 mins) and high selectivity. Moreover, a portable detection platform was carefully designed, integrating the Eu-PYDC-Phen-based fluorescent test strips with smartphone color recognition software. This innovative platform enables visual and on-site detection of mancozeb in tomato, apple, and lettuce, achieving satisfactory recovery rates (90.34 to 106.50%). Furthermore, the integration of machine learning techniques based on hierarchical clustering algorithm has the potential to further improve the prediction and decision-making efficiency in mancozeb detection. This work provides an economical, convenient, and reliable strategy for on-site detection of pesticide in agricultural products, thereby making a meaningful contribution to food safety.

Microwave-assisted synthesis of Ni-doped europium hydroxide for photocatalytic degradation of 4-nitrophenol.

Microwave-assisted synthesis method was used to prepare europium hydroxide (Eu(OH)3) and different percentages of 1, 5, and 10 % nickel-doped Eu(OH)3 (Ni-Eu(OH)3) nanorods (NRs). X-ray diffraction study showed a hexagonal phase with an average crystallite size in the range of 21 - 35 nm for Eu(OH)3 and Ni-Eu(OH)3 NRs. FT-IR and Raman studies also confirmed the synthesis of Eu(OH)3 and Ni-Eu(OH)3. The synthesized materials showed rod-like morphology with an average length and diameter between 27 - 50 nm and 8 - 13 nm, respectively. The band gap energies of Ni-Eu(OH)3 NRs were reduced (4.06 - 3.50 eV), which indicates that the doping of Ni2+ ions has influenced the band gap energy of Eu(OH)3. The PL study exhibited PL quenching with Ni doping. The photocatalytic degradation of 4-nitrophenol (4-NP) by the synthesized materials under UV light irradiation was investigated, in which 10 % Ni-Eu(OH)3 NRs showed the best response. A kinetic study was also conducted which shows pseudo-first-order kinetics. Based on this, Ni-Eu(OH)3 NRs have shown a potential to be a UV-light active material for photocatalysis.

Rapid redox-response featured visual ascorbic acid sensor based on simple-assembled europium metal-organic framework.

A facile, fast and visible sensing platform for ascorbic acid (AA) detection has been developed based on self-assembled hydrangea-like europium metal-organic framework (HL-EuMOF). HL-EuMOF was synthesized through a simple one-step mixing process with Eu3+ and 1, 10-phenanthroline-2, 9-dicarboxylic acid at room temperature, which exhibited excellent properties including strong red fluorescence, long decay lifetime (548.623 µs) and good luminescent stability. Based on the specific redox reaction between Fe3+ and AA, the HL-EuMOF@Fe3+ was fabricated with "turn-off" response for AA, where the resulting Fe2+ displayed effective fluorescence quenching ability toward HL-EuMOF. The sensor demonstrated low detection limit (31.94 nM), rapid response time (30 s) and high selectivity. Integration of smartphone-assisted RGB analysis with HL-EuMOF@Fe3+ permitted convenient and visible quantitative determination of AA level. This approach also presented good detection performances in complex human serum and beverage samples, which could provide a valuable tool for AA detection in biomedical research and food industry.

Europium functionalized porphyrin-based metal-organic framework heterostructure and hydrogel for visual ratiometric fluorescence sensing of sulfonamides in foods.

