Blue Light Excitation Research Articles

Fluorescent Detection of Vestibular Schwannoma Using Intravenous Sodium Fluorescein In Vivo.

Vestibular schwannoma (VS) are intracranial tumors caused by merlin deficiency. Sodium fluorescein (SF) is a fluorescent compound that accumulates in various intracranial tumors, causing tumors to emit green fluorescence after blue light excitation. Intravenous SF preferentially deposits in VS, helping surgeons differentiate tumor from surrounding tissue. Merlin-deficient Schwann cells were grafted onto cochleovestibular nerves of immunodeficient rats. Rats were randomized to receive SF (7.5 mg/kg; n = 5) or saline (n = 3). Tissues were harvested at 1 hour and photographed in white and blue light. Sixteen surgeons identified and marked the tumor-tissue interfaces on images. Fluorescence was measured on tissue specimens using the IVIS imaging system and on tissue cross-sections obtained with confocal microscopy. Western blot was performed to measure levels of organic anion transporting polypeptide (OATP), a drug transporter specific for SF. Under blue light, tumors from SF rats demonstrated bright green fluorescence under direct visualization, higher fluorescence measurements on tissue specimens (p < 0.001), and more SF deposition on tissue cross-sections (p < 0.001), when compared with surrounding tissues and placebo rats. Surgeons were better able to distinguish the tumor-tissue interfaces in SF rats. Furthermore, the expression level of OATP1C1 was significantly higher in tumors than in surrounding tissues (p < 0.0001). In a xenograft model of VS, intravenous SF preferentially deposits in tumors, compared with normal surrounding tissue. Under blue light, tumors emit an intense green fluorescence that can help surgeons differentiate tumor from critical structures nearby, which may improve clinical outcomes in complicated VS surgery.

Luminescence characteristics of newly-developed MgB4O7:Ce3+,Na+ phosphor as an OSL dosimeter

In this study, dosimetric properties of Ce3+ and Na+ doped magnesium tetraborate (MgB4O7) phosphors synthesized by the solution combustion synthesis (SCS) method were investigated using optically stimulated luminescence (OSL) technique to develop OSL radiation dosimetry. The concentrations of Ce3+0.3%wt and Na+1–14%wt dopants in MgB4O7 were incorporated into it to improve the efficiency of luminescence. The results showed that the effect of Na+ substitution on MgB4O7:Ce3+0.3%wt lattice induced a remarkable improvement of both its thermoluminescence (TL) and OSL signals. The highest OSL signal of the synthesized phosphor was recorded at the MgB4O7:Ce3+0.3%wt,Na+14%wt phosphor. Its TL glow curve consists of two peaks located at ~70 °C and ~230 °C with a heating rate of 2 °C/s. These TL peaks were found to be optically sensitive to blue light excitation (λ = ~470 nm). X-ray diffraction (XRD), scanning electron microscopy (SEM), radioluminescence (RL) techniques have been employed to characterize the synthesized phosphor. The XRD pattern of MgB4O7:Ce3+0.3%wt,Na+14%wt phosphor with orthorhombic phase was observed in the specimen sintered at 900 °C. The RL spectrum of the MgB4O7:Ce3+0.3%wt,Na+14%wt phosphor revealed a strong and a weak emission peak located UV and red regions, respectively. OSL dosimetric properties of the phosphor were studied under beta radiation of 90Sr/90Y. The phosphor exhibited good linearity between 1 and 100 Gy. Minimum detectable dose (MDD) of the phosphor was calculated as 0.73 mGy. A good reusability property was determined up to 20 experimental cycles with a deviation of 4.5%. Short-time fading up to 24 h and long-time fading up to 4 weeks were studied. The results shows the MgB4O7:Ce3+0.3%wt,Na+14%wt phosphor can be proposed as a potential OSL dosimetry for radiation dose measurements in medicine using OSL technique.

Effects of Emulsifier Type and Post-Treatment on Stability, Curcumin Protection, and Sterilization Ability of Nanoemulsions.

Curcumin has a high inhibitory effect on many potential diseases caused by bacteria and fungi. However, its degradability and low water solubility limit its application. Loading curcumin with an emulsion delivery system can overcome these problems. Five different types of emulsifiers were used to prepare the curcumin-loaded nanoemulsions, namely, Tween 80 (T80), Span 80 (S80), sodium dodecyl sulfate (SDS), soybean protein isolate (SPI), and lecithin (LEC). The effects of emulsifier types and post-treatment methods on emulsion stability and curcumin-load efficiency were studied. In addition, photodynamic inactivation was used to test the antibacterial effect of nanoemulsions on Escherichia coli under blue light excitation. The five types of emulsifiers could form uniform emulsions with good storage stability and with antibacterial capacity on Escherichia coli. Among them, the T80 and LEC emulsions had good stability, coating effect, and sterilization performance under heating or room temperature. Both curcumin-loaded bactericidal emulsions had the potential for large-scale applications. A nanoemulsions delivery system could effectively improve the dispersion and chemical stability of curcumin in water. An emulsion loaded with antibacterial photosensitizer represents a new idea for the storage and preservation of food commodities.

