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Journal Cover Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
  [SJR: 0.628]   [H-I: 64]   [7 followers]  Follow
    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
   ISSN (Print) 1386-1425
   Published by Elsevier Homepage  [2969 journals]
  • Raman spectroscopy detection of biomolecules in biocrusts from differing
           environmental conditions
    • Abstract: Publication date: 15 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 171
      Author(s): I. Miralles, S.E. Jorge-Villar, B. van Wesemael, R. Lázaro
      Lichens and cyanobacteria colonize inhospitable places covering a wide climate range due to their different survival strategies, such as the synthesis of protective biomolecules. The effect of ecological factors on the synthesis of biomolecules has not been widely analysed. This study aimed to assess the effects of four factors (species, microclimate, seasonality and hydration state) and their interactions on the biomolecule frequency detected by Raman Spectroscopy. We included cyanobacterial biocrusts, and the lichens Diploschistes diacapsis, Squamarina lentigera, and Lepraria isidiata; two contrasted microclimates (typical and marginal), two contrasted seasons (hot and dry vs cool and wet) and two hydration states (dry and wet). “Species” was the most influential factor in the identity and frequency of the main biomolecules. Microclimatic differences in the range of the local specific habitats only influenced the biomolecules in cyanobacteria. There was a quadruple interaction among the factors, the effects being different mainly depending on the species. At D. diacapsis, the production of their main biomolecules depended on microclimate, although it also depended on seasonality. Nevertheless, in L. isidiata and S. lentigera microclimatic differences did not significantly affect the production of biomolecules. In the lichen species, the microhabitats exposed to relatively larger incident radiation did not show significantly larger relative frequency of photoprotective biomolecules. No clear connection between higher production of oxalates and drier microhabitats was found, suggesting that the synthesis of oxalates is not related to water reserve strategy. The pros and cons of monitor biomolecules in biocrust by Raman spectrometry were also discussed.
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      PubDate: 2016-07-27T09:19:09Z
       
  • Molecular characteristics of a fluorescent chemosensor for the recognition
           of ferric ion based on photoresponsive azobenzene derivative
    • Abstract: Publication date: 15 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 171
      Author(s): Zhen Chi, Xia Ran, Lili Shi, Jie Lou, Yanmin Kuang, Lijun Guo
      Metal ion recognition is of great significance in biological and environmental detection. So far, there is very few research related to the ferric ion sensing based on photoresponsive azobenzene derivatives. In this work, we report a highly selective fluorescent “turn-off” sensor for Fe3+ ions and the molecular sensing characteristics based on an azobenzene derivative, N-(3,4,5-octanoxyphenyl)-N′-4-[(4-hydroxyphenyl)azophenyl]1,3,4-oxadiazole (AOB-t8). The binding association constant was determined to be 6.07×103 M−1 in ethanol and the stoichiometry ratio of 2:2 was obtained from Job's plot and MS spectra. The AOB-t8 might be likely to form the dimer structure through the chelation of ferric ion with the azobenzene moiety. Meanwhile, it was found that the photoisomerization property of AOB-t8 was regulated by the binding with Fe3+. With the chelation of Fe3+, the regulated molecular rigidity and the perturbed of electronic state and molecular geometry was suggested to be responsible for the accelerated isomerization of AOB-t8 to UV irradiation and the increased fluorescence lifetime of both trans- and cis-AOB-t8-Fe(III). Moreover, the reversible sensing of AOB-t8 was successfully observed by releasing the iron ion from AOB-t8-Fe(III) with the addition of citric acid.
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      PubDate: 2016-07-27T09:19:09Z
       
