Upconversion Luminescence Research Articles

Fluorescence sensor array for highly sensitive pattern recognition of biothiols in food based on tricolor upconversion luminescence metal-organic frameworks

Fluorescence sensor array for highly sensitive pattern recognition of biothiols in food based on tricolor upconversion luminescence metal-organic frameworks

Photoelectric Interaction and Photochromic Mechanism of K0.5Na0.5NbO3 Ceramics.

Rare-earth materials are widely used in the optical field due to their rich energy-level structures, and if endowed with photoelectric response characteristics, they are expected to be applied to photoelectric multifunctional devices. In this paper, Ho3+- and Yb3+-codoped K0.5Na0.5NbO3 (KNN) ferroelectric ceramics are synthesized, and the up-conversion and down-conversion luminescence intensity as well as the decay degree after photochromism can be controlled by the content of Yb3+. Strong green luminescence visible to the naked eye is realized, and the maximum luminescence decay is more than 50%. 2 s of color change fully indicates that the ceramic has the characteristics of fast response photochromic, under the most efficient wavelength of 405 nm by changing the irradiation wavelength. By incorporating data from thermal and electrical stimulation experiments, a comprehensive photochromic mechanism diagram is constructed, where the photochromic properties are predominantly governed by defects. It is believed that this work will provide a theoretical basis for the design of high-performance photochromic ceramics.

Dye-to-Er3+ Direct Energy Transfer for Enhancing Up- and Down-conversion Luminescence in Sub-10 nm NaErF4.

Dye sensitization enhances the luminescence of lanthanide nanoparticles by improving light-harvesting. Typically, Yb3+ serves as an energy bridge but absorbs at a single transition, limiting dyes' options (λex > 700 nm) due to the spectral overlap requirement. In contrast, the emitter Er3+ spans energy levels from UV to NIR, making it ideal for multicolor excitation. We developed a strategy to directly sensitize Er3+ upconversion (UCL) and downconversion luminescence (DCL) by using cyanine dyes. Cy5 demonstrated the greatest enhancement, achieving a 1942-fold UCL and 70-fold DCL increase compared to nanoparticles alone (Er-NPs) under 980 nm excitation. Smaller Er-NPs exhibited brighter dye-sensitized luminescence due to enhanced interfacial energy transfer. A 2 nm inert shell produced the brightest UCL, while thicker shells improved DCL. Dye-sensitized Er3+ emissions at 2H11/2 (525 nm) and 2P3/2 (408 nm) enabled temperature monitoring with a maximum sensitivity (Sa) of 3.69%/K. This approach holds significant potential for optical temperature sensing and medical imaging.

Untypical tuneable emission activated by NIR radiation observed in gadolinium borate nanomaterials doped with Yb3+, Ho3+ and Ce3+ ions.

New luminescent nanoparticles with adjustable emission properties were synthesized via a hydrothermal method to investigate the effect of Ce3+ concentration on the tuneable emission properties of Yb3+/Ho3+ co-doped gadolinium borates. The synthesized samples' comprehensive structural and morphological analysis was conducted utilizing X-ray diffraction and transmission electron microscopy. To obtain highly crystalline nanoparticles GdBO3:Yb3+/Ho3+/Ce3+ characterized by intense and bright emission, they were annealed at 525°C and 925°C. Under the excitation of 972nm, the tunable yellow to green up-conversion (UC) emission was observed, while the Ce3+ concentration increased. This change correlated with a difference in the correlated color temperature from 4345K to 5442K, respectively. The untypical changes observed in the red-to-green (R/G) ratio, displaying a declining trend contrary to conventional expectations, allowed for the proposed mechanism for understanding their UC luminescence properties. The results obtained indicate that the Ce3+ doped GdBO3:Yb3+/Ho3+ nanoparticles demonstrate high application potential for anti-counterfeiting.