Tb3+-doped fluorescent glass for biology.

Optical investigation and manipulation constitute the core of biological experiments. Here, we introduce a new borosilicate glass material that contains the rare-earth ion terbium(III) (Tb3+), which emits green fluorescence upon blue light excitation, similar to green fluorescent protein (GFP), and thus is widely compatible with conventional biological research environments. Micropipettes made of Tb3+-doped glass allowed us to target GFP-labeled cells for single-cell electroporation, single-cell transcriptome analysis (Patch-seq), and patch-clamp recording under real-time fluorescence microscopic control. The glass also exhibited potent third harmonic generation upon infrared laser excitation and was usable for online optical targeting of fluorescently labeled neurons in the in vivo neocortex. Thus, Tb3+-doped glass simplifies many procedures in biological experiments.

Broadband near-infrared BaMSi3O9:Cr3+ (M = Zr, Sn, Hf) phosphors for light-emitting diode applications

Cr3+-Doped BaMSi3O9 (M = Zr, Sn, Hf) NIR-emitting phosphors have been developed, which exhibit a broad NIR emission band over 650–1200 nm with a tunable band maximum longer than 800 nm and a FWHM of more than 155 nm upon blue light excitation.

Structure and luminescence behaviour of a novel red-emitting fluoroperovskite for display backlight application.

In this work, we present a brand-new narrowband red-emitting fluoroperovskite via the introduction of Mn4+ into NaZnF3 through a facile co-precipitation method at room temperature. The physicochemical properties of the fluoroperovskite such as crystal and electronic structures, morphology, and elemental composition, as well as its spectroscopic properties such as luminescence behaviours and optical performance were characterized and investigated in detail. Evidence shows that NaZnF3:Mn4+ exhibits a uniform particulate shape with single-phase crystallinity. By virtue of the non-equivalent substitution and the [MnF6] octahedral distortion in the fluoride host, sharp red emissions of phonon sidebands and the zero-phonon line upon blue light excitation are identified. Benefiting from the unique spectral feature, a wide colour gamut of 104.1% NTSC is achieved by coating β-SiAlON:Eu2+ and NaZnF3:Mn4+ on an InGaN chip, indicating the potential use of the Mn4+ fluoroperovskite as a colour converter for display backlight application.

Crystal structure, photoluminescence and afterglow properties of red-emitting phosphors Ca4Nb2O9:Pr3+ for AC-LEDs

A novel Ca4Nb2O9:Pr3+ short-afterglow phosphor exhibits efficient red emission under blue light excitation, which can be used to compensate the time gap of AC-LEDs.

Cr3+‐Doped Sc‐Based Fluoride Enabling Highly Efficient Near Infrared Luminescence: A Case Study of K2NaScF6:Cr3+

AbstractThe development of highly efficient and thermally stable broadband near‐infrared (NIR) luminescence materials is a great challenge to advance the next‐generation smart NIR light source. Benefitting from the low phonon energy and relatively weak electron phonon coupling effect of the fluoride, K2NaScF6:Cr3+ phosphor is designed and obtained, which demonstrates a full width at half maximum of 100 nm peaking at ≈765 nm. Upon blue light excitation, the phosphor exhibits a high quantum efficiency of 74% and its emission intensity at 150 °C can keep 89.6% of the initial value at 25 °C. An NIR output power of 159.72 mW (input electric power, 1094 mW) with a high photoelectric conversion efficiency of ≈14.60%, light‐emitting diode (LED) device is presented based on this K2NaScF6:Cr3+ phosphor. Furthermore, applying the high‐power NIR phosphor‐converted LED device as lighting source, clear and quick veins imaging and recognition in fingers, palm, wrist, and arm of the human hand are first realized, suggesting K2NaScF6:Cr3+ phosphor has high promise in practical applications.