  • Environment effect on spectral and charge distribution characteristics of
           some drugs of folate derivatives
    • Abstract: Publication date: 15 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 171
      Author(s): M. Khadem Sadigh, M.S. Zakerhamidi, S.M. Seyed Ahmadian, M. Johari-Ahar, L. Zare Haghighi
      Molecular surrounding media as an important factor can effect on the operation of wide variety of drugs. For more study in this paper, spectral properties of Methotrexate and Folinic acid have been studied in various solvents. Our results show that the photo-physical of solute molecules depend strongly on solute-solvent interactions and active groups in their chemical structures. In order to investigate the contribution of specific and nonspecific interactions on the various properties of drug molecules, the linear solvation energy relationships concept is used. Moreover, charge distribution characteristics of used samples with various resonance structures in solvent environments were calculated by means of solvatochromic method. The high value of dipole moments in excited state show that local intramolecular charge transfer can occur by excitation. These results about molecular interactions can be extended to biological systems and can indicate completely the behaviors of Methotrexate and Folinic acid in polar solvents such as water in body system.
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      PubDate: 2016-07-27T09:19:09Z
       
  • Cu(I) complexes of bis(methyl)(thia/selena) salen ligands: Synthesis,
           characterization, redox behavior and DNA binding studies
    • Abstract: Publication date: 15 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 171
      Author(s): Ashish K. Asatkar, Mamta Tripathi, Snigdha Panda, Rama Pande, Sanjio S. Zade
      Mononuclear cuprous complexes 1 and 2, [{CH3E(o-C6H4)CH=NCH2}2Cu]ClO4; E=S/Se, have been synthesized by the reaction of bis(methyl)(thia/selena) salen ligands and [Cu(CH3CN)4]ClO4. Both the products were characterized by elemental analysis, ESI-MS, FT-IR, 1H/13C/77Se NMR, and cyclic voltammetry. The complexes possess tetrahedral geometry around metal center with the N2S2/N2Se2 coordination core. Cyclic voltammograms of complexes 1 and 2 displayed reversible anodic waves at E 1/2 =+0.08V and +0.10V, respectively, corresponding to the Cu(I)/Cu(II) redox couple. DNA binding studies of both the complexes were performed applying absorbance, fluorescence and molecular docking techniques. Competitive binding experiment of complexes with ct-DNA against ethidium bromide is performed to predict the mode of binding. The results indicate the groove binding mode of complexes 1 and 2 to DNA. The binding constants revealed the strong binding affinity of complexes towards ct-DNA.
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      PubDate: 2016-07-27T09:19:09Z
       
  • Raman spectral characteristics of magmatic-contact metamorphic coals from
           Huainan Coalfield, China
    • Abstract: Publication date: 15 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 171
      Author(s): Shancheng Chen, Dun Wu, Guijian Liu, Ruoyu Sun
      Normal burial metamorphism of coal superimposed by magmatic-contact metamorphism makes the characteristics of the Raman spectrum of coal changed. Nine coal samples were chosen at a coal transect perpendicular to the intrusive dike, at the No. 3 coal seam, Zhuji Coal Mine, Huainan Coalfield, China, with different distances from dike-coal boundary (DCB). Geochemical (proximate and ultimate) analysis and mean random vitrinite reflectance (R 0, %) indicate that there is a significant relationship between the values of volatile matter and R 0 in metamorphosed coals. Raman spectra show that the graphite band (G band) becomes the major band but the disordered band (D band) disappears progressively, with the increase of metamorphic temperature in coals, showing that the structural organization in high-rank contact-metamorphosed coals is close to that of well-crystallized graphite. Evident relationships are observed between the calculated Raman spectral parameters and the peak metamorphic temperature, suggesting some spectral parameters have the potentials to be used as geothermometers for contact-metamorphic coals.
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      PubDate: 2016-07-27T09:19:09Z
       
  • Fluorescent probes based on side-chain chlorinated benzo[a]phenoxazinium
           chlorides: Studies of interaction with DNA
    • Abstract: Publication date: 15 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 171
      Author(s): B. Rama Raju, M. Sameiro T. Gonçalves, Paulo J.G. Coutinho
      The interaction of DNA with six water soluble benzo[a]phenoxazinium chlorides mono- or di-substituted with 3-chloropropyl groups at the O and N of 2- and 9-positions, along with methyl, hydroxyl and amine terminal groups at 5-positions, was investigated by photophysical techniques. The results indicated that almost all compounds intercalated in DNA base pairs at phosphate to dye ratio higher than 5. At lower values of this ratio, electrostatic binding mode with DNA was observed. Groove binding was detected mainly for the benzo[a]phenoxazinium dye with NH2·HBr terminal. The set of six benzo[a]phenoxazinium chlorides proved successful to label the migrating DNA in agarose gel electrophoresis assays. These finding proves the ability of these benzo[a]phenoxazinium dyes to strongly interact with DNA.
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      PubDate: 2016-07-27T09:19:09Z
       
