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  • First‐derivative synchronous spectrofluorimetric method for estimation of losartan potassium and atorvastatin in their pure forms and in tablets
    Luminescence (IF 1.691) Pub Date : 2020-01-19
    Norhane Attaa Bakr; Samar Saad; Yasser Elshabrawy; Manal Eid

    Losartan potassium (LOS) and atorvastatin (ATR) are used in combination for long‐term treatment of stroke and for treatment of hypertension with high‐level cholesterol. Both drugs were simultaneously determined and validated using a novel, easy, fast, and economical first‐derivative synchronous fluorescence spectroscopic method. Methanol was used as the solvent for both drugs at a Δλ 80 nm and with a scanning rate of 600 nm/min. Peaks were determined as at 288.1 nm and 263.6 nm for LOS and ATR, respectively. The proposed method was validated according to International Conference on Harmonization guidelines and, subsequently, the developed method was applicable to the analysis of the two compounds in their different formulations without interference from each other. Amplitude–concentration plots were rectilinear over the concentration ranges 1.0–10.0 μg/ml and 0.5–5.0 μg/ml for LOS and ATR, respectively. Detection limits were found to be 0.096 μg/ml and 0.030 μg/ml and quantitation limits were 0.291 μg/ml and 0.093 μg/ml for LOS and ATR, respectively. The proposed method was successfully applied to the analysis of both compounds in synthetic mixtures and in laboratory‐prepared tablets. These results were in accordance with the results acquired using the comparison method, high‐performance liquid chromatography.

    更新日期:2020-01-21
  • Luminescence properties of the Ln–EDTA complexes covalently linked to the chitosan biopolymers containing β‐diketonate as antenna ligands
    Luminescence (IF 1.691) Pub Date : 2020-01-16
    Israel F. Costa; Gilvan P. Pires; José Geraldo P. Espínola; Hermi F. Brito; Maria Claudia F.C. Felinto; Wagner M. Faustino; Ercules E.S. Teotonio

    This paper reports on the preparation, characterization, and photoluminescence properties of novel hybrid materials, in which the EDTA–Ln–L complexes (where L: H2O, acac, bzac, dbm, and tta ligands, and Ln: Eu, Gd, and Tb) were covalently linked to the precursor medium molecular weight chitosan surface (CS) matrices or on the chitosan surfaces previously crosslinked with epichlorohydrin (CSech). The emission spectra of these materials were characterized by intraconfigurational‐4fN transitions centred on the Eu3+ and Tb3+ ions. Some broad bands from the polymeric matrix were also observed in the emission spectra, however the relative intensities of the intraconfigurational bands increased significantly for systems containing diketonate ligands when the antenna effect became more efficient. The values of the radiative rates (Arad) were higher for crosslinked hybrid systems with epichlorohydrin, while nonradiative rates (Anrad) presented the opposite behaviour. These data contributed to an increase in the values of emission quantum efficiency (η) for crosslinked materials. The effect of the modification process and antenna ligand on the values of intensities, intensity parameters Ω2 e Ω4 of the Eu3+ complexes were also investigated. The results showed that the crosslinked biopolymer surfaces have great potential for applications in molecular devices light converters.

    更新日期:2020-01-17
  • A colorimetric probe for detection of Cu2+ by the naked eye and application in test paper
    Luminescence (IF 1.691) Pub Date : 2020-01-15
    Xiaorui Cao; Qi Gao; Xiaotao He; Yinjuan Bai; Wei Sun

    A novel colorimetric probe RP1 was synthesized using rhodamine derivatives and heterocyclic compounds for the purpose of detecting Cu2+. RP1 showed good selectivity, high sensitivity and affinity toward Cu2+ over other competing ions in CH3OH–H2O (1/1, v/v) solution. Absorbance intensity showed a good linear fit between probe R1 and Cu2+ over the concentration range 1–8 μM and the association constant was also calculated to be 1.145 × 105 M−1. The sensing mechanism was deduced using Job's plot, Fourier transform infrared spectroscopy, and density functional theory studies. In addition, the colorimetric experiment indicated that probe RP1 could be made into test paper to detect Cu2+ with a colour change from colourless to pink.

    更新日期:2020-01-17
  • Role of Li+ ions on the surface morphology and thermoluminescence properties of Y2O3:Tm3+ nanophosphor
    Luminescence (IF 1.691) Pub Date : 2020-01-15
    N.J. Shivaramu; E. Coetsee; H.C. Swart

    Y2O3:Tm3+ and Li+ co‐doped Y2O3:Tm3+ nanopowders were synthesized using the solution combustion method for possible application in ultraviolet (UV) light dosimetry. X‐ray diffraction revealed the crystallite sizes to be in the range 21–44 nm and 30–121 nm using the Scherrer equation and the W‐H plot relationship, respectively. Field emission scanning electron microscopy confirmed that, after co‐doping with 4 mol% concentration of Li+, the particles were spherical in nature with an average size of ~30 nm. Fourier transformed infrared spectroscopy results showed bands at wavenumbers of 556, 1499, 1704, 2342, 2358, 2973, 3433, and 3610 cm−1 that corresponded to the stretching and bending vibrations of Y–O, C=O and O–H. Thermoluminescence (TL) glow peaks for Y2O3:Tm3+ nanophosphors observed at 399 and 590 K were attributed to oxygen defects caused using UV irradiation. These oxygen defects firstly resulted in an increased prominent peak TL intensity for up to 270 min of irradiation and then a decrease. This was attributed to the presence of oxygen defect clusters that caused a reduction in recombination centres. The Li+ co‐doped sample showed peaks at 356, 430, and 583 K and its intensity sublinearly increased up to 90 min and then thereafter decreased. The TL trapping parameters were calculated using computerized glow curve deconvolution methods. The Li+ co‐doped sample exhibited less fading and high trap density under the UV radiation.

    更新日期:2020-01-17
  • Interaction of carbon nanotubes with curcumin: Effect of temperature and pH on simultaneous static and dynamic fluorescence quenching of curcumin using carbon nanotubes
    Luminescence (IF 1.691) Pub Date : 2020-01-14
    Lucia Youssef; Digambara Patra

    Curcumin (Cur) has medicinal properties, undergoes hydrolysis, and has low water solubility that limits its bioavailability and industrial usage. Different host molecules such as carbon nanotubes (CNT) can be useful in improving solubility and stabilizing Cur, therefore understanding the interaction of Cur with host molecules such as CNT is crucial. In this study, UV–visible light absorption and fluorescence spectroscopic techniques have been applied to reveal the interaction of Cur with CNT. Visible light absorption of Cur increases with CNT concentration, whereas fluorescence intensity of Cur is quenched in the presence of CNT. The obtained results confirm that fluorescence reduction is due to both static and dynamic quenching and is a result of the ground state and excited‐state complex formation. The pH environment influences the quenching rate due to deprotonation of Cur at higher pH; excess OH‐ ion concentration in the solution further discourages electrostatic interaction between the deprotonated form of Cur with CNT. It is found that at lower temperatures (<35°C) dynamic quenching is much more dominant and at higher temperatures (45°C) static quenching is more dominant. The interaction is further supported using X‐ray diffraction patterns and Fourier transform infrared spectra in the solid state, and suggests encapsulation of curcumin within the CNT. It is further evident that fluorescence quenching of Cur using CNT is further enhanced in the presence of several salts, as increase in ionic strength of the solution pushes the hydrophobic Cur molecule towards the CNT core by increasing the proximity between them.

    更新日期:2020-01-15
  • Investigation of thermoluminescence glow curves in quartz extracted from the Central Eastern Desert, Egypt
    Luminescence (IF 1.691) Pub Date : 2020-01-13
    Shrouk Farouk; Huda El‐Azab; Ahmed Gad; Hassan El‐Nashar; Nabil El‐Faramawy

    The current study investigated the thermoluminescence (TL) properties of milky quartz samples collected from the Central Eastern Desert, Egypt. The crystallinity and the elemental concentrations of the milky quartz samples were examined using X‐ray diffraction and an atomic absorption spectrometer. Samples were irradiated using a gamma source at different doses from 250 mGy up to 2 kGy. For annealing, the samples were heated at 400°C for 1 h, followed by slow cooling. Kinetic analyses for the TL glow curves were performed using new designed TL deconvolution software. The glow curves were composed of six overlapped trapping sites at 428, 468, 498, 545, 586, and 639 K. The samples also displayed a linear dose–response from 0.25 Gy up to 20 Gy and a supralinear response from 20 Gy up to 200 Gy. The samples exhibited very low sensitivity for gamma radiation compared with LiF and the minimum detectable dose was 545 μGy. From its linear nature, it was observed that the sensitivity had changed. This study recommends starting measurements of these milky quartz samples after 4 days to give established measurements.

    更新日期:2020-01-14
  • DNA bioassays based on the fluorescence ‘turn off’ of silver nanocluster beacon
    Luminescence (IF 1.691) Pub Date : 2020-01-11
    Qiu‐Lin Wen; Jun Peng; An‐Yong Liu; Jun Wang; Yi‐Lin Hu; Jian Ling; Qiu‐E Cao

    Recognition and quantification of oligonucleotide sequences play important roles in medical diagnosis. In this study, a new fluorescent oligonucleotide‐stabilized silver nanocluster beacon (NCB) probe was designed for sensitive detection of oligonucleotide sequence targets. This probe contained two tailored DNA strands. One strand was a signal probe strand containing a cytosine‐rich strand template for fluorescent silver nanocluster (Ag NC) synthesis and a detection sections at each end. The other strand was a fluorescence enhancing strand containing a guanine‐rich section for signal enhancement at one end and a linker section complementary to one end of the signal probe strand. After synthesis of the Ag NCs and hybridization of the two strands, the fluorescence intensity of the as‐prepared silver NCB was enhanced 200‐fold compared with the Ag NCs. Two NCBs were designed to detect two disease‐related oligonucleotide sequences, and results indicated that the two target oligonucleotide sequences in the range 50.0–600.0 and 50.0–200.0 nM could be linearly detected with detection limits of 20 and 25 nM, respectively. The developed fluorescence method using NCBs for oligonucleotide sequence detection was sensitive, facile and had potential for use in bioanalysis and diagnosis.