Protecting human health and ensuring food security require the swift and accurate detection of sulfonamides (SAs) residues in foods. Herein, we proposed an Eu-postfunctionalized bimetallic porphyrin metal-organic framework (PCN-221(Zr/Ce)@Eu-DPA-H4btec) synthesized solvothermally for fluorescence sensing. The PCN-221(Zr/Ce)@Eu-DPA-H4btec fluorescent sensor demonstrated excellent stability and high selectivity to SAs, and the detection limits of sulfamethazine (SM2), sulfamerazine (SMR), and sulfamethoxydiazine (SMD) were as low as 56 nmol/L, 45 nmol/L, and 56 nmol/L, respectively. The PCN-221(Zr/Ce)@Eu-DPA-H4btec fluorescent sensor was successfully applied for the detection of SM2, SMR, and SMD in real pork and milk samples, with satisfactory recoveries (81.2-118.3%) and high precisions (RSDs <8.2, n = 3). Combining the optical properties of the nanohybrids, PCN-221(Zr/Ce)@Eu-DPA-H4btec integrated fluorescent hydrogels were innovatively prepared for visual sensing of SM2, SMR, and SMD. This study provides an uncomplicated and sensitive method for SAs detection in food matrices.

Thermochemistry of Solid-state Formation, Structure, Optical, and Luminescent Properties of Complex Oxides Eu2MeO6 (Me - Mo, W), Eu2W2O9: A Combined Experimental and DFT Study.

Complex oxides Eu2MeO6 (Me - Mo, W), Eu2W2O9 were obtained by a solid-phase reaction between binary oxides. The thermodynamic and kinetic mechanisms of the reaction processes were established using a variety of physical-chemical methods. All compounds obtained in this work crystallize in the low-symmetry monoclinic system, forming complex framework structures, which determine a set of very valuable physical-chemical properties. Comparison of experimental Kubelka-Munk functions and DFT- calculated absorption spectra shows adequate agreement and reveals the origin of the fundamental absorption. In addition, the deficiency in DFT calculations in the part of mutual contribution of CTBs of Mo-O and W-O, from one side, and Eu-O contributions, from the other side, is reported. Calculations of absorption spectra are shown to be superior to band structure analysis in the determination of optical band gaps. Additionally, luminescent properties of Eu2MeO6 and Eu2W2O9 compounds were investigated. These studies provide a better understanding of the electronic and optical properties of the compounds Eu2MeO6 and Eu2W2O9, along with their potential applications in various areas.

Site occupancy and tunable luminescence of Eu2+ and Eu3+ coactivated KCaY (PO4)2:Eu phosphors.

Utilizing the structure characteristic of KCaY (PO4)2 crystal, the site distribution of Eu2+ in KCaY (PO4)2:Eu phosphor coactivated with Eu2+ and Eu3+ ions is tuned. Upon 393-nm excitation, the as-prepared phosphor exhibits a broadband emission of Eu2+ peaked at ~ 475 nm and a typical red emission of Eu3+ with a strong 5D0-7F1 emission at ~ 591 nm. The luminescence color of the phosphor can be adjusted from blue to green, white, yellow, and red. The increasing concentration of Sr2+ and Eu2+ results in a blue shifting of Eu2+ emission. The increasing concentration of Eu3+ results in a red shifting of Eu2+ emission and an enhanced red emission of Eu3+. The luminescence behaviors of the phosphors are analyzed in terms of the site distribution of Eu2+ and Eu3+. A single-phase white light emitting was achieved in KCaY (PO4)2:Eu phosphor upon UV and NUV light excitation, indicating that the phosphor has potential application in white lighting.

Effect of the Addition of WO3 on the Structure and Luminescent Properties of ZnO-B2O3:Eu3+ Glass.

Glasses with the compositions in mol % of 50ZnO:(50 - x)B2O3:0.5Eu2O3:xWO3, x = 0, 1, 3, 5 and 10 were obtained by applying the melt-quenching method and investigated by Raman spectroscopy, DSC analysis and photoluminescence (PL) spectroscopy. Raman spectra revealed that tungstate ions incorporate into the base zinc borate glass as tetrahedral [WO4]2- groups, and octahedral [WØ4O2]2- species with four bridging and two non-bridging oxygen atoms. There are also metaborate, [BØ2O]- and pyroborate units, [B2O5]4-, in the glass networks. The glasses are characterized by good transmission in the visible region, at about 80%. Photoluminescence (PL) spectra evidenced that WO3 is an appropriate constituent for the modification of zinc borate glass structure and for enhancing the Eu3+ luminescent intensity. The most intense luminescence peak observed, at 612 nm, suggests that the glasses are potential materials for red emission.

