Enhancement Of Emission Intensity Research Articles

Amelioration in the Detection of Chlorine Using Electric Field Assisted LIBS

The detection of chlorine and improvement in its detection has remained a challenge despite the use of a single pulse and a dual pulse laser induced breakdown spectroscopic technique (LIBS). In this article, we presented an alternate technique for improving the detection of chlorine (Cl) using LIBS in conjunction with an external electric filed. A comparison of the emission intensity enhancement and plasma parameters in the absence and presence of an external field has been also presented. The implication of the presented technique for the detection of Cl is much easier and inexpensive as compared with the dual pulse LIBS.

A highly selective fluorescent anthracene-based chemosensor for imaging Zn2+ in living cells and zebrafish

A new fluorescent chemosensor (An3) bearing anthracenyl rings was designed and developed for detection of Zn2+. Addition of Zn2+ into An3 gave rise to a fluorescent turn-on response at 424 nm whereas Al3+, Cd2+, Co2+, Cu2+, K+, Mg2+, Zn2+, Ca2+, Fe3+, Mn2+, Ni2+, Pb2+, and Hg2+ did not induce any emission intensity enhancement. Furthermore, the probe exhibited high selectivity toward Zn2+ and a very low detection limit (36 nM) based on chelation-enhanced fluorescence. Theoretical calculations revealed the possible formation of 1:1 and 1:2 complexes between An3 and Zn2+. In bioimaging experiments, the chemosensor displayed low cytotoxicity and good biocompatibility, rendering it an effective tool for fluorescent visualization of Zn2+ in living cells and zebrafish models.

High-efficient, spherical and thermal-stable carbon dots@silica fluorescent composite as rare earth-free phosphors for white LED

This paper reported a facile synthesis path to realize high-luminescent rare-earth-free composite powder, by embedding blue/green-emitting N-doped carbon dots into silica nano-spheres (CD@SiO2). Carbon dots were evenly dispersed in CD@SiO2 composites and eventually the aggregation-induced luminescence quenching is eliminated. Compared to the naked CDs, CD@SiO2 composites exhibit perfectly spherical morphology with average size of ~200 nm, significantly enhanced emission intensity (>4 times) and better thermal stability (T50 > 150 °C). As-synthesized CD@SiO2 own strong blue/green emission with high quantum efficiency (QE) over 60%. White LEDs prototypes with promising properties, i.e. CRI = 89.1, CCT = 4850 K and CIE coordinates = (0.3514, 0.3715), were fabricated by combining blue/green CD@SiO2 and red CdTe@CaCO3 composites with NUV chip. All results indicate that these rare-earth-free, mono-dispersed spherical, and thermal-stable composite materials with efficient blue/green emission could be an exceptional choice as phosphors for LED application.

A Near-infrared Turn-on Fluorescent Sensor for Sensitive and Specific Detection of Albumin from Urine Samples.

A readily synthesizable fluorescent probe DMAT-π-CAP was evaluated for sensitive and selective detection of human serum albumin (HSA). DMAT-π-CAP showed selective turn-on fluorescence at 730 nm in the presence of HSA with more than 720-fold enhancement in emission intensity ([DMAT-π-CAP] = 10 μM), and rapid detection of HSA was accomplished in 3 s. The fluorescence intensity of DMAT-π-CAP was shown to increase in HSA concentration-dependent manner (Kd = 15.4 ± 3.3 μM), and the limit of detection of DMAT-π-CAP was determined to be 10.9 nM (0.72 mg/L). The 1:1 stoichiometry between DMAT-π-CAP and HSA was determined, and the displacement assay revealed that DMAT-π-CAP competes with hemin for the unique binding site, which rarely accommodates drugs and endogenous compounds. Based on the HSA-selective turn-on NIR fluorescence property as well as the unique binding site, DMAT-π-CAP was anticipated to serve as a fluorescence sensor for quantitative detection of the HSA level in biological samples with minimized background interference. Thus, urine samples were directly analyzed by DMAT-π-CAP to assess albumin levels, and the results were comparable to those obtained from immunoassay. The similar sensitivity and specificity to the immunoassay along with the simple, cost-effective, and fast detection of HSA warrants practical application of the NIR fluorescent albumin sensor, DMAT-π-CAP, in the analysis of albumin levels in various biological environments.