A facile two-step synthesis of an efficient narrow-band red-emitting K2NbF7:Mn4+ phosphor for warm white LEDs and its thermal quenching behavior

Mn4+-doped fluoride phosphors exhibit narrow red line emission under blue light excitation. Such phosphors can improve the color rendering index (CRI) and reduce the color temperature of white LEDs. In this study, a series of K2NbF7:Mn4+ red phosphors were successfully synthesized by a facile two-step synthesis. The structure, composition, morphology and spectral properties were studied by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM) and photoluminescence spectroscopy. The obtained K2NbF7:Mn4+ can emit multiple sharp emission peaks in the range of 600–650 nm under excitation of ~371 nm or ~471 nm. In particular, this phosphor has a strong zero phonon line (ZPL) emission at 620 nm and an internal quantum efficiency (IQE) ~82%. The effects of Mn4+ doping amount, hydrothermal reaction temperature and HF concentration on spectral properties were discussed and the optimal synthesis conditions were obtained. The thermal quenching behavior of K2NbF7:Mn4+ red phosphor was studied and the activated energy was determined to be 0.66 eV. The fabricated white light-emitting diode (w-LED) with a low correlated color temperature (CCT) at 3426 K and a high luminous efficiency of 134.4 lm/W was obtained by using the K2NbF7:Mn4+, which indicates that K2NbF7:Mn4+ could be a potential red component for warm w-LEDs.

Jelly-Inspired Injectable Guided Tissue Regeneration Strategy with Shape Auto-Matched and Dual-Light-Defined Antibacterial/Osteogenic Pattern Switch Properties.

Periodontitis is a bacterial infectious disease leading to the loss of periodontal supporting tissues and teeth. The current guided tissue regeneration (GTR) membranes for periodontitis treatments cannot effectively promote tissue regeneration for the limited antibacterial properties and the excessively fast degradation rate. Besides, they need extra tailoring according to variform defects before implantation, leading to imprecise match. This study proposed an injectable sodium alginate hydrogel composite (CTP-SA) doped with cubic cuprous oxide (Cu2O) and polydopamine-coated titanium dioxide (TiO2@PDA) nanoparticles for GTR. Inspired by the gelation process of the jelly, the phase change (liquid to solid) of CTP-SA after injection could automatch variform bone defects. Meanwhile, CTP-SA exhibited broad-spectrum antibacterial capabilities under blue light (BL) irradiation, including Streptococcus mutans (one of the most abundant bacteria in oral biofilms). Moreover, the reactive oxygen species released under BL excitation could accelerate the oxidation of Cu+ to Cu2+. Afterward, osteogenesis could be enhanced through two factors simultaneously: the stimulation of newly formed Cu2+ and the photothermal effect of CTP-SA under near-infrared (NIR) irradiation. Collectively, through this dual-light (blue and NIR) noninvasive regulation, CTP-SA could switch antibacterial and osteogenic modes to address requirements of patients at different healing stages, thereby realizing the customized GTR procedures.

Facile synthesis of yellow luminescence from zinc coordination compound based on hydroxyquinoline under the blue-light excitation

In this paper, a novel Zn(L1)2(L2) phosphor with yellow light under blue-light excitation was synthesized using simple one pot method by introducing the second ligand 4-dimethylaminopyridine (L2) to the reaction that uses 5-chloro-8-hydroxyquinoline (L1) and zinc acetate to prepare the coordination compound Zn(L1)2. The structure of Zn(L1)2(L2) was determined with single crystal X-ray diffraction techniques. Besides, the compounds Zn(L1)2 and Zn(L1)2(L2) were characterized by Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), fluorescence spectroscopy, and thermo-gravimetric analysis (TGA). Compared with the compound Zn(L1)2, the optimal excitation and emission wavelengths of the compound Zn(L1)2(L2) have red-shifted, with the excitation wavelength of 467 nm and the emission wavelength of 574 nm. The special luminescent properties and simple synthesis method of the Zn(L1)2(L2) make it become a promising candidate in the field of white-light-emitting diodes.

Novel red phosphor for LED applications

Abstract The un-doped and Eu3+ doped BaY2O4 phosphors were synthesized by the standard solid state reaction method, heated at 1200 °C temperature. The dopant ion concentration was taken as 0.1, 0.5, 1.0, 1.5 and 2.0 mol% to know the effect of dopant ion in the host material. The structure, morphology of the phosphors was characterized by X-ray diffraction, scanning electron microscopy. The results show that the distribution of the pure phase BaY2O4: Eu3+ particles after annealing at 1200 °C, and the shape was irregular with size of particle 0.2 μm to 0.4 μm. Luminescence properties of BaY2O4: Eu3+ phosphors are investigated by the excitation and emission spectroscopy at room temperature region. The excitation spectra monitored at 613 nm is composed of a broad band (200 – 300 nm) and a series of sharp peaks, at 395 nm and 467 nm, which are matching with the output wavelengths of nUV LED and blue LED chips. The main emission spectra under blue light excitation is 5D0→7F2 electric dipole transition of Eu3+ ion with a strong red light, so that the BaY2O4: Eu3+ phosphor may be a better candidate as red component for the generation of white LED.