Europium insertion into MgAl hydrotalcite-like compound to promote the photocatalytic oxidation of nitrogen oxides.

Easy synthesis of efficient, non-toxic photocatalysts is a target to expand their potential applications. In this research, the role of Eu3+ doping in the non-toxic, affordable, and easily prepared MgAl hydrotalcite-like compounds (HTlcs) was explored in order to prepare visible light semiconductors. Eu doped MgAl-HTlcs (MA-xEu) samples were prepared using a simple coprecipitation method (water, room temperature and atmospheric pressure) and europium was successfully incorporated into MgAl HTlc frameworks at various concentrations, with x (Eu3+/M3+ percentage) ranging from 2 to 15. Due to the higher ionic radius and lower polarizability of Eu3+ cation, its presence in the metal hydroxide layer induces slight structural distortions, which eventually affect the growth of the particles. The specific surface area also increases with the Eu content. Moreover, the presence of Eu3+ 4f energy levels in the electronic structure enables the absorption of visible light in the doped MA-xEu samples and contributes to efficient electron-hole separation. The microstructural and electronic changes induced by the insertion of Eu enable the preparation of visible light MgAl-based HTlcs photocatalysts for air purification purposes. Specifically, the optimal HTlc photocatalyst showed improved NOx removal efficiency, ∼ 51% (UV-Vis) and 39% (visible light irradiation, 420 nm), with excellent selectivity (> 96 %), stability (> 7 h), and enhanced release of •O2- radicals. Such results demonstrate a simple way to design photocatalytic HTlcs suitable for air purification technologies.

Integrated Eu3+ loaded covalent organic framework with smartphone for ratiometric fluorescence detection of tetracycline.

Developing rapid tetracycline sensing system is of great significance to monitor the illegal addition to drugs and pollution to food and ecosystem. By loading covalent organic frameworks (COFs) with Eu3+, a new hybridized material (COF@Eu3+) was prepared for tetracycline determination. Based on the Schiff base reaction, the COFs were by synthesized through solvent evaporation in 30 min at room temperature. Thereafter, Eu3+ was modified into COFs to develop the COF@Eu3+ sensing platform by adsorption and coordination. In presence of tetracycline, tetracycline can displace water molecules and coordinate with Eu3+ through the antenna effect. As a result, the red fluorescence of Eu3+ was enhanced by tetracycline with green fluorescence of COF as a reference. The developed ratiometric fluorescence sensor exhibits a linear range of 0.1-20 µM for detecting tetracycline with a detection limit of 30 nM. Integrated with a smartphone, the rapid tetracycline detection can be realized in situ, which is potential for high-throughput screening of tetracycline contaminated samples. Furthermore, the COF@Eu3+ fluorescence sensor has been successfully applied to the detection of tetracycline in traditional Chinese medicine compound preparation with satisfied recoveries. Therefore, a smartphone-assisted device was successfully developed based on Eu3+-functionalized COF, which is an attractive candidate for further applications of fluorescence sensing and visual detection.

Colour tunable photoluminescence studies of Dy3+/Eu3+ co-doped BaPbAlFB glasses for epoxy-free w-LED applications.