Design of a Fluorescence Turn-on and Label-free Aptasensor Using the Intrinsic Quenching Power of G-Quadruplex to AMT.

A novel fluorescent aptasensor based on the G-quadruplex induced fluorescent quenching of psoralen and the competitive interactions between 4'-aminomethyl-4,5',8-trimethylpsoralen (AMT), adenosine triphosphate (ATP) and G-rich DNA functionalized split ATP aptamer was proposed. The binding of ATP to the G-rich DNA functionalized split aptamer induced a significant enhancement in fluorescence emission intensity while undergoing excitation at 340 nm. Under the optimal conditions, the developed aptasensor showed high selectivity and good accuracy for detecting ATP. The practicality of the proposed aptasensor has been confirmed by successfully analyzing ATP in spiked human blood serum samples with satisfactory results. As far as we know, this is the first time that the intrinsic quenching ability of G-quadruplex was applied to simply construct a fluorescence turn-on and label-free aptasensor. On account of the superiority of the simplicity of the design strategy, more work is expected in the future to develop a variety of novel sensors for other important analytes using the quenching capability of G-quadruplex through reasonable designs.

A novel upconversion emission material based on Er3+ - Yb3+ - Mo6+ tridoped Hydroxyapatite/Tricalcium phosphate (HA/β-TCP)

In this paper, a novel material based on Er-Yb-Mo tri-doped HA/β-TCP phosphor for intense green up-conversion (UC) emission was successfully synthesized by solid-state reaction method. X-ray diffraction (XRD) measurements verified that the materials including a trace amount of HA phase has a hexagonal structure and main β-TCP phase has a rhombohedral structure, which is controlled by the doped ions. Under excitation wavelength of 976 nm laser diode, the HA/β-TCP:Er-Yb-Mo phosphor showed strong green UC emission band at 520/556 nm and weak red emission band at 656 nm which are attributed to (2H11/2, 4S3/2) - 4I15/2, 4F9/2 - 4I15/2 transition of the Er3+ ion, respectively. Remarkably, compared with the sample without Mo6+, the green emission intensities increased ∼650 times was achieved by using Er3+-Yb3+-Mo6+ doped phosphor. The high efficiency of the UC can be attributed to novel energy transfer process from |2F7/2, 3T2> state of Yb3+ - MoO42− dimer to the 4F7/2 of Er3+ ions. Moreover, the grain orientations due to the effect of Mo6+ ions doped in β-TCP phosphor could play an important role in the enhancement of UC emission intensity. These results indicate that the HA/β-TCP: Er-Yb-Mo phosphor has potential application in biological imaging and medicine.

Synthesis of Ba2CaZn2Si6O17:Eu2+ Phosphors: Synthesis, Microstructure and Luminescence Characteristics

In this investigation, Ba2CaZn2Si6O17:Eu2+ phosphor (BCZSOE) was successfully synthesized through the facile solid-state approach. Accordingly, spherical/commercial SiO2 particles were used through synthesizing BCZSOE phosphors. The crystal structure and microstructure of the produced phosphors were characterized using powder X-ray diffraction, field emission scanning electron microscope and high-resolution transmission electron microscope (HRTEM) instruments, while the luminescence properties of BCZSOE materials were analyzed by a photoluminescence (PL) analyzer. It was interestingly found that the use of spherical silica resulted in an uniform grain size distribution of BCZSOE phosphor in the range of 120–180 nm. In addition, the HRTEM images showed that the soaking time within the solid-state procedure was one of the most important parameters for the successful synthesis of BCZSOE compound. The luminescence emission spectra revealed that the use of silica spheres gave rise to the enhanced emission intensity than that of commercial silica particles. In addition, it was concluded that the emission bands at the wavelengths of 447 and 505 nm were due to the substitution of Ca2+ and Ba2+ by Eu2+ ions, respectively.