Redox-Neutral Photocatalytic C−H Carboxylation of Arenes and Styrenes with CO2

Summary Carbon dioxide (CO2) is an attractive one-carbon (C1) building block in terms of sustainability and abundance. However, its low reactivity limits applications in organic synthesis as typically high-energy reagents are required to drive transformations. Here, we present a redox-neutral C─H carboxylation of arenes and styrenes using a photocatalytic approach. Upon blue-light excitation, the anthrolate anion photocatalyst is able to reduce many aromatic compounds to their corresponding radical anions, which react with CO2 to afford carboxylic acids. High-throughput screening and computational analysis suggest that a correct balance between electron affinity and nucleophilicity of substrates is essential. This novel methodology enables the carboxylation of numerous aromatic compounds, including many that are not tolerated in classical carboxylation chemistry. Over 50 examples of C─H functionalizations using CO2 or ketones illustrate a broad applicability. The method opens new opportunities for the valorization of common arenes and may find application in late-stage C─H carboxylation.

Synthesis, surface and photoluminescence properties of Sm3+ doped α-Bi2O3

Sm3+-doped Bi2O3 (0.5–10 mol% Sm) powders were isolated by means of a co-precipitation method. The crystal structure, morphology, elemental compositions and distribution, diffuse reflectance, surface analysis and luminescence properties of the newly prepared compounds were characterized and analysed in detail. The crystal structures for the undoped and Sm3+-doped samples were monoclinic, with crystallite sizes ranging between 63 and 83 nm. Field emission scanning electron microscope analysis indicated needle-like particles, while at the higher dopant concentration the products also contained the presence of small nanorod occlusions on the needle surface. The Sm3+ substituted the Bi at certain sites in the crystal with the subsequent formation of oxygen vacancies. The band gap of the isolated products with the different Sm3+ concentration (0.5–10 mol%) remained the same at approximately 2.85 eV. Photoluminescence (PL) results revealed that blue light (490 nm) excitation produced phosphors with the strongest emission intensity at 658 nm, which is attributed to the 4G5/2 → 6H9/2, transition in the Sm3+ ion. The maximum PL was obtained for the 4 mol% Sm3+ doping concentration, after which the PL intensity decreased due to concentration quenching, which was the result of Sm3+ ion dipole-dipole interactions.

Photoreactivity of Bis-retinoid A2E Complexed with a Model Protein in Selected Model Systems

The bis-retinoid N-retinyl-N-retinylidene ethanolamine (A2E) is formed as a byproduct of visual cycle in retinal pigment epithelium (RPE). It contributes to golden-yellow fluorescence of the age pigment lipofuscin, which accumulates in RPE. Lipofuscin can generate a variety of reactive oxygen species (ROS) upon blue-light excitation. Although in model systems photoreactivity of A2E has been determined to be low, this bis-retinoid exhibited significant phototoxicity in RPE cells in vitro. Although the mechanism of A2E-mediated phototoxicity remains mostly unknown, we hypothesize that formation of A2E-adducts with different biomolecules may play an important role. In this study, we investigated the photochemical reactivity of A2E and its complex with bovine serum albumin (BSA) using UV–Vis absorption and emission spectroscopy, EPR-spin trapping, EPR-oximetry, time-resolved singlet oxygen phosphorescence, and the fluorogenic CBA probe. Our data show that A2E after complexation with this model protein photogenerated an increased level of ROS, particularly singlet oxygen. We also demonstrated the ability of A2E to oxidize BSA upon excitation with blue light in aqueous model systems. The data suggest that pyridinium bis-retinoid could oxidatively modify cellular proteins under physiological conditions.

Emission shift by co-doping and color reproducibility improvement by mixing phosphors

To achieve rich color reproducibility by blue diode excitation, we analyzed peak shift by co-doping. It is confirmed that a peak originating from a 4f-5d transition shifted by approximately 30 nm. We performed a simulation to determine the color rendering index achievable by additionally mixing red phosphor and obtained a rich value of approximately 80. The red phosphor is due to NaYF4 crystal and emitted weak emissions even for blue light excitation.

Four-Dimensional Printed Liquid Crystalline Elastomer Actuators with Fast Photoinduced Mechanical Response toward Light-Driven Robotic Functions.

