Demystification of luminescence properties and the near imperceptible thermal quenching of Sm3+-doped tungstate phosphors.

Ultra-high thermally stable Ca2MgWO6:xSm3+ (x = 0.5, 0.75, 1, 1.25, and 1.5 mol%) double perovskite phosphors were synthesized through solid-state reaction method. Product formation was confirmed by comparing the X-ray diffraction (XRD) patterns of the phosphors with the standard reference file. The structural, morphological, thermal, and optical properties of the prepared phosphor were examined in detail using XRD, Fourier transform infrared spectra, scanning electron microscopy, diffused reflectance spectra, thermogravimetric analysis (TGA), photoluminescence emission, and temperature-dependent PLE (TDPL). It was seen that the phosphor exhibited emission in the reddish region for the near-ultraviolet excitation with moderate Colour Rendering Index values and high colour purity. The optimized phosphor (x = 1.25 mol%) was found to possess a direct optical band gap of 3.31 eV. TGA studies showed the astonishing thermal stability of the optimized phosphor. Additionally, near-zero thermal quenching was seen in TDPL due to elevated phonon-assisted radiative transition. Furthermore, the anti-Stokes and Stokes emission peaks were found to be sensitive toward the temperature change and followed a Boltzmann-type distribution. All these marked properties will make the prepared phosphors a suitable candidate for multifield applications and a fascinating material for further development.

Lanthanide Inorganic Nanoparticles Enhance Semiconducting Polymer Nanoparticles Afterglow Luminescence for In Vivo Afterglow/Magnetic Resonance Imaging.

Dual/multimodal imaging strategies are increasingly recognized for their potential to provide comprehensive diagnostic insights in cancer imaging by harnessing complementary data. This study presents an innovative probe that capitalizes on the synergistic benefits of afterglow luminescence and magnetic resonance imaging (MRI), effectively eliminating autofluorescence interference and delivering a superior signal-to-noise ratio. Additionally, it facilitates deep tissue penetration and enables noninvasive imaging. Despite the advantages, only a limited number of probes have demonstrated the capability to simultaneously enhance afterglow luminescence and achieve high-resolution MRI and afterglow imaging. Herein, we introduce a cutting-edge imaging platform based on semiconducting polymer nanoparticles (PFODBT) integrated with NaYF4@NaGdF4 (Y@Gd@PFO-SPNs), which can directly amplify afterglow luminescence and generate MRI and afterglow signals in tumor tissues. The proposed mechanism involves lanthanide nanoparticles producing singlet oxygen (1O2) upon white light irradiation, which subsequently oxidizes PFODBT, thereby intensifying afterglow luminescence. This innovative platform paves the way for the development of high signal-to-background ratio imaging modalities, promising noninvasive diagnostics for cancer.

Finely-Tuning Chemiluminescent Color of CdTe Nanocrystals and Its Application for Near-Infrared Semi-Automatic Immunoassay.

Chemiluminescence (CL), especially commercialized CL immunoassay (CLIA), is normally performed within the eye-visible region of the spectrum by exploiting the electronic-transition-related emission of the molecule luminophore. Herein, dual-stabilizers-capped CdTe nanocrystals (NCs) is employed as a model of nanoparticulated luminophore to finely tune the CL color with superior color purity. Initialized by oxidizing the CdTe NCs with potassium periodate (KIO4), intermediates of the reactive oxygen species (ROS) tend to charge CdTe NCs in both series-connection and parallel-connection routes and dominate the charge-transfer CL of CdTe NCs. The CdTe NCs/KIO4 system can exhibit color-tunable CL with the maximum emission wavelength shifted from 694 nm to 801 nm, and the red-shift span is over 100 nm. Both PL and CL of each of the CdTe NCs are bandgap-engineered; the change in the NCs surface state via CL reaction enables CL of each of the CdTe NCs to be red-shifted for ∼20 nm to PL, while the change in the NCs surface state via labeling CdTe NCs to secondary-antibody (Ab2) enables CL of the CdTe NCs-Ab2 conjugates to be red-shifted for another ∼20 nm to bare CdTe NCs. The CL of CdTe753-Ab2/KIO4 is ∼791 nm, which can perform near-infrared CL immunoassay and semi-automatically determined procalcitonin (PCT) on commercialized in vitro diagnosis (IVD) instruments.