    更新日期:2020-01-13
  • In situ green synthesis of highly fluorescent Fe2O3@CQD/graphene oxide using hard pistachio shells via the hydrothermal‐assisted ball milling method
    Luminescence (IF 1.691) Pub Date : 2020-01-09
    Fatemeh Abdolrezaei; Mohammad Sabet

    In this study, highly photoluminescent and photocatalytic Fe2O3@carbon quantum dots/graphene oxide nanostructures were synthesized using ball milling‐assisted hydrothermal synthesis with hard pistachio shells. Different analyses, such as X‐ray diffraction, energy dispersive X‐ray spectroscopy, and Fourier transform infrared spectroscopy were used to study the product structure. Scanning electron microscopy and transmission electron microscopy images were used to study product size and morphology. Optical properties of the as‐synthesized nanomaterials were investigated using ultraviolet–visible light and photoluminescence analyses. To increase photoluminescence intensity, ethylene diamine tetraacetic acid, polyethylene glycol, polyvinylpyrrolidone, and acetylacetonate anions were used to modify the product surface. Thermal stability of the product was studied using thermal gravimetric analysis. Finally, photocatalytic activity and surface adsorption of the product were investigated; the produce was found to be highly photoluminescent with high photocatalytic and surface activities.

    更新日期:2020-01-10
  • Novel spectrofluorimetric quantification of linagliptin in biological fluids exploiting its interaction with 4‐chloro‐7‐nitrobenzofurazan
    Luminescence (IF 1.691) Pub Date : 2020-01-09
    Heba A. Aref; Sherin F. Hammad; Mohamed Saleh Elgawish; Khaled M. Darwish

    Direct determination of linagliptin (LIN) using fluorimetry has been limited because LIN releases a very weak fluorescence signal. Accordingly, it should be derivatized first with a fluorogenic reagent to enhance its fluorescence and consequentially the sensitivity required for its bioanalysis. This is the first description of a spectrofluorimetric method for LIN quantification in human plasma. The suggested method exploits the nucleophilic nature of its amino group to react with 4‐chloro‐7‐nitrobenzofurazan (NBD‐Cl) in borate buffer at pH 8.5 to yield a strong fluorescent product with excitation and emission wavelengths of 459 and 529 nm, respectively. Experimental variables concerning the conditions of reaction and fluorescence intensity were carefully investigated and optimized. The linearity range was from 1.0–100 ng ml−1 with a lower detection limit and a lower quantification limit of 0.60 ng ml−1 and 1.82 ng ml−1, respectively. Validation of the suggested method has been accomplished and the application to LIN analysis in commercial tablets as well as in human plasma resulted in a mean per cent recovery of 100.12 ± 1.57 and 99.65 ± 1.22, respectively. The developed method was proven to be a promising, simple and fast alternative bioanalytical method for LIN quantification in clinical and bioequivalence research.

    更新日期:2020-01-10
  • Spatial energy transfer with observation of bimolecular singlet oxygen emission using quantum dots as donors and zinc‐phthalocyanine as acceptors
    Luminescence (IF 1.691) Pub Date : 2020-01-08
    Adamo F. G. Monte; Guilherme Azevedo; Arnaldo F. Reis

    This study reports the influence of CdSe–ZnS core–shell quantum dots (QDs) for formation of singlet oxygen using zinc‐phthalocyanine (ZnPc) dyes in colloidal solutions. Using a microluminescence surface scan technique it was possible to measure accurately the photon diffusion length, or photon mean free path, inside the medium. Analyses were performed for a range of QD concentrations. Photon diffusion length was assigned to the bimolecular singlet oxygen emission at 707 nm. Related singlet oxygen emission was predicted by observing quenching of the photon diffusion length measured at the specific oxygen emission as a function of QD concentration, being a nontrivial phenomenon related to the QD donors. Diffusion length measured at 707 nm increased with QD concentration; in the absence of QDs, as in pure ZnPc samples, the emission peak at 707 nm was not observed.

    更新日期:2020-01-09
  • Synthesis and photophysical studies on a new fluorescent phenothiazine‐based derivative
    Luminescence (IF 1.691) Pub Date : 2020-01-08
    Fatimah A.M. Al‐Zahrani; Khloud Abu Mellah; Reda M. El‐Shishtawy; Amerah M. Al‐Soliemy; Abdullah M. Asiri

    A new typical phenothiazine compound functionalized with thienyl‐indandione derivative (PTZTID) was synthesized and characterized using spectral analysis (ultraviolet–visible (UV–vis) light, infrared (IR), 1H nuclear magnetic resonance (NMR) and 13C NMR tools). The UV–vis absorption spectra of the PTZTID solution in 1,4‐dioxane showed two absorption bands attributed to localized aromatic π–π* transitions of conjugated aromatic moieties and intramolecular charge transfer with the characteristics of a π–π* transition. The fluorescence spectra exhibited a maximum emission wavelength at 580 nm. The effect of concentration on photophysical properties took the form of a minor hypsochromic shift, which was attributed to some extent to the occurrence of H‐type aggregation of the PTZTID derivative. Binary solvent effects on the spectroscopic behaviour of PTZTID were measured at different H2O/1,4‐dioxane ratios. Similarly, when increasing the water content, a hypsochromic shift was observed that resulted from H‐type aggregation. Furthermore, geometry and electronic configurations of PTZTID were studied at density functional theory /B3LYP level and indicated that the compound had a nonplanar (butterfly structure).

    更新日期:2020-01-09
  • A turn‐on luminescence probe for highly selective detection of an anthrax biomarker
    Luminescence (IF 1.691) Pub Date : 2020-01-08
    Xiao Liu; Dong Chen; Chenchen Wang; Nianjuan Tian; Zhiqiang Li; Ying Zhang; Zhi‐Jun Ding

    Highly selective detection of Bacillus anthrax spores has attracted worldwide attention because Bacillus anthrax spores not only are harmful to the health of human beings and animals, but also can be used as biological warfare agents. Here, we report a simple platform by mixing EuCl3·6H2O and sodium polyacrylate in aqueous solution and further investigate its luminescence response towards Bacillus anthrax biomarker dipicolinic acid (DPA) as a turn‐on luminescence probe. Importantly, our probe has good sensitivity, lower detection limit, excellent selectivity as well as great anti‐interference ability due to the great luminescence enhancement of Eu3+. Moreover, a test paper is constructed to realize the purpose of portable detection. These results indicate that our probe is an excellent candidate for sensing DPA.

    更新日期:2020-01-09
  • Intense green‐, red‐emitting Tb3+, Tb3+/Bi3+‐doped and Sm3+, Sm3+/La3+‐doped Ca2Al2SiO7 phosphors
    Luminescence (IF 1.691) Pub Date : 2020-01-07
    V.B. Pawade; R.L. Kohale; D.A. Ovhal; N.S. Dhoble; S.J. Dhoble

    This paper focuses on an optical study of a Tb3+/Bi3+‐doped and Sm3+/La3+‐ doped Ca2Al2SiO7 phosphor synthesized using combustion methods. Here, Ca2Al2SiO7:Sm3+ showed a red emission band under visible light excitation but, when it co‐doped with La3+ ions, the emission intensity was further enhanced. Ca2Al2SiO7:Tb3+ shows the characteristic green emission band under near‐ultraviolet light excitation wavelengths, co‐doping with Bi3+ ions produced enhanced photoluminescence intensity with better colour tunable properties. The phosphor exhibited better phase purity and crystallinity, confirmed by X‐ray diffraction. Binding energies of Ca(2p), Al(2p), Si(2p), O(1s) were studied using X‐ray photoelectron spectroscopy. The reported phosphor may be a promising visible light excited red phosphor for light‐emitting diodes and energy conversion devices.

    更新日期:2020-01-08
  • Solvent‐dependent ultrafast optical response of conjugated push–pull chromophores
    Luminescence (IF 1.691) Pub Date : 2020-01-07
    Ying Chen; Ran Lu; WenYan Wang; Quan Wang; Xiao‐Chun Chi; Han‐Zhuang Zhang

    Two new difluoroboron β‐carbonyl cyclic ketonate complexes C2B and DC2B were investigated using several spectroscopic methods. Relative to the absorption spectra, the fluorescence spectra were more affected by the polarity of the solvent. Also, compound C2B showed a more pronounced Stokes’ shift after solvent polarity increased. Transient absorption measurements then demonstrated the relaxation behaviour of the excited state compound molecule. The kinetic results showed that the excited state C2B in tetrahydrofuran (THF) can return from the intramolecular charge‐transfer (ICT) state and the initial excited state to the ground state. The kinetic relaxation pathway after THF was replaced by dimethyl sulfoxide became single. When the carbazole unit was introduced, DC2B also exhibited an ICT state but there was no significant difference in the excited state relaxation path after solvent polarity was changed. The results indicated that C2B is more susceptible to solvent polarity regulation. The global fit results revealed that an increase in the solvent polarity prolonged the lifetime of the ICT state of compound C2B and had the opposite effect on compound DC2B. These results provide guidance for understanding the relationship between solvent polarity and the designing and synthesizing advanced compound materials.