MiR‐21‐Trigged Precise Photodynamic Therapy Through a “Locking‐Unlocking‐Boosting” ROS Production Strategy

AbstractPhotodynamic therapy (PDT) stands out as a highly promising modality for tumor treatment, yet previous works have primarily centered around either boosting the production of reactive oxygen species (ROS) in tumor tissues or restricting it in normal tissues. The current challenge lies in the urgent need to achieve precise modulation of ROS production by simultaneously controlling both aspects. To achieve this goal, a precise PDT platform through a “locking‐unlocking‐boosting” ROS production strategy is presented, in which the generation of ROS is modulated by bidirectionally regulating the upconversion luminescence (UCL) of lanthanide‐doped nanoparticles (LnNPs), thus ROS production is “locked” in normal tissues but “boosted” in tumor tissues. In detail, by introducing an energy acceptor BHQ3, the UCL is initially quenched to prevent Chlorin e6 (Ce6) from generating ROS. However, under the tumor microenvironment with overexpressed miR‐21, LnNPs are sequestered from BHQ3 to “unlock” ROS generation and then assembled with QDs@B2, which functions as an antenna to sensitize LnNPs luminescence, to further “boost” ROS generation. With the assistance of spherical nucleic acids, this therapeutic agent effectively traverses the blood‐brain barrier (BBB), enabling efficient PDT for glioblastoma.

Optical temperature sensing and upconversion luminescence in Er3+/Yb3+ co-doped BNT ferroelectric ceramic

Optical temperature sensing and upconversion luminescence in Er3+/Yb3+ co-doped BNT ferroelectric ceramic

Up-conversion luminescence properties and temperature sensing of Er3+-Yb3+ doped silicate glass-ceramics

Up-conversion luminescence properties and temperature sensing of Er3+-Yb3+ doped silicate glass-ceramics

Chromatic tuning of upconversion emission upon dual infrared wavelength co-excitation in Er3+ doped Ba3Lu4O9 phosphor

Emission color change of the upconversion luminescence materials is often required for applications in optical anti-counterfeiting, laser lighting, and 3D displays. In this work, we developed a new route for chromatic tuning of upconversion emission upon two wavelength co-excitation by changing excitation power density. The proposed route was used for Er3+ single-doped Ba3Lu4O9 phosphor which was derived from a traditional solid-state reaction. The crystal structure of the obtained Ba3Lu4O9:Er3+ phosphor was characterized by X-ray diffraction and Rietveld refinement modeling. Under individual excitation of 980 or 1550 nm, it was found that the luminescence intensity ratio of red to green changes slightly with respectively increasing excitation power density (working current of the laser) of 980 or 1550 nm laser. However, upon both 980 and 1550 nm co-excitation at the same time and by adjusting the excitation power density of one laser amongst the two lasers, the luminescence intensity ratio of red to green changes greatly with increasing excitation power density. The change of luminescence intensity ratio of red to green implies the upconversion emission color tuning. The mechanism for the color tuning was discovered. It was found that with changing excitation power density the ratio of red to green changed greatly when the phosphor was irradiated by 980 and 1550 together, but the ratio of red to green changed slightly when the phosphor was irradiated individually by 980 or 1550. It is proved that it is feasible to turn color by the method of two infrared wavelengths excitation.

Optimization of upconversion luminescence performance and temperature sensing characteristics of Sr0.37Ba0.50Al2Si2O8:Ho3+, Yb3+ phosphors based on a cation substitution strategy

Optimization of upconversion luminescence performance and temperature sensing characteristics of Sr0.37Ba0.50Al2Si2O8:Ho3+, Yb3+ phosphors based on a cation substitution strategy

Composition of cardiac troponin release differs after marathon running and myocardial infarction

ObjectivesElevations of cardiac troponin T (cTnT) levels are common after strenuous exercise. We assessed whether the composition of cTnT release after marathon race differs from that of acute myocardial infarction (MI).MethodsTroponin composition was analysed in plasma samples taken from 45 runners after marathon race and from 84 patients with type 1 MI. The concentration of long cTnT (intact and mildly fragmented cTnT) was measured with a novel upconversion luminescence immunoassay, total cTnT with a commercial high-sensitivity cTnT assay, and the ratio of long to total cTnT (troponin ratio) was determined as a measure of troponin fragmentation.ResultsTotal cTnT exceeded the upper reference limit (>14 ng/L) in 37 (82%) runners. Troponin ratio was lower in runners ((IQR) 0.17 (0.11–0.24) vs 0.62 (0.29–0.96), p<0.001). With increasing troponin release the troponin ratio decreased (r=−0.497, p<0.001) in marathon runners and the concentration of long cTnT remained in all runners below 8.4 ng/L. In contrast to marathon runners, troponin ratio increased (r=0.565, p<0.001) with the increase of cTnT release in patients with MI. The median total and long cTnT concentrations were lower in marathon runners than in patients with MI (25 ng/L vs 835 ng/L and 4.1 vs 385 ng/L, p<0.001 for both).ConclusionIn contrast to type 1 MI, only a small fraction of circulating cTnT exists as intact cTnT or long molecular forms after strenuous exercise and the difference in troponin composition is more pronounced in runners with higher troponin release.Trial registration numberNCT06000930.