The influence of solvent refractive index on the photoluminescence decay of thick-shell gradient-alloyed colloidal quantum dots investigated in a wide range of delay times.

Colloidal semiconductor quantum dots have many potential optical applications, including quantum dot light-emitting diodes, single-photon sources, or biological luminescent markers. The optical properties of colloidal quantum dots can be affected by their dielectric environment. This study investigated the photoluminescence (PL) decay of thick-shell gradient-alloyed colloidal semiconductor quantum dots as a function of solvent refractive index. These measurements were conducted in a wide range of delay times to account for both the initial spontaneous decay of excitons and the delayed emission of excitons that has the form of a power law. It is shown that whereas the initial spontaneous PL decay is very sensitive to the refractive index of the solvent, the power-law delayed emission of excitons is not. Our results seem to exclude the possibility of carrier self-trapping in the considered solvents and suggest the existence of trap states inside the quantum dots. Finally, our data show that the average exciton lifetime significantly decreases as a function of the solvent refractive index. The change in exciton lifetime is qualitatively modeled and discussed.

Fe3+-activated magnetoplumbite persistent luminescence phosphor by modulating the oxygen vacancy.

Broadband near-infrared (NIR) spectroscopy has gained significant attention due to its versatile application in various fields. In the realm of NIR phosphors, Fe3+ ion is an excellent activator known for its nontoxic and harmless nature. In this study, we prepared an Fe3+-activated SrGa12O19 (SGO) NIR phosphor and analyzed its phase and luminescence properties. Upon excitation at 326 nm, the SGO:Fe3+ phosphor exhibited a broadband emission in the range 700-1000 nm, peaking at 816 nm. The optical band gap of SGO:Fe3+ was evaluated. To enhance the long-lasting phosphorescence, an oxygen vacancy-rich SGO:Fe3+ (VO-SGO:Fe3+) sample was prepared for activation. Interestingly, the increase in the oxygen-vacancy concentration indeed contributed to the activation of persistent luminescence of Fe3+ ions. The VO-SGO:Fe3+ sample has a long duration and high charge storage capacity, allowing it to perform efficiently in various applications. This work provides the foundation for further design of Cr3+-free PersL phosphors with efficient NIR PersL.

Graphene nanosheet reinforcement of polyurethane nanocomposite for green and sustainable photoluminescence, superhydrophobic, and anticorrosive paint.

A simple and environmentally friendly method was developed for smart and efficient waterborne polyurethane (PUR) paint. Sugarcane bagasse was recycled into reduced graphene oxide nanosheets (rGONSs). Both lanthanide-doped aluminate nanoparticles (LAN; photoluminescent agent, 7-9 nm) and rGONSs (reinforcement agent) were integrated into a waterborne polyurethane to produce a novel photoluminescent, hydrophobic, and anticorrosive nanocomposite coating. Using ferrocene-based oxidation under masked circumstances, graphene oxide nanosheets were produced from sugarcane bagasse. The oxidized semicarbazide (SCB) nanostructures were integrated into polyurethane coatings as a drying, anticorrosion, and crosslinking agent. Polyurethane coatings with varying amounts of phosphor pigment were prepared and subsequently applied to mild steel. The produced paints (LAN/rGONSs@PUR) were tested for their hydrophobicity, hardness, and scratch resistance. Commission Internationale de l'éclairage (CIE) Laboratory parameters and photoluminescence analysis established the opacity and colourimetric properties of the nanocomposite coatings. When excited at 365 nm, the luminescent transparent paints emitted a strong greenish light at 517 nm. The anticorrosion characteristics of the coated steel were investigated. The phosphor-containing (11% w/w) polyurethane coatings displayed the most pronounced anticorrosion capability and long-persistent luminosity. The prepared waterborne polyurethane paints were very photostable and durable.

Enhanced photocatalytic and electrochemical performance of hydrothermally prepared NiO-doped Co nanocomposites.