    更新日期:2020-01-07
  • Synchronous spectrofluorometric methods for simultaneous determination of diphenhydramine and ibuprofen or phenylephrine in combined pharmaceutical preparations
    Luminescence (IF 1.691) Pub Date : 2020-01-06
    Aya Saad Radwan; Mohamed M. Salim; Sherin F. Hammad

    Simple and rapid synchronous fluorometric methods were adopted and validated for the simultaneous analysis of a binary mixture of diphenhydramine (DIP) and ibuprofen (IBU) (Mix I) or DIP and phenylephrine (PHE) (Mix II) in their co‐formulated pharmaceuticals without prior separation. Analysis of Mix I is based on the measurement of the peak amplitudes (D1) of synchronous fluorescence intensities at 265.1 nm for DIP and 260 nm for IBU. The relationship between the concentration and the amplitude of the first‐derivative synchronous fluorescence spectra showed good linearity over the concentration ranges 0.50–10.00 μg ml−1 and 0.50–7.90 μg ml−1 for DIP and IBU, respectively. Analysis of Mix II was based on measurement of the peak amplitude (D1) synchronous fluorescence intensities at 230 nm for DIP and at 253.9 nm for PHE. Moreover, for Mix II, the peak amplitude (D2) synchronous fluorescence intensities were measured at 227.9 nm for DIP and at 264.9 nm for PHE. Calibration plots were rectilinear over the concentration range 0.30–3.50 μg ml−1 and 0.03–0.75 μg ml−1 for DIP and PHE, respectively. The proposed methods were successfully applied to determine the studied compounds in pure form and in pharmaceutical preparations.

    更新日期:2020-01-06
  • Photoluminescence and piezoelectric behaviour of Y2Zr2O7 pyrochlore‐based multifunctional materials and the influence of Eu3+ and Sm3+
    Luminescence (IF 1.691) Pub Date : 2020-01-05
    Esra Öztürk; Erkul Karacaoglu; Volkan Kalem

    Y2Zr2O7‐doped with Eu3+ and Sm3+ phosphors were prepared for the first time as multifunctional smart materials using a solid‐state reaction method at 1400oC. Thermal behaviour, crystal structure, surface morphology, and elemental analysis were characterized using thermogravimetric (TG) and differential thermal (DTA) analyses, X‐ray diffraction (XRD) and scanning electron microscope equipped with energy‐dispersive X‐ray spectroscopy (SEM‐EDX). Experimental results revealed that both phosphors have a pyrochlore structure with a cubic crystal system. Photoluminescence properties were also measured and red emission was observed from Y1.90Eu0.10Zr2O7 and Y1.90Sm0.10Zr2O7 phosphors. Dielectric constant, loss tangent, piezoelectric charge constant, and Curie temperature of all the samples were determined using an LCR‐meter, d33‐meter, and TG/DTA. Eu doping in Y2Zr2O7 resulted in a high dielectric constant (9.61) and low loss tangent (1.67%) values, whereas high piezoelectric charge constant (0.68 pC/N) and high Curie temperature (820°C) could be obtained using Sm‐doped Y2Zr2O7.

    更新日期:2020-01-06
  • Chemiluminescence of 3‐aminophthalic acid anion–hydrogen peroxide–cobalt (II)
    Luminescence (IF 1.691) Pub Date : 2020-01-03
    Kai Huang; Yonghua Sun; Lin Liu; Chaoyu Hu

    The 3‐aminophthalic acid anion is a light emitter in luminol chemiluminescence. In the present study, the chemiluminescence of the 3‐aminophthalic acid anion itself in the presence of hydrogen peroxide–cobalt (II) was studied. The results indicated that 3‐aminophthalic acid anion is highly chemiluminescent in the typical hydrogen peroxide–cobalt (II) system. The peak wavelength of this chemiluminescence and the kinetic profile of the 3‐aminophthalic acid anion–hydrogen peroxide–cobalt (II) reaction showed similarity with that of luminol, but the chemiluminescence of 3‐aminophthalic acid anion had a much lower background signal. In addition, the chemiluminescence mechanism of 3‐aminophthalic acid anion–hydrogen peroxide–cobalt (II) was also discussed and speculated as the interaction between 3‐aminophthalic acid anion and singlet oxygen.

    更新日期:2020-01-04
  • Multiway data analysis approach toward understanding of photoluminescence and energy transfer in carbon nanodots
    Luminescence (IF 1.691) Pub Date : 2020-01-02
    Saeed Bagheri; Mohsen Kompany‐Zareh; Touraj Karimpour

    In this study, dilution analysis and anion exchange chromatography (AEC) were employed to provide insights into the photoluminescence (PL) of carbon nanodots (CNDs). A stepwise dilution process revealed that some of the fluorophores with higher energy emission were quenched in the high concentration solution and appeared in the dilute solutions. AEC fractionation led to seven sorts of CND fractions with similar surface charges. The fractionation for this CND mixture showed that excitation wavelength dependence was lower for separated CND particles. The wavelength dependence of excitation spectra could be due to energy exchange between particles that was reduced in diluted solutions and separated fractions. Multivariate analysis of AEC's data demonstrated that there were five distinct fluorophores, which formed the total CND emission. It is interesting that none of these fluorophores had a clear contribution to the surface charge of the CND particles. Further characterization through FTIR spectroscopy and 1H NMR revealed that optical properties of CNDs did not follow the surface functional groups in CNDs. This situation means that the optical behaviour of particles and their fluorophores differed depending on the surface functional groups.

    更新日期:2020-01-04
  • Molten salt synthesis and luminescence of Dy3+‐doped Y3Al5O12 phosphors
    Luminescence (IF 1.691) Pub Date : 2020-01-02
    Yu‐Guo Yang; Xu‐Ping Wang; Bing Liu; Yuan‐Yuan Zhang; Xian‐Shun Lv; Jing Li; Lei Wei; Hua‐Jian Yu; Yanyan Hu; Hua‐Di Zhang

    Dy3+‐doped Y3Al5O12 phosphors were prepared at a relatively low temperature using molten salt synthesis. The phase of the prepared Dy3+‐doped Y3Al5O12 phosphors was confirmed using X‐ray powder diffraction. Results indicated that Dy3+ doping did not change the Y3Al5O12 phase. Following excitation at 352 nm, emission spectra of the Dy3+‐doped Y3Al5O12 phosphors consisted of blue, yellow, and red emission bands. The influence of Dy3+ concentration and excitation wavelength on emission was investigated. The ratio of yellow light to blue light varied with change in Dy3+ doping concentration, due to changes in the structure around Dy3+. Emission intensities also changed when the excitation wavelength was changed. This variation is luminescence generated a system for tunable white light for Dy3+‐doped Y3Al5O12 phosphors.

    更新日期:2020-01-04
  • Redox‐modulated colorimetric detection of ascorbic acid and alkaline phosphatase activity with gold nanoparticles
    Luminescence (IF 1.691) Pub Date : 2020-01-02
    Liping Lin; Yaxin Luo; Qiushuang Chen; Qingjiao Lai; Qiaoling Zheng

    Gold nanoparticles (AuNPs) exhibit characteristic absorption peaks in the ultraviolet visible region due to their special surface plasmon resonance effect. This characteristic absorption peak would change with the relative colour varying from wine red to orange‐yellow upon sequential addition of ascorbic acid (AA) into the mixture of AuNPs and Ag(I). Similar observations also could be found when the hydrolysis product of sodium l‐ascorbyl‐2‐phosphate with alkaline phosphatase (ALP) was used as an alternative to AA. Results of structure characterization confirmed that the phenomena were due to the reduction of Ag(I) to Ag(0) on the surface of AuNPs and the formation of core‐shell AuNPs@Ag. Therefore, a colorimetric assay for rapid visual detection of AA and ALP based on redox‐modulated silver deposition on AuNPs has been proposed. Under the optimal experimental conditions, the absorbance variation ΔA522 nm/A370 nm of AuNPs was proportional to the concentration of AA (5–60 μmol/L) and ALP (3–18 U/L) with the corresponding detection limit of 2.44 μmol/L for AA and 0.52 U/L for ALP. The assay showed excellent selectivity towards AA and ALP. Moreover, the assay has been applied to detect AA and ALP activity in real samples with satisfying results.

    更新日期:2020-01-04
  • Exploring the interactions of a Tb(III)–quercetin complex with serum albumins (HSA and BSA): spectroscopic and molecular docking studies
    Luminescence (IF 1.691) Pub Date : 2019-12-28
    Masoomeh Shaghaghi; Samaneh Rashtbari; Samira Vejdani; Gholamreza Dehghan; Abolghasem Jouyban; Reza Yekta

    Serum albumins (human serum albumin (HSA) and bovine serum albumin (BSA), two main circulatory proteins), are globular and monomeric macromolecules in plasma that transport many drugs and compounds. In the present study, we investigated the interactions of the Tb(III)–quercetin (Tb–QUE) complex with HSA and BSA using common spectroscopic techniques and a molecular docking study. Fluorescence data revealed that the inherent fluorescence emission of HSA and BSA was markedly quenched by the Tb–QUE complex through a static quenching mechanism, confirming stable complex formation (a ground‐state association) between albumins and Tb–QUE. Binding and thermodynamic parameters were obtained from the fluorescence spectra and the related equations at different temperatures under biological conditions. The binding constants (Kb) were calculated to be 0.8547 × 103 M−1 for HSA and 0.1363 × 103 M−1 for BSA at 298 K. Also, the number of binding sites (n) of the HSA/BSA–Tb–QUE systems was obtained to be approximately 1. Thermodynamic data calculations along with molecular docking results indicated that electrostatic interactions have a main role in the binding process of the Tb–QUE complex with HSA/BSA. Furthermore, molecular docking outputs revealed that the Tb–QUE complex has high affinity to bind to subdomain IIA of HSA and BSA. Binding distances (r) between HSA–Tb–QUE and BSA–Tb–QUE systems were also calculated using the Forster (fluorescence resonance energy transfer) method. It is expected that this study will provide a pathway for designing new compounds with multiple beneficial effects on human health from the phenolic compounds family such as the Tb–QUE complex.