Y3+ substituent tuning of Sr3(PO4)2:Eu2+/Mn2+ with enhanced emission intensity, tunable luminescence, and improved thermal stability

In order to improve luminescence properties of phosphor, the cation substitution was considered one of the most effective ways. For Sr3(PO4)2:Eu2+, the luminescence properties may be improved by doped Y3+, and experimental results show the emission intensity enhanced two times and the thermal stability also increased from 93 % to 98 %. Generally, the emission intensity of Mn2+ for Sr3(PO4)2:Mn2+ and co-doped Eu2+/Mn2+ in Sr3(PO4)2 is really weak, however, when incorporated Y3+, it was enhanced. For Sr2.765-yY0.15(PO4)2:0.01Eu2+,yMn2+, emission peaks of Eu2+ and Mn2+ are observed located at 420nm and 579nm, respectively, and the value of IMn2+/IEu2+ gradually enhancement from 0 to 0.35, when Mn2+ concentration increases from 0 to 0.20. In addition, the energy transfer from Eu2+ to Mn2+ is proved, and the energy transfer mechanism is dipole-dipole interaction. Finally, series of color-tunable phosphors are achieved by properly adjusting Mn2+ concentration. The results indicate that cation substitution is very effective method for improving the luminescent properties of phosphors.

CQD@γ-Fe2O3 multifunctional nanoprobe for selective fluorescence sensing, detoxification and removal of Hg(II)

In this paper we have developed a simple integrated nanoprobe that combines fluorescent carbon quantum dots (CQD) and superparamagnetic magnetic iron oxide(SPION) equipped with –SH, -COOH functionalization for sensing and removal of mercury from aqueous medium. The probe has diminished fluorescence due to photoelectron transfer between CQD fluorophore and magnetic nanoparticle. A remarkable enhancement in fluorescence emission intensity is achieved in presence of Hg2+ which inhibits the PET mechanism. The limit of detection of this fluorescence turn on sensing is 0.376 nM which is the lowest among all reported protocol for Hg sensing. Due to presence of abundant functional groups such as –SH, -COOH in the magnetic component the probe shows excellent mercury removal efficiency of 70%. The utility of the probe has also been explored to monitor Hg in bacteria as well as in living fish sample.

Alkyl ammonium ion-induced drastic emission enhancement of Eu(D-facam)3 in 1-butanol.

Drastic enhancements in both emission intensity and circular polarization of a Eu(iii) complex were achieved in 1-butanol solution in the presence of alkylammonium ions.

Multi-shelled upconversion nanostructures with enhanced photoluminescence intensity via successive epitaxial layer-by-layer formation (SELF) strategy for high-level anticounterfeiting

Multi-shelled upconversion nanoparticles with significantly enhanced emission intensity are synthesized via successive epitaxial layer-by-layer formation (SELF) strategy and used in dual-modal anticounterfeiting and latent fingerprint detection.

Study of interpulse delay effects on orthogonal dual-pulse laser-induced breakdown spectroscopy in bulk seawater

With the application of an orthogonal DP-LIBS excitation, when compared to SP-LIBS, significant emission intensity enhancements for a wide range of elements were obtained in seawater by using proper shorter interpulse delays.

Reshaping Hybrid Perovskites Emission with Flexible Polymer Microcavities

Thanks to versatile optoelectronic properties solution processable perovskites have attracted increasing interest as active materials in photovoltaic and light emitting devices. However, the deposition of perovskite thin films necessitates wide range solvents that are incompatible with many other solution-processable media, including polymers that are usually dissolved by the perovskite solvents. In this work, we demonstrate that hybrid perovskite thin films can be coupled with all polymer planar photonic crystals with different approaches to achieve emission intensity enhancement and reshaping using different approaches. The possibility to control and modify the emission spectrum of a solution processable perovskite via a simple spun-cast polymer structure is indeed of great interest in optoelectronic applications requiring high color purity or emission directionality. Furthermore, thanks to the ease of fabrication and scalability of solution-processed photonic crystals, this approach could enable industrial scale production of low-cost, large area, lightweight and flexible polymer-perovskite lighting devices, which may be tuned without resorting to compositional engineering.