In this study, we synthesize nanostructured nickel oxide (NiO) and doped cobalt (Co) by combining nickel(II) chloride hexahydrate (NiCl2.6H2O) and sodium hydroxide (NaOH) as initial substances. We analyzed the characteristics of the product nanostructures, including their structure, optical properties, and magnetic properties, using various techniques such as x-ray diffraction (XRD), scanning electron microscopy (SEM), ultraviolet absorption spectroscopy (UV-Vis), Fourier transform infrared (FTIR) spectroscopy, and vibrating sample magnetometers (VSM). The NiO nanoparticles doped with Co showed photocatalytic activity in degrading methylene blue (MB) dye in aqueous solutions. We calculated the degradation efficiencies by analyzing the UV-Vis absorption spectra at the dye's absorption wavelength of 664 nm. It was observed that the NiO-doped Co nanoparticles facilitated enhanced recombination and migration of active elements, which led to more effective degradation of organic dyes during photocatalysis. We also assessed the electrochemical properties of the materials using cyclic voltammetry (CV) and impedance spectroscopy in a 1 mol% NaOH solution. The NiO-modified electrode exhibited poor voltammogram performance due to insufficient contact between nanoparticles and the electrolyte solution. In contrast, the uncapped NiO's oxidation and reduction cyclic voltammograms displayed redox peaks at 0.36 and 0.30 V, respectively.

Exploring the Light-Emitting Agents in Renilla Luciferases by an Effective QM/MM Approach.

Bioluminescence is a fascinating natural phenomenon, wherein organisms produce light through specific biochemical reactions. Among these organisms, Renilla luciferase (RLuc) derived from the sea pansy Renilla reniformis is notable for its blue light emission and has potential applications in bioluminescent tagging. Our study focuses on RLuc8, a variant of RLuc with eight amino acid substitutions. Recent studies have shown that the luminescent emitter coelenteramide can adopt multiple protonation states, which may be influenced by nearby residues at the enzyme's active site, demonstrating a complex interplay between protein structure and bioluminescence. Herein, using the quantum mechanical consistent force field method and the semimacroscopic protein dipole-Langevin dipole method with linear response approximation, we show that the phenolate state of coelenteramide in RLuc8 is the primary light-emitting species in agreement with experimental results. Our calculations also suggest that the proton transfer (PT) from neutral coelenteramide to Asp162 plays a crucial role in the bioluminescence process. Additionally, we reproduced the observed emission maximum for the amide anion in RLuc8-D120A and the pyrazine anion in the presence of a Na+ counterion in RLuc8-D162A, suggesting that these are the primary emitters. Furthermore, our calculations on the neutral emitter in the engineered AncFT-D160A enzyme, structurally akin to RLuc8-D162A but with a considerably blue-shifted emission peak, aligned with the observed data, possibly explaining the variance in emission peaks. Overall, this study demonstrates an effective approach to investigate chromophores' bimolecular states while incorporating the PT process in emission spectra calculations, contributing valuable insights for future studies of PT in photoproteins.

Laponite-activated AIE supramolecular assembly with modulating multicolor luminescence for logic digital encryption and perfluorinated pollutant detection.

Recently, the non-covalently activated supramolecular scaffold method has become a prominent research area in the field of intelligent materials. Here, the inorganic clay (LP) promoted the AIE properties of 4,4',4″,4‴-(ethene-1,1,2,2-tetrayltetrakis(benzene-4,1-diyl))tetrakis(1-ethylpyridin-1-ium) (P-TPE), showing an astonishing 42-fold enhancement of the emission intensity of the yellow-green luminescence and a 34-fold increase of the quantum yield via organic-inorganic supramolecular strategy as well as the efficient light-harvesting properties (energy transfer efficiency up to 33 %) after doping with the dye receptor Rhodamine B. Furthermore, the full-color spectral regulation, including white light, was achieved by adjusting the ratio of the donor to the acceptor component and co-assembling with the carbon dots (CD). Interestingly, this TPE-based non-covalently activated full-color supramolecular light-harvesting system (LHS) could be achieved not only in aqueous media but also in the hydrogel and the solid state. More importantly, this panchromatic tunable supramolecular LHS exhibited the multi-mode and quadruple digital logic encryption property as well as the specific detection ability towards the perfluorobutyric acid and the perfluorobutanesulfonic acid, which are harmful to human health in drinking water. This result develops a simple, convenient and effective approach for the intelligent anti-counterfeiting and the pollutant sensing.