    更新日期:2019-12-29
  • Depicting the binding of furazolidone/furacilin with DNA by multiple spectroscopies, voltammetric as well as molecular docking
    Luminescence (IF 1.691) Pub Date : 2019-12-28
    Shuyun Bi; Xiaoyue Sun; Xu Li; Rui Zhao; Di Shao

    The interaction between DNA and furazolidone/furacillin was investigated using various analytical techniques including spectroscopy and electroanalysis and molecular modelling. With the aid of acridine orange (AO), the fluorescence lifetimes of DNA–AO, DNA–furazolidone/furacillin–AO remained almost the same, which proved that the ground state complex was formed due to furazolidone/furacillin binding with DNA. Circular dichroism spectra and Fourier transform infrared spectroscopy showed that the second structure of DNA changed. Viscosity experiments presented that relative viscosity of DNA was increased with the increasing concentrations of furazolidone and almost unchanged for furacilin. In addition, the results of melting temperature (Tm), ionic strength, site competition experiments, cyclic voltammetry, and molecular docking all proved the intercalation binding mode for furazolidone and groove binding mode for furacilin. The binding constants (Ka) obtained from Wolfe–Shimmer equation were calculated as 3.66 × 104 L mol−1 and 3.95 × 104 L mol−1 for furazolidone–DNA and furacilin–DNA, respectively.

    更新日期:2019-12-29
  • Dosimetric features and kinetic parameters of a glass system dosimeter
    Luminescence (IF 1.691) Pub Date : 2019-12-28
    M.H.A. Mhareb; Y.S.M. Alajerami; Muna Alqahtani; Fatimh Alshahri; Noha Saleh; N. Alonizan; M. Maghrabi; S. Hashim; S.K. Ghoshal

    Lithium borate (LB) glasses doped with dysprosium oxide (Dy2O3) have been prepared by utilizing the conventional melt‐quench technique. The prepared glass samples were exposed to 60Co to check their dosimetric features and kinetic parameters. These features involve glow curves, annealing, fading, reproducibility, minimum detectable dose (MDD), and effective atomic number (Zeff). Kinetic parameters including the frequency factors and activation energy were also determined using three methods (glow curve analysis, initial rise, and peak shape method) and were thoroughly interpreted. In addition, the incorporation of Dy impurities into LB enhanced the thermoluminescence sensitivity ~170 times. The glow from LB:Dy appeared as a single prominent peak at 190°C. The best annealing proceeding was obtained at 300°C for 30 min. Signal stability was reported for a period of 1 and 3 months with a reduction of 26% and 31%, respectively. The proposed glass samples showed promising dosimeter properties that can be recommended for personal radiation monitoring.

    更新日期:2019-12-29
  • Deciphering binding mechanism between bovine serum albumin and new pyrazoline compound K4
    Luminescence (IF 1.691) Pub Date : 2019-12-27
    Ebru Bozkurt; Halise Inci Gul

    The binding mechanism of a new and possible drug candidate pyrazoline derivative compound K4 and bovine serum albumin (BSA) was investigated in buffer solution (pH 7.4) using ultraviolet–visible light absorption and steady‐state and synchronous fluorescence techniques. The fluorescence intensity of BSA was quenched in the presence of K4. The quenching process between BSA and K4 was examined at four different temperatures. Decrease of the quenching constants calculated using the Stern–Volmer equation and at increasing temperature suggested that the interaction BSA–K4 was realized through a static quenching mechanism. Synchronous fluorescence measurements suggested that K4 bounded to BSA at the tryptophan region. Fourier transform infrared spectroscopy results showed that there was no significant change in polarity around the tryptophan residue The forces responsible for the BSA–K4 interaction were examined using thermodynamic parameters. In this study, the calculated negative value of ΔG, the negative value of ΔH and the positive value of ΔS pointed to the interaction being through spontaneous and electrostatic interactions that were dominant for our cases. This study provides a very useful in vitro model to researchers by mimicking in vivo conditions to estimate interactions between a possible drug candidate or a drug and body proteins.

    更新日期:2019-12-29
  • Synthesis and activity of a coumarin‐based fluorescent probe for hydroxyl radical detection
    Luminescence (IF 1.691) Pub Date : 2019-12-26
    Bin Zhang; Lijing Xu; Yindi Zhou; Weijian Zhang; Yuanhong Wang; Yu Zhu

    As a type of reactive oxygen species (ROS), hydroxyl radical (·OH) is closely associated with many kinds of diseases. The present study aimed to develo p a novel OH fluorescent probe based on coumarin, a new compound that has not been previously reported. This probe exhibited good linear range and selectivity for ·OHl, and is able to avoid interference from some metal ions and other kinds of ROS (H2O2, O2.‐, 1O2, and HClO). Meanwhile, this probe has been used to evaluate the ·OH‐scavenging efficiency of different compounds, such as isopropyl alcohol, cytosine, uracil, Tempo, Glutathione (GSH), and dimethyl sulfoxide (DMSO). Therefore, the present study shows that this probe not only can effectively measure the level of ·OH, but also can assess the ·OH‐scavenging efficiency of different compounds. Furthermore this current study suggested that following further optimization, this probe may be potentially applied in the diagnosis of oxidative stress in human body.

    更新日期:2019-12-27
  • A Phenazine based colorimetric and fluorescent chemosensor for sequential detection of Ag+ and I− in aqueous media
    Luminescence (IF 1.691) Pub Date : 2019-12-23
    Pravin R. Dongare; Anil H. Gore; Govind B. Kolekar; Balu D. Ajalkar

    A new colorimetric and fluorescent probe MNTPZ based on 1H‐imidazo[4,5‐b]phenazine derivative has been designed and synthesized for successive detection of Ag+ and I−. The probe MNTPZ shows selective colorimetric response by a change in color from yellow to orange and “turn‐off” fluorometric response upon binding with Ag+ in DMSO: Water (pH = 7, 1:1, v/v) over other cations. The binding mode of probe MNTPZ to Ag+ was studied by Job's plot, 1H NMR studies, FT‐IR spectroscopy and DFT calculations. Moreover, the situ generated probe MNTPZ+ Ag+ complex acted as an efficient fluorometric “turn‐on” probe for I− via Ag+ displacement approach. The detection limit of probe MNTPZ for Ag+ and the resultant complex probe MNTPZ+ Ag+ for I− were determined to be 1.36 μmol/L and 1.03 μmol/L respectively. Notably, the developed probe was successfully used for quantitative determination of I− in real samples with satisfactory results.

    更新日期:2019-12-25
  • Three‐dimensional ring‐oven washing technique for a paper‐based immunodevice
    Luminescence (IF 1.691) Pub Date : 2019-12-23
    Weiru Chu; Ying Chen; Wei Liu; Liu Zhang; Xiaoyan Guo

    Washing is a standard step for enzyme‐linked immunosorbent assays (ELISA) performed on a paper‐based chip, in which nonspecific‐binding antibodies and antigens should be removed completely from the paper surface. In this study, a novel three‐dimensional (3D) washing strategy using a heating ring‐oven was carried out on a paper‐based chip. Compared with a plane washing mode by a ring‐oven, this 3D washing strategy obtained a lower background, as gravity played an important role in the washing step. The paper‐based chip was placed on a 3D plastic holder and the waste area was connected to a heating ring. Use of a heating waste area meant that the nonspecific‐binding protein was continuously carried to the waste area through gravity and capillary action. The angle between the plastic holder and the ring plane was carefully selected. The effect of washing on different parts of the detection area was investigated by upconversion fluorescence and chemiluminescence (CL). This novel 3D washing strategy was performed for carcinoembryonic antigen detection through CL and a lower detection limit of 2 pg ml−1 was obtained. This approach provides an effective washing strategy to remove nonspecific‐binding antibody from a paper‐based immunodevice.

    更新日期:2019-12-23
  • Effect of γ‐irradiation on thermal and thermoluminescence properties of polystyrene/europium (III) oxide composite film
    Luminescence (IF 1.691) Pub Date : 2019-12-23
    Shilpa Bhavsar; N.L. Singh; Birendra Singh

    In the present study, polystyrene:europium (III) oxide polymer films at a ratio of 95:5 wt% were prepared using a solution casting technique. These polymeric films were irradiated with 5, 25 and 50 kGy γ‐radiation doses and their thermoluminescence (TL) and thermal properties were studied as a function of radiation dose. Analysis of Fourier transform infrared spectra revealed different modes of vibration and polymer–filler interaction. Reduction of vibrational modes with radiation dose was observed. The TL glow curve intensity was observed to increase with increasing radiation dose and to become broader in the 378 K and 444 K regions. Detrapping of electrons implied by the glow curve was caused by thermally induced macromolecular motion, concurrent with β‐relaxation in polystyrene. The TL glow curve parameters were computed using a glow curve deconvolution method. Differential scanning calorimetry analysis indicated that the glass transition temperature (Tg) increased with increase in dose, suggesting crosslinking of the polymer chain. Scanning electron microscopy analysis evidenced the change in surface morphology due to γ‐irradiation.

    更新日期:2019-12-23
  • Micellar‐based spectrofluorimetric method for the selective determination of ledipasvir in the presence of sofosbuvir: application to dosage forms and human plasma
    Luminescence (IF 1.691) Pub Date : 2019-12-23
    Mohamed A. Abdel‐Lateef; Ramadan Ali; Mahmoud A. Omar; Sayed M. Derayea

    A fast, low‐cost, sensitive, and selective spectrofluorimetric method for the determination of ledipasvir was developed and validated. The method is based on an enhancement in the native fluorescence intensity of ledipasvir by 500% of its original value by the formation of hydrogen bonds between the cited drug and Tween‐20 in the micellar system (pH = 5.0). All fluorescence measurements were carried out at 425 nm and 340 nm for emission and excitation wavelengths, respectively. A linear relationship between the concentration of ledipasvir and the observed fluorescence intensity was achieved in the range of 0.1–2.0 μg ml−1 with 0.028, 0.084 μg ml−1, for detection and quantitation limits, respectively. The acquired selectivity and sensitivity using the proposed method facilitate the analysis of ledipasvir in spiked human plasma with sufficient percentage recovery (95.36–99.30%). The proposed method was developed and validated according to International Council for Harmonisation (ICH) guidelines. Moreover, the cited drug was successfully determined in its pharmaceutical dosage form using the proposed method. In addition, the validity of the proposed results was statistically confirmed using Student's t‐test, variance ratio F‐test, and interval hypothesis test.