Barium lead alumino fluoroborate (BaPbAlFB) glasses singly and co-doped with Dy3+ and Eu3+ ions were prepared by melt quench method and studied their photoluminescence (PL) properties along with energy migration. Singly doped Dy3+/Eu3+ ions in BaPbAlFB glasses under 365 and 393 nm excitation wavelengths emit the PL bands through Dy: (4F9/2 → 6H15/2 and 4F9/2 → 6H13/2) and Eu: (5D0→7F2) transitions located at (Dy: 483 and 575 nm) and (Eu: 613 nm) respectively. Further, tunability of PL emissions is achieved by exciting the Dy3+/Eu3+ co-doped BaPbAlFB glasses at various wavelengths. The obtained CIE (0.34, 0.33) and CCT value (5080.4 K) of Dy3+/Eu3+ co-doped BaPbAlFB glass produced white light emission under 365 nm excitation wavelength. The corresponding CCT values of Dy3+/Eu3+ co-doped BaPbAlFB glasses varied from 1580 to 5080 K and their corresponding color emission changes from intense red to white light regime quite suitable for fabrication of epoxy-free w-LED devices.

A dual-response ratiometric fluorescent sensor for oxytetracycline determination in milk and mutton samples.

Owing to the adverse effects of oxytetracycline (OTC) residues on human health, it is of great importance to construct a rapid and effective strategy for OTC detection. Herein, we developed a dual-response fluorescence sensing platform based on molybdenum sulfide quantum dots (MoS2 QDs) and europium ions (Eu3+) for ratiometric detection of OTC. The MoS2 QDs, synthesized through an uncomplicated one-step hydrothermal approach, upon OTC integration into the MoS2 QDs/Eu3+ sensing system, exhibit a significant quenching of blue fluorescence due to the inner filter effect (IFE), simultaneously enhancing the distinct red emission of Eu3+ at 624 nm, a phenomenon attributed to the antenna effect (AE). This sensor demonstrates exceptional selectivity and sensitivity towards OTC, characterized by a linear detection range of 0.2-10 µM and a notably low detection limit of 2.21 nM. Furthermore, we achieved a visual semi-quantitative assessment of OTC through the discernible fluorescence color transition from blue to red under a 365 nm ultraviolet lamp. The practical applicability of this sensor was validated through the successful detection of OTC in milk and mutton samples, underscoring its potential as a robust tool for OTC monitoring in foodstuffs to safeguard food safety.

Epifluorescence microscopy study of a quadruple node of triple junctions of grain boundaries in a Eu2+-decorated highly textured composite of (Cl, Br)(K, Rb) and I(K, Rb) solid solutions.

The structural nature and geometry, as well as the lattice-relative orientation, of an arrangement of crystal defects in a highly textured Eu2+-doped composite of two alkali-halide solid solutions was studied by epifluorescence microscopy (EFM) using the doping ion as a fluorochrome. A three-dimensional reconstruction and a skeleton type model, as built from a sequence of EFM images of different optical cross-sections of this arrangement, are presented. Structurally, this arrangement is a quadruple node (QN) of triple junctions of grain boundaries. The QN core geometry is that of a tetragonal tristetrahedron (TTTH), centred at the QN site, whose tetrahedron vertices and edges are on the QN triple junctions and grain boundaries, respectively, whereas the tristetrahedron tetragonal axis is nearly parallel to the lattice [001]-axis. The measured values of the angles between triple junctions and between the grain boundaries forming them are reported. The distinct chemical compositions of the composite solid solutions are discussed to be responsible, in last instance, for the tristetrahedron departure from a cubic configuration. Collaterally, certain families of translationally periodic almost-parallel (TPAP)-wall-like regions which consist of TPAP-columns of TPAP-spindle-like singularities, as well as certain zigzag arrays of columns of this like, existing into the QN grains, are reported to be observed. Three-dimensional reconstructions of typical individuals of these families and arrays as well as of their constituent parts are presented and geometrically analysed. These families and arrays are discussed to be families of tilt subboundaries, whose constituent dislocations are decorated by cylindrical second-phase europium di-halide precipitates, and regularly faceted tilt subboundaries, respectively. Crystal growing and sample preparation, composite structural characterisation by powder and single-slab X-ray diffraction (PXRD and SSXRD, respectively), microscopy and fluorescence-cube unit optics, image processing, electronic three-dimensional reconstruction and measuring methodologies, are all described in detail.