Remote light exposure of photoresponsive liquid crystalline polymers has drawn great attention over the last years as an attractive strategy to generate mechanical work with high spatial resolution. To tailor these materials into practical engineering devices, it is of key importance to gain control over their morphology and thus precisely program their mechanical response, which must also be fast and relevant in magnitude. In this communication, we report the four-dimensional (4D) printing of azobenzene-containing liquid crystalline elastomers (LCEs) that respond to light. During extrusion of the LCE precursor, mesogen orientation is defined by the needle's moving direction enabling a precise definition of the director, which is later fixed by photopolymerization. Fast mechanical responses have been observed in these 4D printed LCE elements when excited with ultraviolet (UV) light. These 4D printed elements lift objects many times heavier than their own weight, demonstrating a capacity to produce effective work. Photochemical and photothermal contributions to the deformation and force have been identified. Advantageously, the use of blue and UV light excitation enables adjustment of generated forces that can be maintained even in the dark and can be released by light excitation or temperature. The demonstrated ability to generate light-responsive elements quickly delivering sufficient work paves the way for implementing remotely addressed mechanical functions to future soft robotics and engineering.

Praseodymium ion activated yellow emitting Tribarium Dibismuth Tetrakis Phosphate phosphors for solid state lighting applications

In this work, a series of Pr3+ ions are activated with different concentration (x = 0.02 ≤ 0.12) in Ba3Bi2(PO4)4 phosphors for the application of White-LEDs and their structural, surface image of sample and luminescence properties were studied. Exciting the Ba3Bi2-x(PO4)4:xPr3+ (x = 0.02 ≤ 0.12) (here after abbreviated as BaBiPO:Pr3+) phosphors with 445nm blue light, the observed emission bands are at 522, 544, 599, 645, 693 and 724 nm which correspond to the transitions 3P1 → 3H5, 3P0 → 3H5, 1D2 → 3H4, 3P0 → 3F2, 1D1 → 3H5 and 3P0 → 3F4 of praseodymium ions respectively. Among these Pr3+ concentrations, x = 0.04 yielded the maximum PL intensity. The luminescence decay time and the thermal stability of BaBiPO:Pr3+ phosphors were studied. Additionally, the present emission colour of these phosphors was found to be located in the yellowish region using CIE 1931. Finally, it is concluded that this Pr3+ activated host materials can be used as a yellowish emitting phosphors for the blue light excitation.

HF‐free molten salt route for synthesis of highly efficient and water‐resistant K2SiF6:Mn4+ for warm white LED

AbstractIt has been one of the hot issues to prepare the red‐emitting Mn4+‐doped fluoride phosphors with highly efficient and waterproofness for warm white‐light‐emitting diodes (WLEDs) by the green and environmentally friendly method. Herein, we design a novel green molten salt route to synthesize K2SiF6:Mn4+ red powder using molten NH4HF2 salt instead of HF liquor as the reaction medium. The results show that KMnO4 and MnF2 could produce Mn4+ in NH4HF2 molten salt through a reduction reaction, and the resulting Mn4+‐doped K2SiF6 exhibited a bright red emission peaked at 632 nm under blue light excitation. The luminescence intensity of the as‐obtained product after immersing into water for 24 hours maintain nearly 100% of that before soaking and emission peak shape remains unchanged. The thermal stability of the sample was evaluated by temperature‐dependent luminescence spectral intensity during heating and cooling. Furthermore, a warm white‐light‐emitting diodes (WLEDs) with an excellent color rendering index (Ra = 87.1), lower correlated color temperature (CCT = 3536K), and high luminous efficacy (116.99 lm·W−1) was fabricated based on blue chip and K2SiF6:Mn4+ and commercial yellow phosphor (Y3Al5O12:Ce3+).

Synthesis, Crystal Structure, and Visible Light Sensitized Red Luminescence of a Novel Salen-Bridged Pentanuclear Eu-Na Complex

The europium complex 1 ([Eu2Na3(bsalen)2(L)2(CH3O)(NO3)2] ⋅ 3H2O) with unusual trigonal bipyramid-shaped core [Na3Eu2] has been formed via the reaction of Eu(NO3)3 with N,N'-bis(3-methoxy-salicylidene)-ethylenediamine (bsalen2– ligand), 2-hydroxy-4-methoxybenzophenone (HL) and NaOH in the ratio of 1 : 1 : 1 : 3.5 in methanol. Crystal structure reveals that each Eu(III) ion is encapsulated in the inner cavity of bsalen2– ligand. Photoluminescence (PL) measurement results show that the europium complex exhibits intense red emission (611 nm) under blue light excitation (417 nm) with quantum efficiency of 16.9% and lifetime of 1.02 ms.