  • Physicochemical aspects of the energetics of binding of sulphanilic acid
           with bovine serum albumin
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Tarlok S. Banipal, Amandeep Kaur, Parampaul K. Banipal
      The thermodynamic study of the binding of sulphanilic acid with model transport protein bovine serum albumin is a promising approach in the area of synthesizing new sulfa drugs with improved therapeutic effect. Thus, such binding studies play an important role in the rational drug design process. The binding between sulphanilic acid and bovine serum albumin has been studied using calorimetry, light scattering in combination with spectroscopic and microscopic techniques. The calorimetric data reveals the presence of two sequential nature of binding sites where the first binding site has stronger affinity (~104 M−1) and second binding site has weaker affinity (~103 M−1). However, the spectroscopic (absorption and fluorescence) results suggest the presence of single low affinity binding site (~103 M−1) on protein. The contribution of polar and non-polar interactions to the binding process has been explored in the presence of various additives. It is found that sulphanilic acid binds with high affinity at Sudlow site II and with low affinity at Sudlow site I of protein. Light scattering and circular dichroism measurements have been used to study the effect on the molecular topology and conformation of protein, respectively. Thus these studies provide important insights into the binding of sulphanilic acid with bovine serum albumin both quantitatively and qualitatively.
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      PubDate: 2016-07-27T09:19:09Z
       
  • Conformational study of melectin and antapin antimicrobial peptides in
           model membrane environments
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Lucie Kocourková, Pavlína Novotná, Sabína Čujová, Václav Čeřovský, Marie Urbanová, Vladimír Setnička
      Antimicrobial peptides have long been considered as promising compounds against drug-resistant pathogens. In this work, we studied the secondary structure of antimicrobial peptides melectin and antapin using electronic (ECD) and vibrational circular dichroism (VCD) spectroscopies that are sensitive to peptide secondary structures. The results from quantitative ECD spectral evaluation by Dichroweb and CDNN program and from the qualitative evaluation of the VCD spectra were compared. The antimicrobial activity of the selected peptides depends on their ability to adopt an amphipathic α-helical conformation on the surface of the bacterial membrane. Hence, solutions of different zwitterionic and negatively charged liposomes and micelles were used to mimic the eukaryotic and bacterial biological membranes. The results show a significant content of α-helical conformation in the solutions of negatively charged liposomes mimicking the bacterial membrane, thus correlating with the antimicrobial activity of the studied peptides. On the other hand in the solutions of zwitterionic liposomes used as models of the eukaryotic membranes, the fraction of α-helical conformation was lower, which corresponds with their moderate hemolytic activity.
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      PubDate: 2016-07-27T09:19:09Z
       
  • Structural and luminescent properties of KY(1−x)DyxBO3 phosphors
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Sowjanya G., Rama Moorthy L., Basavapoornima Ch., Jayasankar C.K.
      Yttrium borate phosphors (KY(1−x)DyxBO3) doped with Dy3+ ions were synthesized by the solid-state reaction method. The structural and morphological characteristics were studied by XRD, FTIR and SEM measurements. Luminescent properties of different concentrations of KY(1−x)DyxBO3 phosphors were investigated from the excitation, emission and decay analyses. The emission spectra exhibited characteristic blue (460–500nm) and yellow (555–610nm) bands of Dy3+ ions which combines to give white light. The evaluated color co-ordinates (x, y) were found to lie within the white light region of CIE chromaticity diagram. All the decay curves of Dy3+ ions exhibited non-exponential nature and the experimental lifetimes for the 4F9/2 excited level were found to decrease from 0.87, 0.47, 0.35, 0.26 and 0.13ms with the increase of Dy3+ ion concentrations from 0.05, 0.1, 0.15, 0.2 and 0.3mol%, respectively. In order to understand the energy transfer mechanism, the decay curves were fitted to Inokutti-Hirayama model and found that the energy transfer is of dipole-dipole type. From the results of these investigations, it is concluded that the KY(1−x)DyxBO3 phosphors are more useful for white light emitting diodes.
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      PubDate: 2016-07-27T09:19:09Z
       