Elucidating the Mechanism of Efficient Eu(III) and Yb(III) Sensitisation from a Re(I) Tetrazolato Triangular Assembly.

The reaction of Re(CO)5Br with deprotonated 1H-(5-(2,2':6',2''-terpyridine)pyrid-2-yl)tetrazole yields a triangular assembly formed by tricarbonyl Re(I) vertices. Photophysical measurements reveal blue-green emission with a maximum at 520 nm, 32% quantum yield, and 2430 ns long-lived excited state decay lifetime in deaerated dichloromethane solution. Coordination of lanthanoid ions to the terpyridine units red-shifts the emission to 570 nm and also reveals efficient (90%) and fast sensitisation to both Eu(III) and Yb(III) at room temperature, with a similar rate constant kET of the order of 107 s-1. Efficient sensitisation of Eu(III) from Re(I) is unprecedented, especially when considering the close proximity in energy between the donor and acceptor excited states. On the other hand, comparative measurements at 77 K reveal that energy transfer to Yb(III) is two orders of magnitude slower than that to Eu(III). A two-step mechanism of sensitisation is therefore proposed, whereby the rate-determining step is a thermally activated energy transfer step between the Re(I) centre and the terpyridine functionality, followed by rapid energy transfer to the respective Ln(III) excited states. At 77 K, the direct Re(I) to Eu(III) energy transfer seems to proceed via a ligand-mediated superexchange Dexter-type mechanism.

Synthesis and evaluation of fluorescent resins with europium-ß-diketonate complex for orthodontic use.

No effective technique exists for removing adhesive remnants following bracket debonding. We propose that fluorescence imaging using europium ions (Eu3+) offers an effective solution for minimizing iatrogenic enamel damage. This study aimed to assess the impact of different mixing ratios of monomer mixtures on the photoluminescence and flexural properties of a newly developed fluorescent adhesive. Four monomer blends with varying urethane dimethacrylate (UDMA) to triethylene glycol dimethacrylate (TEGDMA) ratios were prepared and polymerized. The blends contained 0.1 wt% of tris(1,3-diphenyl-1,3-propanedionato)(1,10-phenanthroline) Eu(III), [Eu(DBM)3Phen], as the phosphor. Optical measurements and flexural tests were conducted for each resin specimen. The emission spectra exhibited narrow bands corresponding to the 4f-4f transitions of the Eu3+ ions. The photoluminescence properties remained unaffected by the mixing ratio, whereas the mechanical properties tended to improve with higher UDMA content. We conclude that the Eu(DBM)3Phen-containing resin shows promise as a fluorescent orthodontic adhesive that contributes to preserving enamel health.

A reliable fluorescence "turn-on" aptasensor based on dual-emitting europium metal-organic frameworks for ultrasensitive and selective detection of sulfamethazine.

A high-performance fluorescent "turn-on" aptasensor (Eu-MOFs@SMZ-Apt) for sulfamethazine (SMZ) determination was designed using dual-emitting europium metal-organic frameworks (Eu-MOFs) as a signal transducer and an amplifier. Eu-MOFs featuring dual emission peaks (430 nm and 620 nm) were first prepared via a facile self-assembly strategy employing Eu (III) ions and 2-aminoterephthalic acid as precursors. The high-affinity aptamer was bonded with Eu-MOFs to form Eu-MOFs@SMZ-Apt through the amidation reaction. Benefiting from the integration of inherent virtues from Eu-MOFs and aptamer, the Eu-MOFs@SMZ-Apt-based sensor allowed sensitive and selective determination of SMZ with good linear relationships in a range of 1.4-40 ng mL-1 and a low detection line (0.379 ng mL-1). This sensor was successfully applied to the determination of trace SMZ in real samples with satisfactory recoveries (86.47-113.52%) and a relative standard deviation (<6.51). Consequently, the Eu-MOFs@SMZ-Apt ratiometric fluorescence sensor furnishes new possibilities for the accurate detection of various pollutants in food.