Two-Photon Nanoparticle Probe for Formaldehyde Detection via the AILE Luminescence Mechanism.

A two-photon nanoparticle probe was designed and developed based on the principle of intermolecular interaction of the aggregation-induced locally excited emission luminescence mechanism. The probe has the advantages of simple synthesis, convenient use, strong atomic economy, good biocompatibility, and photobleaching resistance. It can produce a specific and sensitive response to formaldehyde, help detect FA in normal cells and cancer cells, and is expected to become a specific detection probe for FA in vitro and in vivo.

Effect of IRSL-BLSL-TSL reading modes combination on thermoluminescence (TL) response of BeO dosimeter.

The ultimate goal of this work is the study of the effect of luminescence stimulations and signals reading modes combinations on the thermoluminescence intensity and glow curve behaviour for the same X-ray irradiation dose. Three interesting stimulating and reading modes are considered, namely, infrared stimulated luminescence (IRSL), blue light-emitting diode stimulated luminescence (BLSL) and thermally stimulated luminescence (TSL). The studied stimulation and reading modes combination protocols are (Protocol 1) IRSL-TSL, (Protocol 2) IRSL-BLSL-TSL and (Protocol 3) BLSL-IRSL-TSL. Experiments are performed on beryllium oxide (BeO) dosimeter. Results demonstrate well that the combination of reading modes have direct impact on the TL signal in terms of intensity and glow curve shape. It was also found that when reading modes are correctly combined, particularly when IRSL is applied first, then BLSL and TL, it is possible to collect two or more exploitable signals of different stimulation types for the same irradiation that can be used for different purposes and final applications.

Orange luminescence of α-Al2O3 related to clusters consisting of F centers and divalent cations.

The orange luminescence of α-Al2O3 under UV excitation is characterized by a 2.07-eV orange broadband emission that has not yet been elucidated. This emission is present in natural and synthetic crystals and powders, as well as in Be-treated samples. All orange-luminescent materials have low Fe concentration (mostly <1000 ppm) with traces of divalent cations, mostly Mg, or Be in Be-diffused material (dozens of ppm). Mg2+, Mn2+, and Be2+ cations substitute for trivalent Al. To accommodate the charge deficit, several defects are created, including oxygen vacancies also called F centers. Indeed, our excitation spectra revealed the presence of several different F centers (F, F+, and clustered F2, F2 +, F2 2+) in those samples. However, the thermal stability and the measured luminescence lifetimes do not match with previously reported characteristics of isolated F centers. Based on our experiments, we suggest that a complex aggregate of two F centers (F2 2+) trapped at divalent cations is a major cause of this uncommon microsecond lifetime emission, even if a variety of other defects, including Cr3+, V3+, or interstitial Al3+, are present.

Quantitative analysis of CL-20 explosive by smartphone-based chemiluminescence method.

A new smartphone-based chemiluminescence method has been introduced for the quantitative analysis of CL-20 (Hexanitroazaisowuertzitan) explosive. The solvent mixture, oxidizer agent, and concentration of the reactants were optimized using statistical procedures. CL-20 explosive showed a quenching effect on the chemiluminescence intensity of the luminol-NaClO reaction in the solvent mixture of DMSO/H2O. A smartphone was used as a detector to record the light intensity of chemiluminescence reaction as a video file. The recorded video file was converted to an analytical signal as intensity luminescence-time curve by a written code in MATLAB software. Dynamic range and limit of detection of the proposed method were obtained 2.0-240.0 and 1.1 mg⋅L-1, respectively, in optimized concentrations 1.5 × 10-3 mol⋅L-1 luminol and 1.0 × 10-2 mol⋅L-1 NaClO. Precursors TADB, HBIW, and TADNIW in CL-20 explosive synthesis did not show interference in measurement the CL-20 purity. The analysis of CL-20 spiked samples of soil and water indicated the satisfactory ability of the method in the analysis of real samples. The interaction of CL-20 molecules and OCl- ions is due to quench of chemiluminescence reaction of the luminol-NaClO.