  • Detection of herbicide effects on pigment composition and PSII
           photochemistry in Helianthus annuus by Raman spectroscopy and chlorophyll
           a fluorescence
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Petr Vítek, Kateřina Novotná, Petra Hodaňová, Barbora Rapantová, Karel Klem
      The effects of herbicides from three mode-of-action groups – inhibitors of protoporphyrinogen oxidase (carfentrazone-ethyl), inhibitors of carotenoid biosynthesis (mesotrione, clomazone, and diflufenican), and inhibitors of acetolactate synthase (amidosulfuron) – were studied in sunflower plants (Helianthus annuus). Raman spectroscopy, chlorophyll fluorescence (ChlF) imaging, and UV screening of ChlF were combined to evaluate changes in pigment composition, photosystem II (PSII) photochemistry, and non-photochemical quenching in plant leaves 6d after herbicide application. The Raman signals of phenolic compounds, carotenoids, and chlorophyll were evaluated and differences in their intensity ratios were observed. Strongly augmented relative content of phenolic compounds was observed in the case of amidosulfuron-treated plants, with a simultaneous decrease in the chlorophyll/carotenoid intensity ratio. The results were confirmed by in vivo measurement of flavonols using UV screening of ChlF. Herbicides from the group of carotenoid biosynthesis inhibitors significantly decreased both the maximum quantum efficiency of PSII and non-photochemical quenching as determined by ChlF. Resonance Raman imaging (mapping) data with high resolution (150,000–200,000 spectra) are presented, showing the distribution of carotenoids in H. annuus leaves treated by two of the herbicides acting as inhibitors of carotenoid biosynthesis (clomazone or diflufenican). Clear signs were observed that the treatment induced carotenoid depletion within sunflower leaves. The depletion spatial pattern registered differed depending on the type of herbicide applied.
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      PubDate: 2016-07-27T09:19:09Z
       
  • Novel organic NLO material bis(N-phenylbiguanidium(1+)) oxalate – A
           combined X-ray diffraction, DSC and vibrational spectroscopic study of its
           unique polymorphism
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Irena Matulková, Ivana Císařová, Přemysl Vaněk, Petr Němec, Ivan Němec
      Three polymorphic modifications of bis(N-phenylbiguanidium(1+)) oxalate are reported, and their characterization is discussed in this paper. The non-centrosymmetric bis(N-phenylbiguanidium(1+)) oxalate (I), which was obtained from an aqueous solution at 313K, belongs to the monoclinic space group Cc (a =6.2560(2)Å, b =18.6920(3)Å, c =18.2980(5)Å, β =96.249(1)°, V =2127.0(1)Å3, Z =4, R =0.0314 for 4738 observed reflections). The centrosymmetric bis(N-phenylbiguanidium(1+)) oxalate (II) was obtained from an aqueous solution at 298K and belongs to the monoclinic space group P21/n (a =6.1335(3)Å, b =11.7862(6)Å, c =14.5962(8)Å, β =95.728(2)°, V =1049.90(9)Å3, Z =4, R =0.0420 for 2396 observed reflections). The cooling of the centrosymmetric phase (II) leads to the formation of bis(N-phenylbiguanidium(1+)) oxalate (III) (a =6.1083(2)Å, b =11.3178(5)Å, c =14.9947(5)Å, β =93.151(2)°, V =1035.05(8)Å3, Z =4, R =0.0345 for 2367 observed reflections and a temperature of 110K), which also belongs to the monoclinic space group P21/n. The crystal structures of the three characterized phases are generally based on layers of isolated N-phenylbiguanidium(1+) cations separated by oxalate anions and interconnected with them by several types of N-H...O hydrogen bonds. The observed phases generally differ not only in their crystal packing but also in the lengths and characteristics of their hydrogen bonds. The thermal behaviour of the prepared compounds was studied using the DSC method in the temperature range from 90K up to a temperature near the melting point of each crystal. The bis(N-phenylbiguanidium(1+)) oxalate (II) crystals exhibit weak reversible thermal effects on the DSC curve at 147K (heating run). Further investigation of this effect, which was assigned to the isostructural phase transformation, was performed using FTIR, Raman spectroscopy and X-ray diffraction analysis in a wide temperature range.
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      PubDate: 2016-07-27T09:19:09Z
       