Chiral Tetrakis Eu(III) Complexes with Ammonium Cations for Improved Circularly Polarized Luminescence.

Large dissymmetry factor of the circularly polarized luminescence (gCPL) was observed in ligand and coordination tuned chiral tetrakis europium (Eu(III)) complexes with ammonium cations. The gCPL value was estimated to be -1.54, which is the largest among chiral luminescent molecules. Through photophysical measurements, single crystal X-ray structural analyses and quantum chemical calculations, changes in the geometric and electronic structures were observed for a series of chiral tetrakis Eu(III) complexes which enhanced the gCPL value. The emission quantum yield and photosensitized energy transfer efficiencies of chiral Eu(III) complexes with ammonium cations were also larger than those of chiral Eu(III) complex with Cs+. Based on the systematic modifications and analyses for chiral tetrakis Eu(III) complex, effect of the ammonium cation on enhanced CPL brightness is reported.

Cellular Response of Adapted and Non-Adapted Tetrahymena thermophila Strains to Europium Eu(III) Compounds.

Europium is one of the most reactive lanthanides and humans use it in many different applications, but we still know little about its potential toxicity and cellular response to its exposure. Two strains of the eukaryotic microorganism model Tetrahymena thermophila were adapted to high concentrations of two Eu(III) compounds (EuCl3 or Eu2O3) and compared to a control strain and cultures treated with both compounds. In this ciliate, EuCl3 is more toxic than Eu2O3. LC50 values show that this microorganism is more resistant to these Eu(III) compounds than other microorganisms. Oxidative stress originated mainly by Eu2O3 is minimized by overexpression of genes encoding important antioxidant enzymes. The overexpression of metallothionein genes under treatment with Eu(III) compounds supports the possibility that this lanthanide may interact with the -SH groups of the cysteine residues from metallothioneins and/or displace essential cations of these proteins during their homeostatic function. Both lipid metabolism (lipid droplets fusing with europium-containing vacuoles) and autophagy are involved in the cellular response to europium stress. Bioaccumulation, together with a possible biomineralization to europium phosphate, seems to be the main mechanism of Eu(III) detoxification in these cells.

Green Synthesis and the Evaluation of Osteogenic Potential of Novel Europium-Doped-Monetite Calcium Phosphate by Cissus quadrangularis.

Background The quest for an ideal bone grafting material has been ongoing for decades. Calcium phosphate, alone or in combination with other materials in natural bone, has been shown to aid in bone regeneration effectively. Monetite exhibits superior solubility and resorption rates among calcium phosphates, rendering it an optimal choice for bone regeneration applications. However, the degradation rate of the Monetite is much faster than that of all the other calcium phosphates. Hence, we have added Europium onto the matrix to alter the degradation profile and enhance the osteogenic ability of the prepared matrix. Materials and methods An exclusive Europium-Monetite composite was synthesized employing eco-friendly techniques involving Cissus quadrangularis. The osteogenic potential was gauged using the MG-63 cell line through a calcium mineralization assay employing an Alizarin Red solution, collagen estimation, and an alkaline phosphatase (ALP) assay. The composite's cytocompatibility was evaluated using the MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay across different concentrations ranging from 12.5 µg to 100 µg. Results Scanning electron microscopy (SEM) analysis of the Europium-Monetite composite revealed a sheet-like arrangement in stacks, and the ATR-IR confirmed the presence of elements Ca, P, and Eu. The osteogenic potential, analyzed by ALP activity, calcium mineralization, and collagen staining, was 10% higher than that of the control (Monetite).  Conclusion The prepared novel Europium-Monetite calcium phosphate complex can enhance the osteogenic potential and could be a promising material for bone regeneration/tissue engineering. The newly created Europium-Monetite calcium phosphate complex holds promise for various bone grafting applications, including integration into scaffolds and as a coating for implants.