Reduction of Sm3+ and Eu3+ ions-co-doped Al2O3–SiO2 glasses and photoluminescence properties

The reduction process of Sm3+ and Eu3+ ions doped in Al2O3–SiO2 glasses and the energy transfer phenomena between Sm2+ and Eu2+ ions were investigated. When the glass was heated with H2 gas, the H2 gas molecules diffused through the glass structure, followed by the reduction of Sm3+ to Sm2+ without forming AlOH bonds, whereas the Eu3+ ions reduced and formed AlOH bonds. The activation energy for the H2 gas diffusion in Sm3+-doped glass was higher than that of Eu3+-doped glass and the reduction of Sm3+ ions was suppressed as the Eu2O3 content increased. The photoluminescent properties caused by the energy transfer between Eu2+ and Sm2+ ions were also examined. The energy of the Eu2+:4f7→ 4f65 d1 transition effectively transferred to excite the Sm2+: 4f6→ 4f55 d1 transition, resulting in strongly enhanced emission intensities of the Sm2+: 5D0→7FJ transitions.

A novel "off-on" rhodamine-based colorimetric and fluorescent chemosensor based on hydrolysis driven by aqueous medium for the detection of Fe3.

A novel "off-on" colorimetric and fluorescent chemosensor N2,N6-bis(2-(rhodamine B amido)ethyl)pyridine-2,6-dicarboxamide (RhBEP) has been designed and synthesized, which can selectively detect the presence of Fe3+ with about 75-fold enhancement in fluorescence emission intensity at 585nm over various environmentally relevant metal cations such as Hg2+, Cu2+, Cr3+, Li+, Na+, K+, Ag+, Zn2+, Mg2+, Ca2+, Ba2+, Fe2+, Cd2+, Ni2+, Mn2+, Al3+, Bi3+ and Au3+ in PBS reaction media. The remarkable color change from UV-Vis titration experiments indicates that RhBEP can be used as a colorimetric chemosensor for Fe3+. The ultrasensitive detection limit for Fe3+ in the fluorescence measurement is down to 2.0×10-8mol·L-1. The recognition mechanism of RhBEP to Fe3+ was analyzed by Job's plot and mass spectrometry analysis. In addition, the data from fluorescent cell imaging experiments confirmed that the chemosensor RhBEP has a promising application for the detection of Fe3+ in biological systems.

A sensitive pH fluorescent probe based on triethylenetetramine bearing double dansyl groups in aqueous solutions and its application in cells.

pH fluorescent probes possess many advantages, including intracellular detection, rapid response time and nondestructive testing. In this paper, a highly selective and sensitive fluorescent pH probe based on triethylenetetramine bearing double dansyl groups (1) was synthesized. This probe offers fluorescent measurement of pH value in the range of 5.81-7.21 in aqueous solution, with an 8.64-fold enhancement of fluorescent emission intensity over the unmodified probe. Probe 1 shows a fluorescent color change from a pale yellow to bright green when the pH is increased from 5.81 to 7.21. In addition, probe 1 shows good potential as a fluorescent visualizing sensor for pH values in living GS cells of epinepheluscoioides. The mechanism of the fluorescent response of probe 1 to solution pHs was further clarified by NMR, fluorescent spectra, and UV-vis absorption spectra. The results indicate that the fluorescent emission will shift with an increase in solution pHs, due to increasing deprotonation of the nitrogen atom on the sulfonamides. Deprotonation of the sulfonamide group will inhibits the intramolecular charge transfer process between the imino group and the naphthalene ring, resulting in the recognition phenomenon of blue shift and enhancement of fluorescent emission intensity.