  • Solvatochromism and linear solvation energy relationship of the kinase
           inhibitor SKF86002
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Muhammad Khattab, Madeline Van Dongen, Feng Wang, Andrew H.A. Clayton
      We studied the spectroscopic characteristics of SKF86002, an anti-inflammatory and tyrosine kinase inhibitor drug candidate. Two conformers SKF86002A and SKF86002B are separated by energy barriers of 19.68kJ·mol−1 and 6.65kJ·mol−1 due to H-bonds, and produce the three major UV–Vis absorption bands at 325nm, 260nm and 210nm in cyclohexane solutions. This environment-sensitive fluorophore exhibited emission in the 400–500nm range with a marked response to changes in environment polarity. By using twenty-two solvents for the solvatochromism study, it was noticed that solvent polarity, represented by dielectric constant, was well correlated with the emission wavelength maxima of SKF86002. Thus, the SKF86002 fluorescence peak red shifted in aprotic solvents from 397.5nm in cyclohexane to 436nm in DMSO. While the emission maximum in hydrogen donating solvents ranged from 420nm in t-butanol to 446nm in N-methylformamide. Employing Lippert-Mataga, Bakhshiev and Kawski models, we found that one linear correlation provided a satisfactory description of polarity effect of 18 solvents on the spectral changes of SKF86002 with R 2 values 0.78, 0.80 and 0.80, respectively. Additionally, the multicomponent linear regression analysis of Kamlet-Taft (R 2 =0.94) revealed that solvent acidity, basicity and polarity accounted for 31%, 24% and 45% of solvent effects on SKF86002 emission, respectively. While Catalán correlation (R 2 =0.92) revealed that solvatochromic change of SKF86002 emission was attributed to changes in solvent dipolarity (71%), solvent polarity (12%), solvent acidity (11%) and solvent basicity (6%). Plot of Reichardt transition energies and emission energies of SKF86002 in 18 solvents showed also a linear correlation with R 2 =0.90. The dipole moment difference between excited and ground state was calculated to be 3.4–3.5debye.
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      PubDate: 2016-07-27T09:19:09Z
       
  • Fluorometric enzymatic assay of l-arginine
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Nataliya Stasyuk, Galina Gayda, Hasmik Yepremyan, Agnieszka Stepien, Mykhailo Gonchar
      The enzymes of l-arginine (further − Arg) metabolism are promising tools for elaboration of selective methods for quantitative Arg analysis. In our study we propose an enzymatic method for Arg assay based on fluorometric monitoring of ammonia, a final product of Arg splitting by human liver arginase I (further – arginase), isolated from the recombinant yeast strain, and commercial urease. The selective analysis of ammonia (at 415nm under excitation at 360nm) is based on reaction with o-phthalaldehyde (OPA) in the presence of sulfite in alkali medium: these conditions permit to avoid the reaction of OPA with any amino acid. A linearity range of the fluorometric arginase-urease-OPA method is from 100nM to 6μМ with a limit of detection of 34nM Arg. The method was used for the quantitative determination of Arg in the pooled sample of blood serum. The obtained results proved to be in a good correlation with the reference enzymatic method and literature data. The proposed arginase-urease-OPA method being sensitive, economical, selective and suitable for both routine and micro-volume formats, can be used in clinical diagnostics for the simultaneous determination of Arg as well as urea and ammonia in serum samples.
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      PubDate: 2016-07-27T09:19:09Z
       