    更新日期:2019-12-23
  • New bioluminescence pyrophosphate assay for high‐sensitivity detection of food‐borne pathogens
    Luminescence (IF 1.691) Pub Date : 2019-12-20
    Zhongjie Fei; Dongrui Zhou; Na Li; Pengfeng Xiao

    Traditional methods of identifying food‐borne pathogens are time consuming and laborious, so innovative methods for their rapid identification must be developed. Testing for bioluminescence pyrophosphate is a convenient and fast method of detecting pathogens without complex equipment. However, the sensitivity of the method is not as high as that of other methods, and it has a very high detection limit. In this study, the method was optimized to improve its sensitivity. The shortcomings of the method were first identified and corrected using dATPαS instead of dATP for the polymerase chain reaction (PCR), therefore reducing the background signal. Also, when the DNA template extracted from the food‐borne pathogens was purified, the new bioluminescence pyrophosphate assay had a limit of detection of <10 copy/μl or 10 colony‐forming units/ml, and its sensitivity was higher than that of fluorescent real‐time quantitative PCR. Moreover, a single copy of a food‐borne pathogen could be detected when a single DNA template was included in the PCR. Salmonella was detected in and isolated from 60 samples of broiler chicken, and the accuracy of the results was verified using a culture method (GB 4789.4–2010). These results showed that the new bioluminescence pyrophosphate assay has the advantages of an intuitive detection process, convenient operation, and rapid measurements. Therefore, it can be used for the rapid detection of pathogenic bacteria and probiotics in various fields.

    更新日期:2019-12-21
  • Effect of Bi3+ addition on the upconversion luminescence properties of NaYbF4:Er
    Luminescence (IF 1.691) Pub Date : 2019-12-19
    Sandeep K. Agarwalla; Priyanka Ruz; Jyotirmayee Mohanty; G. Sridhar; V. Sudarsan

    In this study, Bi3+ incorporation in NaYbF4:Er lattice and its influence on upconversion luminescence properties have been investigated in detail using techniques such as temperature‐dependent luminescence, Fourier transform infrared spectroscopy and X‐ray diffraction (XRD). The study was carried out to develop phosphors with improved upconversion luminescence. From photoluminescence and lifetime measurements it is inferred that luminescence intensity from NaYbF4:Er increases with Bi3+ addition. The sample containing 50 at.% Bi3+ ions exhibited optimum upconversion luminescence. Increased distance between Yb3+–Yb3+ and Er3+–Er3+ due to Bi3+ incorporation into the lattice and associated decrease in the extent of dipolar interaction/self‐quenching are responsible for increase in lifetime values and luminescence intensities from Er3+ ions. Incorporation of Bi3+ into NaYbF4:Er lattice reduced self‐quenching among Yb3+–Yb3+ions and this facilitated energy transfer from Yb3+ to Er3+. This situation also explains decrease in the extent of temperature‐assisted quenching of emission from thermally coupled 2H11/2 and 4S3/2 levels of Er3+. Based on Rietveld refinement of XRD patterns it was confirmed that a maximum of 10 at.% of Bi3+added was incorporated into the NaYbF4:Er lattice and the remaining complex co‐exists as a BiOF phase. These results are of significant interest in the area of development of phosphors based on Yb3+–Er3+ upconversion luminescence.

    更新日期:2019-12-20
  • A turn‐off fluorescence probe based on terpyridine for pH monitoring
    Luminescence (IF 1.691) Pub Date : 2019-12-19
    Xiangxue Zhuge; Jinyan Li; Yexin Li; Chunxue Yuan

    A new pH‐dependent fluorescence probe 2,8‐bis((E)‐4‐([2,2′:6′,2″‐terpyridin]‐4′‐yl)styryl)‐6H,12H‐5,11‐methanodibenzo[b,f][1,5]diazocine (TBPTP) based on Tröger's base (TB) bound to terpyridine was designed and synthesized. Photophysical properties and titration experiments of TBPTP were investigated by absorption and fluorescence spectroscopy. TBPTP exhibited high sensitivity in an acidic environment with the working pH range 7.2–2.5, especially having a good liner response to pH changes in the range 2.5–4.3, which suggested that TBPTP is a good candidate for pH monitoring.

    更新日期:2019-12-20
  • Development of long‐persistent photoluminescent epoxy resin immobilized with europium (II)‐doped strontium aluminate
    Luminescence (IF 1.691) Pub Date : 2019-12-19
    Tawfik A. Khattab; Mahmoud Abd El‐Aziz; Meram S. Abdelrahman; Manal El‐Zawahry; Samir Kamel

    A facile approach for possible industrial production of long‐persistent phosphorescence, continuing to emitting light for a long time period, smart cobbles were developed toward photoluminescent hard surfaces. The inorganic strontium aluminium oxide pigment doped with rare earth elements was added to a synthetic organic epoxy in the presence of polyamine as a hardener to make a phosphor‐loaded viscous fluid that can then be hardened in a few minutes. The transparency of the solid cobbles can be accomplished easily using homogeneous dispersion of the phosphor in the epoxy resin fluid before the addition of a hardener to avoid pigment aggregation. This pigment–epoxy formula can be easily applied industrially onto flagstones surfaces under ambient conditions. The photoluminescent cobblestones demonstrated an optimum excitation wavelength at 366 nm and an emission band at 521 nm with a long‐persistent phosphorescence cobble surface. The development of a translucent white colour under normal daylight, bright green under ultraviolet (UV) irradiation, bright white colour after 30 sec in the dark, and phosphorescent green colour after 75 min in the dark was indicated using Commission Internationale de l’Eclairage (CIE) Laboratory coloration measurements. The luminescent hard composite cobble exhibited a highly durable and reversible long‐persistent phosphorescence light. Photoluminescence, morphological, and hardness properties as well as the elemental composition of the prepared cobbles were explored.

    更新日期:2019-12-19
  • A simple and rapid spectrofluorometric determination of pomalidomide in spiked plasma and urine. Application to degradation studies
    Luminescence (IF 1.691) Pub Date : 2019-12-18
    Z. Aydoğmuş; E.M. Yılmaz; G. Yildiz

    A rapid and accurate spectrofluorimetric method for the determination of pomalidomide was developed and validated based on the measurement of its native fluorescence without the need for any derivatization and separation for the first time. The fluorescence intensity of the drug in acetonitrile solution allowed precise detection at 460 nm after excitation at 296 nm. The calibration curve was linear in the concentration range 31.0–500.0 ng/ml. Limit of detection and limit of quantification were found to be 8.04 and 24.36 ng/ml, respectively. Sensitive results allowed the drug to be detected with good recovery (75.46–109.72%) in human plasma and urine using the developed method. The proposed method was validated in terms of linearity, sensitivity, precision, accuracy, recovery, and stability parameters. Pomalidomide was subjected to degradation under various stress conditions (hydrolytic, oxidative and thermal) to demonstrate that the method was stable, indicating and identifying possible degradation products. In addition, the drug was exposed to electrochemical degradation using the chronoamperometry technique for the first time. Characterization of pomalidomide degradation products obtained because of oxidative degradation and electrochemical degradation was carried out using attenuated total reflection Fourier transform infrared spectroscopy, mass spectrometry and high performance liquid chromatography − mass spectrometry methods and possible structures were proposed.

    更新日期:2019-12-19
  • Long‐lived electrochemiluminescence of ruthenium (II) complexes/tri‐n‐propylamine in aqueous solutions
    Luminescence (IF 1.691) Pub Date : 2019-12-18
    Ming Zhou; Nianping Dan; Hong Wang

    Although the clinical use of immunoassays based on the oxidative‐reduction electrochemiluminescence (ECL) of tris(2,2′‐bipyridine)ruthenium (II)/tri‐n‐propylamine has been a great success, elucidation of the ECL generation mechanism still remains unsatisfactory. We report here our experimental observations of long‐lived luminescence that remains detectable for several seconds after termination of electrochemical heterogeneous oxidation. Long‐lived luminescence was observed in both a surfactant‐free buffer and a surfactant‐containing broadly used commercial buffer under different conditions. The slow decay of emission seems to have been unnoticed in previous ECL mechanistic studies. Within the frame of the reaction schemes so far proposed, its origin is inconclusively ascribed to the reductive‐oxidation process of ruthenium (II) complex, that is Ru(bpy)32+ → Ru(bpy)31+ → Ru(bpy)32+* → Ru(bpy)32+ with the involvement of the tri‐n‐propylamine‐derived radical cation. It is anticipated that long‐lived ECL will suggest a research approach to separate some homogeneous reactions from the complicated reaction system and therefore help to resolve the mechanistic mystery.

    更新日期:2019-12-19
  • Structural and optical properties of europium‐ and titanium‐doped Y2O3 nanoparticles
    Luminescence (IF 1.691) Pub Date : 2019-12-18
    Ísis F. Manali; Lucas C.V. Rodrigues; Adriano H. Braga; Douglas Galante; Verônica C. Teixeira

    Luminescent nanoparticles of Y2O3 doped with europium (Eu) and/or titanium (Ti) were synthesized using modified sol–gel routes. The crystalline cubic phase was confirmed using X‐ray powder diffraction (XRD). Particle morphology and size were evaluated using scanning and transmission electron microscopy. High‐resolution transmission electron microscopy showed that the synthesis method affected the average particle size and the Fourier transform of the images showed the lattice plane distances, indicating that the samples presented high crystallinity degree in accordance with the XRD pattern. The Ti valence was investigated using X‐ray absorption near edge spectroscopy and the tetravalent form was the dominant oxidizing state in the samples, mainly in Eu and Ti co‐doped Y2O3. Optical behaviour was investigated through X‐ray excited optical luminescence and photoluminescence under ultraviolet–visible (UV–vis) and vacuum ultraviolet (VUV) excitation. Results indicated that Eu3+ is the emitting centre in samples doped with only Eu and with both Eu and Ti with the 5D0→7F2 transition as the most intense, indicating Eu3+ in a noncentrosymmetric site. Finally, in the Eu,Ti‐doped Y2O3 system, Ti3+ (or TiIV) excitation was observed but no Ti emission was present, indicating a very efficient energy transfer process from Ti to Eu3+. These results can aid the development of efficient nanomaterials, activated using UV, VUV, or X‐rays.