Similar enzymatic functions in distinct bioluminescence systems: evolutionary recruitment of sulfotransferases in ostracod light organs.

Genes from ancient families are sometimes involved in the convergent evolutionary origins of similar traits, even across vast phylogenetic distances. Sulfotransferases are an ancient family of enzymes that transfer sulfate from a donor to a wide variety of substrates, including probable roles in some bioluminescence systems. Here, we demonstrate multiple sulfotransferases, highly expressed in light organs of the bioluminescent ostracod Vargula tsujii, transfer sulfate in vitro to the luciferin substrate, vargulin. We find luciferin sulfotransferases (LSTs) of ostracods are not orthologous to known LSTs of fireflies or sea pansies; animals with distinct and convergently evolved bioluminescence systems compared to ostracods. Therefore, distantly related sulfotransferases were independently recruited at least three times, leading to parallel evolution of luciferin metabolism in three highly diverged organisms. Reuse of homologous genes is surprising in these bioluminescence systems because the other components, including luciferins and luciferases, are completely distinct. Whether convergently evolved traits incorporate ancient genes with similar functions or instead use distinct, often newer, genes may be constrained by how many genetic solutions exist for a particular function. When fewer solutions exist, as in genetic sulfation of small molecules, evolution may be more constrained to use the same genes time and again.

Synthesis and study of optical properties of a Gd3+-doped NaYF4 phosphor for phototherapy lamp application.

In recent trends, radiation falls under the narrowband ultraviolet-B region (305-315 nm) widely used in phototherapy lamp applications in the treatment of skin diseases. In this paper, we report a Gd3+-doped NaYF4 luminescent material synthesized for the first time using the low-temperature co-precipitation method. It crystallized into a face-centred cubic structure, as confirmed by X-ray diffraction characterization techniques and Rietveld refinement. The photoluminescence property of the as-prepared sample shows a highly intense, sharp emission band obtained at 311 nm, which belongs to the narrowband ultraviolet-B region and corresponds to the transition of the 6P7/2→8S7/2 level of the Gd3+ ions under 272 nm excitation (8S7/2 to 6IJ). The transitions of the Gd3+ ions are detected entirely with different concentrations of Gd3+ ions. Scanning electron microscopy analysis indicated that the average particle was 288 nm. The critical distance for energy transfer was calculated to be equal to 11.5017 Å. Dipole-dipole interaction is responsible for energy transfer, as analyzed by Dexter theory. These excellent optical characteristics, together with their highly efficient and low-cost synthesis approach, indicate that synthesized NaYF4:Gd3+ phosphors have excessive potential for phototherapeutic lamp applications.

Rapid room-temperature phosphorescence chiral recognition of natural amino acids.

Chiral recognition of amino acids is very important in both chemical and life sciences. Although chiral recognition with luminescence has many advantages such as being inexpensive, it is usually slow and lacks generality as the recognition module relies on structural complementarity. Here, we show that one single molecular-solid sensor, L-phenylalanine derived benzamide, can manifest the structural difference between the natural, left-handed amino acid and its right-handed counterpart via the difference of room-temperature phosphorescence (RTP) irrespective of the specific chemical structure. To realize rapid and reliable sensing, the doped samples are obtained as nanocrystals from evaporation of the tetrahydrofuran solutions, which allows for efficient triplet-triplet energy transfer to the chiral analytes generated in situ from chiral amino acids. The results show that L-analytes induce strong RTP, whereas the unnatural D-analytes produce barely any afterglow. The method expands the scope of luminescence chiral sensing by lessening the requirement for specific molecular structures.

Luminescence of Sm3+ in double perovskite-type Ba2SrWO6 for insect trapping.