Calcination-assisted hydrothermal crystallization and comparative up-/down-conversion luminescence of RE3+ (RE=Ho, Er and Tm)-doped YbNbO4 and Yb3NbO7

The RE3+ doped YbNbO4 and Yb3NbO7 nanophosphors (RE=Ho, Er and Tm) were synthesized via a calcination-assisted hydrothermal procedure. YbNbO4 intensified almost the whole up-conversion (UC)/down-conversion (DC) emissions of RE3+ by ∼2 times when compared with Yb3NbO7 components, indicating that a lower symmetry environment in the former case is more favorable for photoluminescence. UC luminescence in each case was dominated by a green band at ∼539 nm for Ho3+ and a NIR band at ∼803 nm for Tm3+, while doping YbNbO4 and Yb3NbO7 with Er3+ separately yielded the slightly stronger green 556 nm and red 658 nm emissions. The UC/DC luminescence mechanisms were elaborated via Yb3+ → RE3+ forward/backward energy transfer and cross relaxation.

Luminescent and magnetic Y2O3: Er3+-Yb3+@γ-Fe2O3 bifunctional broadband emitting nanocomposites

The development of novel nanocomposites containing upconverting luminescent materials and magnetic nanoparticles have shown their potential applications in the hyperthermia and bio-imaging. In this regards, the search for new class of nanocomposites, which is responsive to magnetic and optical guiding in medical fields are in demand. To resolve the problem, bifunctional upconverting Y2O3: Er3+-Yb3+@γ-Fe2O3 nanocomposites have been synthesized through ball milling approach. Nanocomposites are able to upconvert NIR photons into overall yellowish-white colour broadband visible emission in 400–900 nm wavelength range at room temperature under 980 nm CW laser diode excitation. Thermal conductivity study shows an improved phonon scattering process in the Y2O3: Er3+-Yb3+@γ-Fe2O3 (∼ 0.0681 W/mK) nanocomposites as compared to Y2O3: Er3+-Yb3+ (∼ 0.0750 W/mK) phosphors due to grain boundary expansion. Broadband UC emission is originated via Yb-Yb dimer formation and heat associated continuum emission is reported due to photon avalanche (∼ 6 NIR photons) phenomenon. Besides, it also exhibits the attraction ability towards the magnet. Therefore, the developed nanocomposites can be used in converting the NIR radiation into broadband upconversion emission and luminescence imaging applications.

Strong red upconversion luminescence of NaYF4: Yb3+, Er3+ through Sc3+ ions doping for temperature sensing

Strong red upconversion luminescence of NaYF4: Yb3+, Er3+ through Sc3+ ions doping for temperature sensing

Unlocking nature’s brilliance: using Antarctic extremophile Shewanella baltica to biosynthesize lanthanide-containing nanoparticles with optical up-conversion