    更新日期:2019-12-19
  • Eu3+–Eu2+‐doped xAl2O3–ySiO2 and xAl2O3–zMgO composites phosphors
    Luminescence (IF 1.691) Pub Date : 2019-12-17
    Qihuang Guo; YuHeng Wu; Yuansheng Wu; Lixin Yu; Zhenyu Gao; Jianlin Zhong; Yingxuan Zou

    In this paper, the Eu3+–Eu2+ (4%, molar ratio)‐doped xAl2O3–ySiO2 (x = 0–2.5, y = 1–5) and xAl2O3–zMgO (x = 0–1.5, z = 0–3) composites phosphors with different Al2O3 to SiO2 (A/S) and Al2O3 to MgO (A/M) ratios were prepared using a high‐temperature solid‐state reaction under air atmosphere. The effects of the A/S and A/M on luminescence properties, crystal structure, electron spin resonance, and Commission Internationale de l’Eclairage chromaticity coordinates of the samples were systematically analyzed. These results indicated that the different A/S and A/M ratios in the matrix effectively affected the crystal phase, degrees of self‐reduction of Eu3+, and led the relative emission intensity of Eu2+/Eu3+ to change and adjust.

    更新日期:2019-12-18
  • Microenvironment improvement protocol for the sensitive spectrofluorimetric determination of an hepatitis C virus antiviral (Simeprevir): application to human plasma
    Luminescence (IF 1.691) Pub Date : 2019-12-17
    Sayed M. Derayea; Mohamed A. El Hamd; Sayed Ali; Ebtihal Samir

    Simeprevir (SPV) is a powerful antihepatitis C virus agent that was newly introduced into the pharmaceutical market. We here established and validated an easy, simple, and sensitive spectrofluorimetric method for its estimation at λem 427 nm (λex 337 nm). The suggested procedure was based on two times enhancement in the original emission of SPV through modifying its microenvironment in buffered aqueous solution by adding Triton X‐100. The relationship between the concentration of SPV and the observed fluorescence intensity was linear in the range 0.06–1.0 μg ml−1 with a correlation coefficient of 0.9997. The limits of detection and quantitation were 21 and 64 ng ml−1, respectively. The present method was effectively applied to quantify SPV content in pharmaceutical tablets and human plasma spiked with the drug with no interference from tablet excipients or plasma components.

    更新日期:2019-12-18
  • Synthesis and photoluminescence properties of Eu3+‐activated Ba2Mg(PO4)2 phosphor
    Luminescence (IF 1.691) Pub Date : 2019-12-16
    S.K. Ramteke; N.S. Kokode; A.N. Yerpude; G.N. Nikhare; S.J. Dhoble

    In this paper, we have reported the photoluminescence (PL) properties of the Ba2Mg(PO4)2:Eu3+ phosphor synthesized using a wet chemical method. The preliminary scanning electron microscopy (SEM) investigation of the sample revealed irregular surface morphology with particle sizes in the 10–50 μm range. The strongest PL excitation peak was observed at 396 nm. The emission spectra indicated that this phosphor can be effectively excited by the 396 nm wavelength. Upon 396 nm excitation, the emission spectrum showed characteristics peaks located at 592 nm and 615 nm. These intense orange‐red emission peaks were obtained due to f→f transitions of Eu3+ ions. The emission peak at 592 nm is referred to as the magnetic dipole 5D0→7F1 transition and the emission peak at 615 nm corresponded to the electric dipole 5D0→7F2 transition of Eu3+. The Commission Internationale de l’Eclairage (CIE) coordinates of the Ba2Mg(PO4)2:Eu3+ phosphor were found to be (0.586, 0.412) for wavelength 592 nm and (0.680, 0.319) for wavelength 615 nm situated at the edge of the CIE diagram, indicating high colour purity of phosphors. Due to the high emission intensity and a good excitation profile, Eu3+‐doped Ba2Mg(PO4)2 phosphor may be a promising orange‐red phosphor candidate for solid‐state lighting applications.

    更新日期:2019-12-17
  • Nanographite‐based fluorescent biosensor for detecting microRNA using duplex‐specific nuclease‐assisted recycling
    Luminescence (IF 1.691) Pub Date : 2019-12-16
    Qizhi He; Huaiqing Luo; Lingli Chen; Jun Dong; Keke Chen; Yi Ning

    The development of a nanographite (NG)‐based fluorescent biosensor for detecting microRNA (miRNA) is reported. Duplex‐specific nuclease (DSN)‐assisted signal amplification was key to its function. In the absence of a target, with the assistance of p‐stacking interactions, the NG adsorbed the double carboxyfluorescein (FAM)‐labelled probe (DFP) whose surface was perfectly complementary to miRNA, leading to quenching of FAM fluorescence. In the presence of a target, double‐stranded DNA/RNA hybrids were repelled by the NG and fluorescence was restored. Meanwhile, the considerable increase in signal strength and sensitivity suggests DSN‐mediated target recycling as an application. The detection limit of the proposed biosensor for miRNA was 10 pmol/L; there was a linear correlation when the miRNA concentration ranged from 50 pmol/L to 5 nmol/L. Additionally, the method could distinguish let‐7b from most let‐7 miRNA family members and was successfully used in a sample assay. This biosensor is a novel and highly sensitive tool for miRNA detection and has great potential for biochemical research, disease diagnosis, and therapy.

    更新日期:2019-12-17
  • Exploration of highly selective fluorogenic ‘on–off’ chemosensor for H2PO4− ions: ICT‐based sensing and ATPase activity profiling
    Luminescence (IF 1.691) Pub Date : 2019-12-16
    Yogesh B. Wagh; Kundan C. Tayade; Anil Kuwar; Suban K. Sahoo; Mayank; Narinder Singh; Dipak S. Dalal

    Abstract

    更新日期:2019-12-17
  • Sensitive chemical sensor array based on nanozymes for discrimination of metal ions and teas
    Luminescence (IF 1.691) Pub Date : 2019-12-14
    Jiao Li; Qi Cheng; Hui Huang; Meini Li; Shujun Yan; Yongxin Li; Zhiyong Chang

    Tea, originating from China, is an important part of Chinese traditional culture. There are different qualities of and producing areas for tea on the market, therefore it is necessary to discriminate between teas in a fast and accurate way. In this study, a chemical sensor array based on nanozymes was developed to discriminate between different metal ions and teas. The indicators for the sensor array are three kinds of nanozymes mimicking laccase (Cu‐ATP, Cu‐ADP, Cu‐AMP). The as‐developed sensor array successfully discriminated 12 metal ions and the detection limit was as low as 0.01 μM. The as‐developed sensor array was also able to discriminate tea samples. Different kinds of tea samples appeared in different areas in the canonical score plot with different response patterns. Furthermore, in a blind experiment, we successfully discriminated 12 samples with a 100% accuracy. This sensor array integrates chemistry and food science together, realizing the simultaneous detection of several kinds of teas using a sensitive method. The as‐developed sensor array would have an application in the tea market and provide a fast and easy method to discriminate between teas.

    更新日期:2019-12-17
  • Soluble electron acceptors affect bioluminescence from Shewanella woodyi
    Luminescence (IF 1.691) Pub Date : 2019-12-12
    Allison L. Theberge; Sahar M. Alsabia; Christopher T. Mortensen; Anna G. Blair; Nina M. Wendel; Justin C. Biffinger

    Shewanella woodyi cultures were used to correlate bioluminescence intensity with changes in the electrochemical potential of a saltwater medium using soluble electron acceptors. A relationship between the concentration of NaNO3 or CoCl2 to bioluminescence intensity was confirmed using aerobic cultures of S. woodyi at 20°C with glucose as the sole carbon source. In general, increasing the concentration of nitrate or Co(II) reduced the bioluminescence per cell, with complete luminescence being repressed at ≥5 mM nitrate and ≥0.5 mM Co(II). Results from cell viability fluorescent staining concluded that increasing the concentration of Co(II) or nitrate did not affect the overall viability of the cells when compared with cultures lacking Co(II) or nitrate. These data show that potentials of <0.2 V vs Normal Hydrogen Electrode (NHE) repress the luminescence from the cells, but the exact mechanism is unclear. Our results indicated that the luminescence intensity from S. woodyi could be systematically reduced using these two soluble electron acceptors, making S. woodyi a potential model bacterium for whole‐cell luminescence bioelectrochemical sensor applications.

    更新日期:2019-12-13
  • Issue Information
    Luminescence (IF 1.691) Pub Date : 2019-12-09

    No abstract is available for this article.

    更新日期:2019-12-11
  • Cu‐doped quantum dots: a new class of near‐infrared emitting fluorophores for bioanalysis and bioimaging
    Luminescence (IF 1.691) Pub Date : 2019-07-11
    Chenghui Li, Peng Wu

    Transition metal ion‐doped quantum dots (QDs) exhibit unique optical and photophysical properties that offer significant advantages over undoped QDs, such as larger Stokes shift to avoid self‐absorption/energy transfer, longer excited‐state lifetimes, wider spectral window, and improved chemical and thermal stability. Among the doped QDs emitters, Cu is widely introduced into the doped QDs as novel, efficient, stable, and tunable optical materials that span a wide spectrum from blue to near‐infrared (NIR) light. Their unique physical and chemical characteristics enable the use of Cu‐doped QDs as NIR labels for bioanalysis and bioimaging. In this review, we discuss doping mechanisms and optical properties of Cu‐doped QDs that are capable of NIR emission. Applications of Cu‐doped QDs in in vitro biosensing and in in vivo bioimaging are highlighted. Moreover, a prospect of the future of Cu‐doped QDs for bioanalysis and bioimaging are also summarized.