Enhancement of emission intensity in Ce3+‐activated aluminoborosilicate scintillating glass synthesized in air

AbstractA highly effective method of synthesizing transparent and colorless Ce3+‐activated aluminoborosilicate glass in air by high temperature melt‐quenching is reported. This is achieved by partial substitution of AlN for Al2O3 without using any reduction in atmosphere. The optimized Ce3+‐activated aluminoborosilicate scintillating glass is featured with a density of ~4.5 g/cm3 and a lifetime of 41.74 ns. Compared to the glass synthesized without AlN substitution, both the photo and raidoluminescence intensity of the optimized Ce3+‐activated aluminoborosilicate scintillating glass are enhanced by a factor of 24.4 and 6.76, respectively. The corresponding integrated raidoluminescence intensity is about 17.6% of that of BGO crystal under X‐ray excitation at 30 kV and 3 mA, respectively.

Optical analysis and separation of trivalent lanthanides in deep eutectic solvents

Deep eutectic solvents (DESs) were used for luminescence measurements in quantitative analysis of trivalent lanthanide ions and as solvents for light rare earth elements (LREE) in solid-liquid separation. The spectroscopic characteristics of lanthanide chlorides LnCl3 (Ln = Eu, Tb), respectively their aquo complexes, are described in a comprehensive study that demonstrates the significant enhancement of the phosphorescence emission intensity in DESs as polar and weakly coordinating solvent. Several DESs stabilize the lanthanide ion luminescence against changes in temperature and moisture, which is advantageous compared with the use of ionic liquids. Small amounts of water lead in certain eutectic systems even to a further increase in phosphorescence emission intensity. By investigating the solubility of lanthanide sesquioxides Ln2O3 (Ln = La, Nd, Sm, Eu, Gd, Tb, Dy) in DESs, selectivities are identified that may be of use for the separation of LREE.

Broadband light emission induced by laser absorption and optimized by thermal injection in Nd3+:Y2SiO5 ceramic powder

AbstractLaser‐induced broadband (white) light emission has been studied in different particle systems for use in light‐emitting devices. The photoinduced phenomenon occurs above a certain excitation power threshold and it is generally studied under vacuum conditions. In this work, the phenomenon is studied in neodymium‐doped yttrium silicate ceramic powder synthesized by combustion method. White light is observed when the sample is excited in ambient air with a continuous‐wave near‐infrared (λ = 808 nm) laser powered above 1.3 W. When the temperature of the sample is externally raised above 200°C, white light is observed above 1.0 W and a large enhancement of the broadband emission intensity is observed.

A novel view of the separate and simultaneous binding effects of docetaxel and anastrozole with calf thymus DNA: Experimental and in silico approaches.

DNA stands as the primary purpose of many anticancer drugs and according to the performed research on this field, some certain changes contain crucial functionalities in the regulated transcription of DNA. Therefore, the interaction between anticancer drugs and DNA play an important role in understanding their function and also provide a better groundwork for producing more efficient and newer drugs. Here, the interaction between Docetaxel (DO) and calf thymus DNA (ct DNA), in the presence and absence of Anastrozole (AN), has been examined through the usage of different methods that include isothermal titration calorimetry, multi-spectroscopic, viscometry, and molecular docking techniques. Interaction studies have been performed by preparing different molar ratios of DO with the constant ct DNA and AN concentration at pH = 6.8. The binding constants have been calculated to be 7.93 × 104 M-1 and 6.27 × 104 M-1, which indicate the strong binding of DO with ct DNA double helix in the absence and presence of AN, respectively. Thermodynamic parameters, which were obtained from fluorescence spectroscopy and isothermal titration calorimetry, have suggested that the binding of DO and AN to ct DNA as binary and ternary systems have been mainly driven by the electrostatic interactions. The relative viscosity of ct DNA has increased upon the addition of DO and AN, which confirms the interaction mode. A competitive binding study has reported that the enhanced emission intensity of ethidium bromide (EB) and acridine orange (AO), in the presence of ct DNA, have been quenched through the addition of DO and Anastrozole as binary and ternary systems. As it is indicated by these findings, DO is capable of displacing EB and AO from their binding site in ct DNA; hence, it can be concluded that DO and AN are able to intercalate into the base pairs of ct DNA in binary and ternary systems. Molecular docking studies have corroborated the mentioned experimental results.