Both lanthanide-containing and fluorine-containing nanomaterials present challenging targets for microbial biosynthesis because these elements are toxic to most bacteria. Here, we overcome these challenges by using an Antarctic Shewanella baltica strain that tolerates these elements and report the first biosynthesis of lanthanide-doped fluoride nanoparticles (NPs) from them. NaYF4 NPs doped with Er3+/Yb3+ are prototypical lanthanide-based upconverting nanoparticles (UCNPs) with upconverted luminescence at visible wavelengths under infrared excitation. However, their synthesis employs high precursor concentrations, organic solvents, and elevated temperatures. Microbial biosynthesis offers a greener alternative but has not been explored for these materials. Here, we harness an extremophile S. baltica strain to biosynthesize UCNPs at room temperature, based upon its high tolerance for fluoride and lanthanide ions and the observation that tolerance of lanthanides increased in the presence of fluoride. Our biosynthesis produces electron-dense nanostructures composed of Na, Y, F, Yb, and Er in the bacterial periplasm, adhered to the outer cell membrane, and dispersed extracellularly, which exhibited up-converted emission under 980 nm excitation. This suggests that extracellular or periplasmic mineralization of lanthanides as fluorides protects the bacteria from lanthanide toxicity. Subsequent heating both enhanced upconverted emission from UCNPs and allowed observation of their crystallinity in transmission electron microscopy (TEM). This work establishes the first biosynthesis of NaYF4:Yb: Er UCNPs, advancing both nanotechnology and biotechnology.Graphical

Novel troponin fragmentation assay to discriminate between Takotsubo syndrome and acute myocardial infarction.

Cardiac troponin levels are elevated in Takotsubo syndrome (TTS) with significant overlap to acute myocardial infarction (MI). Long and intact cardiac troponin T (cTnT) forms are typical for MI. This study sought to assess whether the fragmentation composition of cTnT release in TTS differs from MI. The concentration of long molecular forms of cTnT (long cTnT) was measured with a novel upconversion luminescence immunoassay and total cTnT with a commercial high-sensitivity cTnT assay in 24 TTS patients and in 84 Type 1 MI patients. The ratio of long to total cTnT (troponin ratio) was determined as a measure of cTnT fragmentation. Troponin ratio was lower in TTS patients 0.13 [0.10-0.20] vs. 0.62 [0.29-0.96], p<0.001). In the ROC curve analyses, troponin ratio showed a better predictive power than total cTnT in discriminating TTS and MI patients (AUC 0.869 [CI95% 0.789-0.948)] vs. 0.766 [CI95% 0.677-0.855], p=0.047). When restricting the analysis to patients with total cTnT below 1200 ng/L (maximal value in TTS patients), the respective AUC values for total cTnT and troponin ratio were 0.599 (CI 95% 0.465-0.732) and 0.816 (CI95% 0.712-0.921), p =0.003). At a cutoff point of 0.12, troponin ratio correctly identified 95% of MI patients and 50% of TTS patients. In contrast to Type 1 MI, only a small fraction of circulating cTnT in TTS exists in intact or long molecular forms. This clear difference in troponin composition could be of diagnostic value when evaluating patients with cTnT elevations and suspicion of TTS. URL: https://www.clinicaltrials.gov; Unique identifier: NCT04465591.

Sodium Assists Controlled Synthesis of Cubic Rare-Earth Oxyfluorides Nanocrystals for Information Encryption and Near-Infrared-IIb Bioimaging.

Rare-earth oxyfluoride (REOF) colloidal nanocrystals (NCs) suffer from a low photoluminescence efficiency due to their small size with poor crystallinity and a detrimental surface quenching effect. Herein, we introduce an innovative approach that involves doping sodium ions into REOF NCs to produce monodisperse, size-controllable, well-crystallized, and highly luminescent colloidal REOF core/shell NCs. The Na+ doping allows for successfully synthesizing the cubic REOF NCs with a tunable size from 6 to 30 nm. Further fabrication of the core/shell NCs doped with Na+ results in enhancements up to 1062 (Ho3+), 1140 (Er3+), and 2212 (Tm3+) folds in upconversion luminescence and 17.7 folds (Er3+) in downconversion luminescence compared to that of core/shell NCs without doping Na+ ions. These NCs were subsequently developed into multicolor luminescent inks, demonstrating significant potential application for information security, and used for near-infrared-IIb (NIR-IIb) (1500-1700 nm) in vivo imaging, which exhibits a high-resolution in vivo dynamic imaging capability with a signal-to-noise ratio of 5.28. These results present the way to the controlled synthesis of efficient luminescent cubic LuOF: RE3+/LuOF core/shell NCs, expanding the toolkit of rare-earth doped NCs in diverse applications such as advanced encoding encryption, varied fluorescence imaging, and biomedicine.