    更新日期:2019-12-11
  • Dual emission carbon dots from carotenoids: Converting a single emission to dual emission
    Luminescence (IF 1.691) Pub Date : 2019-08-09
    Achyut Konwar, Ankita Deb, Archita Kar, Devasish Chowdhury

    Dual emission carbon dots have a high potential for use as fluorescence‐based sensors with higher selectivity and sensitivity. This study demonstrated the possibility of conversion of a biological molecular system with a single emission peak to a double emission carbon dots system. This report is the first to describe the synthesis of dual emission carbon dots by tuning the electronic environment of a conjugated system. Here we prepared carbon dots from a natural extract, from which carotenoids were used as a new source for carbon dots. Formation of the carbon dots was confirmed by images obtained under a transmission electron microscope as well as from a dynamic light scattering study. The prepared carbon dots system was characterized and its optical property was monitored. The study showed that, after irradiation with microwaves, the fluorescence intensity of the whole system changed, without any change in the original peak position of the carotenoid but with the appearance of an additional peak. A Fourier transform infrared study confirmed breaking of the conjugated system. When using ethylene glycol as a surface passivating agent added to these carotenoid carbon dots, the dual emission spectra became more distinct.

    更新日期:2019-12-11
  • Spectroscopic and computational exploration of hypoxanthine riboside interacting with plasma albumin
    Luminescence (IF 1.691) Pub Date : 2019-07-21
    Hua‐xin Zhang, Dan Zhou, Qing‐hua Xia

    Hypoxanthine riboside (HXR) is a nucleoside essential for wobble base pairs to translate the genetic code. In this work, an absorption and luminescence study showed that HXR and human serum albumin (HSA) formed a new complex through hydrogen bonds and van der Waals forces at ground state. Fluorescence probe experiments indicated that HXR entered the first subdomain of domain II in HSA and was fixed by amino acid residues in site I defined by Sudlow, and after competing with a known site marker. The recognition interaction featured negative ΔHϴ, ΔSϴ and ΔGϴ thermodynamic parameters. Fluorescence and circular dichroism spectra described the polarity of residues and α‐helix and β‐strand content changed because of HXR binding. The most rational structure for the HXR–HSA complex was recommended by the molecular docking method, in which the binding location, molecular orientation, adjacent amino acid residues, and hydrogen bonds were included. In addition, the influence of β‐cyclodextrin and some essential metal ions on the balance of the HSA–HXR system interaction was measured. The study gained comprehensive information on the transportation mechanism for HXR in blood, and was of great significance in understanding the theory of HXR biotransformation and in discussing its clinical in vivo half‐life.

    更新日期:2019-12-11
  • Study of luminescence properties of dysprosium‐doped CaAl12O19 phosphor for white light‐emitting diodes
    Luminescence (IF 1.691) Pub Date : 2019-07-04
    Kapil Dev, Anupam Selot, Govind B. Nair, Vijay L. Barai, Nitu Singh, Fozia Z. Haque, M. Aynyas, S. J. Dhoble

    Dy3+‐doped CaAl12O19 phosphors were synthesized utilizing a combustion method. Crystal structure and morphological examinations were performed respectively using X‐ray diffraction (XRD) and scanning electron microscopy (SEM) techniques to identify the phase and morphology of the synthesized samples. Fourier transform infrared spectroscopy (FTIR) estimations were carried out using the KBr method. Photoluminescence properties (excitation and emission) were recorded at room temperature. CaAl12O19:Dy3+ phosphor showed two emission peaks respectively under a 350‐nm excitation wavelength, centered at 477 nm and 573 nm. Dipole–dipole interaction via nonradiative energy shifting has been considered as the major cause of concentration quenching when Dy3+ concentration was more than 3 mol%. The CIE chromaticity coordinates positioned at (0.3185, 0.3580) for the CaAl12O19:0.03Dy3+ phosphor had a correlated color temperature (CCT) of 6057 K, which is situated in the cool white area. Existing results point out that the CaAl12O19:0.03Dy3+ phosphor could be a favorable candidate for use in white light‐emitting diodes (WLEDs).

    更新日期:2019-12-11
  • Insight into the interaction of benzothiazole tethered triazole analogues with human serum albumin: Spectroscopy and molecular docking approaches
    Luminescence (IF 1.691) Pub Date : 2019-07-17
    Priyanka Yadav, Jitendra Kumar Yadav, Arvind Kumar Dixit, Alka Agarwal, Satish Kumar Awasthi

    The interaction of four benzothiazole tethered triazole analogues (MS43, MS70, MS71, and MS78) with human serum albumin (HSA) was investigated using various spectroscopic techniques (ultraviolet–visible (UV–vis) light absorption, fluorescence, circular dichroism (CD), molecular docking and density functional theory (DFT) studies). Fluorescence quenching constants (~1012) revealed a static mode of quenching and binding constants (Kb ~104) indicating the strong affinity of these analogues for HSA. Further alteration in the secondary structure of HSA in the presence of these analogues was also confirmed by far UV–CD spectroscopy. The intensity loss in CD studied at 222 nm indicated an increase in random coil/β‐sheet conformations in the protein. Binding energy values (MS71 (−9.3 kcal mol−1), MS78 (−8.02 kcal mol−1), MS70 (−7.16 kcal mol−1) and MS43 (−6.81 kcal mol−1)) obtained from molecular docking revealed binding of these analogues with HSA. Molecular docking and DFT studies validated the experimental results, as these four analogues bind with HSA at site II through hydrogen bonding and hydrophobic interactions.

    更新日期:2019-12-11
  • A conformational switch‐based aptasensor for the chemiluminescence detection of microRNA
    Luminescence (IF 1.691) Pub Date : 2019-07-09
    Sheng Cai, Jiawei Ye, Abdu Ahmed Abdullah AL‐maskri, Lianli Sun, Su Zeng

    A simple microRNA (miRNA) aptasensor has been developed combining the conformational switch of a streptavidin aptamer and isothermal strand displacement amplification. In the presence of its target miRNA, the allosteric molecular beacon (aMB) probe immobilized on the plate can be ‘switched on' and release the streptavidin aptamer. At the same time, Klenow fragment (3′→5′ exo‐) is utilized to initiate DNA‐strand displacement, which starts the target recycling process. Based on the aptamer' high binding affinity and subsequent catalytic chemiluminescence (CL) detection, this CL strategy is highly specific in distinguishing mature miRNAs in same family. It exhibits a dynamic range of four orders of magnitude with a detection limit of 50 fM, and shows great potential for miRNA‐related clinical practices and biochemical research.

    更新日期:2019-12-11
  • The structure and luminescence properties of Mn2+/Eu2+/Er3+‐doped MgO‐Ga2O3‐SiO2 glasses and glass‐ceramics
    Luminescence (IF 1.691) Pub Date : 2019-07-21
    Zhenyu Gao, Lixin Yu, Xiaoqin Man, Jianlin Zhong, Qihuang Guo, Yingxuan Zou

    The MgO–Ga2O3–SiO2 glasses and glass‐ceramics samples doped with Eu2+/Mn2+/Er3+ and heated in reductive atmosphere were prepared by the sol–gel method. The structure, morphology and the luminescence properties were studied using X‐ray diffraction, high‐resolution transmission electron microscope, fluorescence spectra, and up‐conversion emission. The luminescence characteristics of doped ions could be influenced by temperature and matrix component. The characteristic emission of Mn2+, Eu2+ and Er3+ were seen and the energy transfer efficiency from Eu2+ to Mn2+ was enhanced as Mn2+ concentration was increased. In addition, the two‐photon process was determined for the Er3+‐doped samples.

    更新日期:2019-12-11
  • Photoluminescence imaging of europium (III)‐doped γ‐Al2O3 nanofiber structures
    Luminescence (IF 1.691) Pub Date : 2019-07-16
    So Jeong Park, Choong Kyun Rhee, Youngku Sohn

    Aluminium oxide (Al2O3) has widely been used for catalysts, insulators, and composite materials for diverse applications. Herein, we demonstrated if γ‐Al2O3 was useful as a luminescence support material for europium (Eu) (III) activator ion. The hydrothermal method and post‐thermal treatment at 800°C were employed to synthesize Eu(III)‐doped γ‐Al2O3 nanofibre structures. Luminescence characteristics of Eu(III) ions in Al2O3 matrix were fully understood by taking 2D and 3D‐photoluminescence imaging profiles. Various sharp emissions between 580 to 720 nm were assigned to the 5D0→7FJ (J = 0, 1, 2, 3, 4) transitions of Eu(III) activators. On the basis of X‐ray diffraction crystallography, Auger elemental mapping and the asymmetry ratio, Eu(III) ions were found to be well doped into the γ‐Al2O3 matrix at a low (1 mol%) doping level. A broad emission at 460 nm was substantially increased upon higher (2 mol%) Eu(III) doping due to defect creation. The first 3D photoluminescence imaging profiles highlight detailed understanding of emission characteristics of Eu(III) ions in Al oxide‐based phosphor materials and their potential applications.

    更新日期:2019-12-11
  • Synthesis and luminescence study of Eu3+‐doped SrYAl3O7 phosphor
    Luminescence (IF 1.691) Pub Date : 2019-07-11
    A.R. Kadam, S.J. Dhoble

    Rare‐earth ions play an important role in eco‐friendly solid‐state lighting for the lighting industry. In the present study we were interested in Eu3+ ion‐doped inorganic phosphors for near ultraviolet (UV) excited light‐emitting diode (LED) applications. Eu3+ ion‐activated SrYAl3O7 phosphors were prepared using a solution combustion route at 550°C. Photoluminescence characterization of SrYAl3O7:Eu3+ phosphors showed a 612 nm emission peak in the red region of the spectrum due to the 5D0→7F2 transition of Eu3+ ions under excitation at 395 nm in the near‐UV region and at the 466 nm blue excitation wavelength. These red and blue emissions are supported for white light generation for LED lighting. Structure, bonding between each element of the sample and morphology of the sample were analysed using X‐ray diffraction (XRD) and scanning electron microscopy (SEM), which showed that the samples were crystallized in a well known structure. The phosphor was irradiated with a 60Co‐γ (gamma) source at a dose rate of 7.2 kGy/h. Thermoluminescence (TL) studies of these Eu3+‐doped SrYAl3O7 phosphors were performed using a Nucleonix TL 1009I TL reader. Trapping parameters of this phosphor such as activation energy (E), order of kinetics (b) and frequency factor (s) were calculated using Chen's peak shape method, the initial rise method and Ilich's method.