The predominant method for pest control has been the use of pesticides, which have been shown to have detrimental effects on soil, freshwater, and crop quality. Therefore, the development of novel and sustainable crop protection strategies has become increasingly imperative. In this study, a novel orange-red emitting Ba2SrWO6: Sm3+ phosphor was synthesized using the high-temperature solid-state reaction. Under ultraviolet excitation, the phosphors showed obvious emission peaks at 575, 614, and 662 nm. The Ba2SrWO6: Sm3+ was used to fabricate a fluorescence film with polydimethylsiloxane (PDMS), and attracted twice as many insects as the blank control group under 365 nm ultraviolet light. This material holds great potential as a fluorescent agent for insect trapping in the pest control fields of tea, cotton, eggplant, rice, potato, grape, and other agricultural industries. Our findings provide an eco-friendly approach to pest management for the increment of food production.

Luminescence-Based Techniques for KRAS Thermal Stability Monitoring.

Various biochemical methods have been introduced to detect and characterize KRAS activity and interactions, from which the vast majority is based on luminescence detection in its varying forms. Among these methods, thermal stability assays, using luminophore-conjugated proteins or external environment sensing dyes, are widely used. In this chapter, we describe methods enabling KRAS stability monitoring in vitro, with an emphasis on ligand-induced stability. This chapter focuses mainly on luminescence-based techniques utilizing external dye molecules and fluorescence detection.

FeS2 nanosheets-luminol-O2 chemiluminescence method for determination of venlafaxine hydrochloride, imipramine hydrochloride, and cefazolin sodium.

This study introduces a novel chemiluminescence (CL) approach utilizing FeS2 nanosheets (NSs) catalyzed luminol-O2 CL reaction for the measurement of three pharmaceuticals, namely venlafaxine hydrochloride (VFX), imipramine hydrochloride (IPM), and cefazolin sodium (CEF). The CL method involved the phenomenon of quenching induced by the pharmaceuticals in the CL reaction. To achieve the most quenching efficacy of the pharmaceuticals in the CL reaction, the concentrations of reactants comprising luminol, NaOH, and FeS2 NSs were optimized accordingly. The calibration curves demonstrated exceptional linearity within the concentration range spanning from 4.00 × 10-7 to 1.00 × 10-3 mol L-1, 1.00 × 10-7 to 1.00 × 10-4 mol L-1, and 4.00 × 10-6 to 2.00 × 10-4 mol L-1 with detection limits (3σ) of 3.54 × 10-7, 1.08 × 10-8, and 2.63 × 10-6 mol L-1 for VFX, IPM, and CEF, respectively. This study synthesized FeS2 NSs using a facile hydrothermal approach, and then the synthesized FeS2 NSs were subjected to a comprehensive characterization using a range of spectroscopic methods. The proposed CL method was effective in measuring the aforementioned pharmaceuticals in pharmaceutical formulations as well as different water samples. The mechanism of the CL system has been elucidated.

Applicability of a Chemiluminescence Immunoassay to Screen Postmortem Bile Specimens and Its Agreement with Confirmation Analysis.

Bile has emerged as an alternative matrix for toxicological investigation of drugs in suspected forensic cases of overdose in adults and intoxications in children. Toxicological investigation consists in screening and, subsequently, confirming the result with specific techniques, such as liquid chromatography with tandem mass spectrometry (LC-MS/MS). As there is no screening test on the market to test postmortem bile specimens, the novelty of this study was in investigating the applicability of a chemiluminescence immunoassay, designed for other matrices and available on the market, on bile and validate its use, testing the agreement with LC-MS/MS analysis. Bile specimens were obtained from 25 forensic cases of suspected death from overdose and intoxication. Sample preparation for bile screening consists simply in centrifugation and dilution. Confirmation analysis allows simultaneous identification of 108 drugs and was validated on bile. Kappa analysis assessed a perfect agreement (0.81-1) between the assays for benzodiazepines, methadone, opiates, cocaine, oxycodone, cannabinoids, buprenorphine and pregabalin; a substantial agreement (0.41-0.6) was reported for barbiturates. No agreement was assessed for amphetamines, due to an abundance of putrefactive amines in postmortem specimens. In conclusion, this fast and easy immunoassay could be used for initial screening of bile specimens, identifying presence of drugs, except amphetamines, with reliability.