Temperature dependent upconversion luminescence of GdScO3 phosphors with low phonon energy for optical thermometry

Temperature dependent upconversion luminescence of GdScO3 phosphors with low phonon energy for optical thermometry

Multi-Wavelength Excitable Multicolor Upconversion and Ratiometric Luminescence Thermometry of Yb3+/Er3+ Co-Doped NaYGeO4 Microcrystals.

Excitation wavelength controllable lanthanide upconversion allows for real-time manipulation of luminescent color in a composition-fixed material, which has been proven to be conducive to a variety of applications, such as optical anti-counterfeiting and information security. However, current available materials highly rely on the elaborate core-shell structure in order to ensure efficient excitation-dependent energy transfer routes. Herein, multicolor upconversion luminescence in response to both near-infrared I and near-infrared II (NIR-I and NIR-II) excitations is realized in a novel but simple NaYGeO4:Yb3+/Er3+ phosphor. The remarkably enhanced red emission ratio under 1532 nm excitation, compared with that under 980 nm excitation, could be attributed to the Yb3+-mediated cross-relaxation energy transfers. Moreover, multi-wavelength excitable temperature-dependent (295-823 K) upconversion luminescence realizes a ratiometric thermometry relying on the thermally coupled levels (TCLs) of Er3+. Detailed investigations demonstrate that changing excitation wavelength makes little difference for the performances of TCL-based ratiometric thermometry of NaYGeO4:Yb3+/Er3+. These findings gain more insights to manipulate cross-relaxations for excitation controllable upconversion in single activator doped materials and benefit the cognition of the effect of excitation wavelength on ratiometric luminescence thermometry.

Opto/Thermoresponsive Multimode Luminescence in Eu- and Er-Activated CaF2 Phosphor for High-Security Anticounterfeiting.

As the landscape of information storage and security continues to evolve, the deployment of sophisticated anticounterfeiting strategies with robust security features and multimodal luminescent capabilities becomes imperative. In this work, Eu3+ and Er3+ ions are codoped into CaF2 phosphors to achieve multimodel optical output. The self-reduction of Eu3+ within the CaF2 matrix gives rise to the coexistence of Eu3+ and Eu2+ ions, which manifests as a color transition from orange to blue as the excitation wavelength is varied from 300 to 335 nm. Moreover, the distinct temperature-dependent behaviors of Eu3+ and Eu2+ ions underscore the material's visible temperature-sensitive luminescence properties, characterized by remarkable thermal sensitivity (Sa = 0.0156 K-1, Sr = 0.83%K-1). Additionally, the strategic introduction of Er3+ ions adds an extra dimension, enabling the realization of color-tunable upconversion luminescence through the fine-tuning of Er3+ concentration. This synergistic integration culminates in the establishment of an efficient three-path authentication model within the CaF2 host matrix, facilitating a dynamic multicolor response to changes in the excitation wavelength and temperature. By harnessing these diverse luminescent modalities, the study delivers a versatile and potent anticounterfeiting solution, advancing the frontiers of information security.

Enhanced upconversion luminescence of Er3+/Y3+ co-doped tellurite glasses for volumetric three-dimensional display

Large-sized Er3+/Y3+ co-doped tellurite glasses with high image quality were prepared by a conventional melt-quenching method for volumetric three-dimensional display. The effects of the concentration of Er3+ and Y3+ on the two-frequency upconversion luminescence properties and volumetric three-dimensional display were investigated. Under dual-wavelength excitation at 850 nm and 1550 nm, the two-frequency two-step upconversion luminescence intensity at 546 nm in the Er3+/Y3+ co-doped tellurite glass was significantly enhanced by about 44% compared with that in the Er3+ doped tellurite glass. However, the upconversion luminescence mechanism and its dynamic process were further obtained. A range of the high-resolution and high-contrast volumetric three-dimensional images can be achieved in the Er3+/Y3+ co-doped tellurite glass with optimal doping concentration, utilizing a coordinated control system of galvanometer scanner and digital micro-mirror devices. The results indicate that Er3+/Y3+ co-doped tellurite glass has promising potential for widely volumetric 3D displays.