    更新日期:2019-12-11
  • Simple ultrasensitive spectrofluorimetric method for determination of midodrine in its tablet form: Application to content uniformity testing
    Luminescence (IF 1.691) Pub Date : 2019-07-23
    Mahmoud A. Omar, Dalia M. Nagy, Monica E. Halim

    A novel, simple, sensitive method was developed for determining midodrine spectrofluorimetrically in both its raw pure form and its tablet form. This study is based on the native fluorescence of midodrine and discusses the optimum solvent used and the wavelength range. The presented method was then validated with respect to linearity, accuracy, precision, and limits of detection and quantitation. The constructed calibration curve showed a linear range of 0.1–2.0 μg/ml. The limit of detection and limit of quantitation values were 0.03 and 0.10 μg/ml respectively. Finally, content uniformity testing was applied according to the United States Pharmacopoeia by adapting the presented method.

    更新日期:2019-12-11
  • Experimental design of a simple medium for the bioluminescence of Aliivibrio fischeri and mathematical modelling for growth estimation
    Luminescence (IF 1.691) Pub Date : 2019-07-25
    Odette Castillo‐Gómez, Víctor M. Ramírez‐Rivera, Blondy B. Canto‐Canché, Ruby A. Valdez‐Ojeda

    Increasing numbers of studies are using Aliivibrio fischeri (A. fischeri), a marine bioluminescent bacterium as a model, however the culture medium used for its growth are complex and expensive. The objectives of this study were: (1) to evaluate the effect of yeast extract, tryptone, and NaCl to select a simple and inexpensive culture medium suitable for A. fischeri growth and bioluminescence induction; and (2) to compare the performance of mathematical models to predict the growth of A. fischeri. A fractional factorial design was performed to evaluate the effect of yeast extract, tryptone, and sodium chloride on the luminescence of A. fischeri. The result showed that sodium chloride is the most important factor, congruent with its inducer role in bioluminescence. The best medium for bioluminescence induction was selected through an optimization plot, this medium is inexpensive, and generates the same luminescence as commercial formulations. The estimation of A. fischeri growth at OD600 measurement was statistically analyzed. All evaluated models fitted the data adequately (r2 > 0.96). The nonlinear models Gompertz, Richards and logistic provided a lower variation and a better fit of the growth estimation (r2>0.99), showing that these mathematical models can be used for the accurate growth prediction of A. fischeri.

    更新日期:2019-12-11
  • Green synthesis of strontium nanoparticles self‐assembled in the presence of carboxymethyl cellulose: an in vivo imaging study
    Luminescence (IF 1.691) Pub Date : 2019-07-22
    Hojjat Samareh Fekri, Mehdi Ranjbar, Gholamreza Dehghan Noudeh, Nazanin Ziasistani

    Carboxymethyl cellulose (CMC) is one of the main derivatives of cellulose and is used as a drug carrier for hydrophobic and hydrophilic drugs, imaging in vivo, and biological applications. Encapsulation is a technology in which target compounds are coated with wall compounds to form microcapsules. This study reports a new chemical processing wet method for precipitation and encapsulation of strontium nanoparticles (Sr NPs) within CMC structures using a sonochemical method. Preparation parameters such as microwave power and irradiation time as well as morphology and particle size of Sr NPs were also investigated. Products were characterized by X‐ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and atomic force microscopy. In this study, CMC was used as a biological stabilizer in a retentive phase to encapsulate Sr NPs. For the first time, Sr NPs were synthesized using CMC in a cost‐effective, simple, fast, micellation‐assisted, ultrasound method. Sr NPs were encapsulated in green capping agent structures of either 1%, 2% or 3% weight to provide an efficient optical nanostructure with a high yield at wavelengths 200–700 nm for use in in vivo imaging studies.

    更新日期:2019-12-11
  • Eu3+‐tetrakis β‐diketonate complexes for solid‐state lighting application
    Luminescence (IF 1.691) Pub Date : 2019-07-25
    Camila M.B. Leite Silva, Airton G. Bispo‐Jr, Felipe S.M. Canisares, Shirley A. Castilho, Sergio A.M. Lima, Ana M. Pires

    Eu3+–β‐diketonate complexes are used, for example, in solid‐state lighting (SSL) or light‐converting molecular devices. However, their low emission quantum efficiency due to water molecules coordinated to Eu3+ and low photostability are still problems to be addressed. To overcome such challenges, we synthesized Eu3+ tetrakis complexes based on [Q][Eu(tfaa)4] and [Q][Eu(dbm)4] (Q1 = C26H56N+, Q2 = C19H42N+, and Q3 = C17H38N+), replacing the water molecules in the tris stoichiometry. The tetrakis β‐diketonates showed desirable thermal stability for SSL and, under excitation at 390 nm, they displayed the characteristic Eu3+ emission in the red spectral region. The quantum efficiencies of the dbm complexes achieved values as high as 51%, while the tfaa complexes exhibited lower quantum efficiencies (28–33%), but which were superior to those reported for the tris complexes. The structures were evaluated using the Sparkle/PM7 model and comparing the theoretical and the experimental Judd–Ofelt parameters. [Q1][Eu(dbm)4] was used to coat a near‐UV light‐emitting diode (LED), producing a red‐emitting LED prototype that featured the characteristic emission spectrum of [Q1][Eu(dbm)4]. The emission intensity of this prototype decreased only 7% after 30 h, confirming its high photostability, which is a notable result considering Eu3+ complexes, making it a potential candidate for SSL.

    更新日期:2019-12-11
  • Probing the optical properties and luminescence mechanism of a UV‐emitting SrBPO5:Ce3+ phosphor
    Luminescence (IF 1.691) Pub Date : 2019-07-21
    Sitakanta Panda, P. Vinodkumar, U. Madhusoodanan, B.S. Panigrahi

    Ce‐doped (1 × 10−5 to 3.0 mol%) SrBPO5 phosphors were synthesized using a conventional solid‐state reaction route at 1273 K in an air atmosphere. Phase and morphology of the samples were studied from powder X‐ray diffraction (XRD) patterns and scanning electron microscope (SEM) micrographs, respectively. The band gap energies of the pure and Ce‐doped SrBPO5 phosphors were calculated from the recorded diffuse reflectance spectra. Photoluminescence (PL) and Ce3+ lifetime were recorded at 300 and 77 K. Photoluminescence lifetime measurements revealed two‐lifetime values for Ce3+ at both 300 K (17 and 36 nsec) and 77 K (12 and 30 nsec), suggesting the presence of two different environments around Ce3+. Time‐resolved emission spectroscopy (TRES) studies confirmed the presence of Ce3+ in two different environments. In addition, SrBPO5:Ce exhibited intense UV emission, signifying its possible use as an efficient sensitizer for solid‐state lighting applications. The effect of γ‐irradiation on PL was also determined. Thermally stimulated luminescence (TSL) glow curves of the γ‐irradiated phosphor, along with trap parameters, dose–response, and the possible TSL mechanism were also investigated. Positron annihilation lifetime spectroscopy was carried out to probe defects present in undoped and Ce‐doped SrBPO5.

    更新日期:2019-12-11
  • Development of sensitive benzofurazan‐based spectrometric methods for analysis of spectinomycin in vials and human biological samples
    Luminescence (IF 1.691) Pub Date : 2019-08-05
    Samiha A. Hussein, Baher I. Salman, Marwa F. B. Ali, Mostafa A. Marzouq

    Spectinomycin hydrochloride (SPEC) is an aminoglycoside antibiotic that has a broad spectrum against several bacterial strains of humans and veterinary infections. However, SPEC lacks a fluorophore or chromophore and this lack makes its analysis a challenge. Our study provides a simple, sensitive and low‐cost spectrofluorimetric/spectrophotometric method based on the reaction between secondary amine groups and a benzofurazan reagent using borate buffer (pH 9.2). The yielding compound was measured fluorimetrically at 530 nm (excitation at 460 nm) with colorimetry at 410 nm. The calibration curves ranged from 30 to 400 ng ml−1 and from 0.2 to 6 μg ml−1 for spectrofluorimetric and spectrophotometric analyses, respectively. The limits of detection were calculated to be 4.15 ng ml−1 and 0.05 μg ml−1 for spectrofluorimetric and spectrophotometric processes, respectively. The ultra‐affectability and high selectivity of the proposed method permitted analysis of SPEC in the dosage form and in human plasma samples, with good recoveries of about 101.19 and 97.11%, respectively, without any matrix interference. The proposed strategy was validated using International Conference on Harmonization standards and validated bioanalytically using USFDA recommendations.

    更新日期:2019-12-11
  • Rapid and visual detection for hypochlorite of an AIE enhanced fluorescence probe
    Luminescence (IF 1.691) Pub Date : 2019-07-30
    Huan‐ren Cheng, Yan Ji, Fei Liu, Xiao‐ju Lu

    In this paper, a new ‘turn‐on' fluorescence probe for the rapid, sensitive, and visual detection of hypochlorite is reported. The push–pull type trianiline–tricyanofuran‐based fluorescent probe was prepared using a condensation reaction between tricyanofuran and the thiophene–trianiline derivative that had high quantum yields and showed aggregation‐induced emission enhanced properties. Upon exposure to hypochlorite, prominent fluorescence enhancement of the probe was observed via the release of the fluorophore from the probe. The probe showed a ratiometric absorption change at 315 nm and 575 nm. Importantly, the probe showed an excellent detection limit for hypochlorite at 1.2 × 10−7 M in solution and it was successfully applied for monitoring hypochlorite in waste water by test strip. This work reports a new fluorescence analytical sensing method for hypochlorite that has potential practical value in environmental monitoring and biological discrimination.

    更新日期:2019-12-11
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