  • A pyrene-based fluorescent sensor for ratiometric detection of heparin and
           its complex with heparin for reversed ratiometric detection of protamine
           in aqueous solution
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Weiwei Gong, Shihuai Wang, Yuting Wei, Liping Ding, Yu Fang
      An imidazolium-modified pyrene derivative, IPy, was used for ratiometric detection of heparin, and its complex with heparin was used for reversed ratiometric detection of protamine in both aqueous solution and serum samples. The cationic fluorescent probe could interact with anionic heparin via electrostatic interaction to bring about blue-to-green fluorescence changes as monomer emission significantly decreases and excimer increases. The binary combination of IPy and heparin could be further used for green-to-blue detection of protamine since heparin prefers to bind to protamine instead of the probe due to its stronger affinity with protamine. The cationic probe shows high sensitivity to heparin with a low detection limit of 8.5nM (153ng/mL) and its combination with heparin displays high sensitivity to protamine with a detection limit as low as 15.4nM (107.8ng/mL) according to the 3σ IUPAC criteria. Moreover, both sensing processes are fast and can be performed in serum solutions, indicating possibility for practical applications.
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      PubDate: 2016-07-27T09:19:09Z
       
  • High sensitivity and accuracy dissolved oxygen (DO) detection by using
           PtOEP/poly(MMA-co-TFEMA) sensing film
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Ke Zhang, Honglin Zhang, Ying Wang, Yanqing Tian, Jiupeng Zhao, Yao Li
      Fluorinated acrylate polymer has received great interest in recent years due to its extraordinary characteristics such as high oxygen permeability, good stability, low surface energy and refractive index. In this work, platinum octaethylporphyrin/poly(methylmethacrylate-co-trifluoroethyl methacrylate) (PtOEP/poly(MMA-co-TFEMA)) oxygen sensing film was prepared by the immobilizing of PtOEP in a poly(MMA-co-TFEMA) matrix and the technological readiness of optical properties was established based on the principle of luminescence quenching. It was found that the oxygen-sensing performance could be improved by optimizing the monomer ratio (MMA/TFEMA=1:1), tributylphosphate(TBP, 0.05mL) and PtOEP (5μg) content. Under this condition, the maximum quenching ratio I0/I100 of the oxygen sensing film is obtained to be about 8.16, Stern-Volmer equation is I0/I=1.003+2.663[O2] (R2 =0.999), exhibiting a linear relationship, good photo-stability, high sensitivity and accuracy. Finally, the synthesized PtOEP/poly(MMA-co-TFEMA) sensing film was used for DO detection in different water samples.


      PubDate: 2016-07-27T09:19:09Z
       
  • Editorial Board
    • Abstract: Publication date: 5 December 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 169




      PubDate: 2016-07-27T09:19:09Z
       
  • Absorption, fluorescence, and acid-base equilibria of rhodamines in
           micellar media of sodium dodecyl sulfate
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Elena N. Obukhova, Nikolay O. Mchedlov-Petrossyan, Natalya A. Vodolazkaya, Leonid D. Patsenker, Andrey O. Doroshenko, Andriy I. Marynin, Boris M. Krasovitskii
      Rhodamine dyes are widely used as molecular probes in different fields of science. The aim of this paper was to ascertain to what extent the structural peculiarities of the compounds influence their absorption, emission, and acid-base properties under unified conditions. The acid-base dissociation (HR+ ⇄R+H+) of a series of rhodamine dyes was studied in sodium n-dodecylsulfate micellar solutions. In this media, the form R exists as a zwitterion R±. The indices of apparent ionization constants of fifteen rhodamine cations HR+ with different substituents in the xanthene moiety vary within the range of pK a app =5.04 to 5.53. The distinct dependence of emission of rhodamines bound to micelles on pH of bulk water opens the possibility of using them as fluorescent interfacial acid–base indicators.
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      PubDate: 2016-07-19T14:19:17Z
       
  • Fluorimetric detection of Sn2+ ion in aqueous medium using Salicylaldehyde
           based nanoparticles and application to natural samples analysis
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Kishor S. Patil, Prasad G. Mahajan, Shivajirao R. Patil
      The fluorescent 2-[(E)-(2-phenylhydrazinylidene)methyl]phenol nanoparticles (PHPNPs) were prepared by a simple reprecipitation method. The prepared PHPNPs examined by Dynamic Light Scattering show narrower particle size distribution having an average particle size of 93.3nm. The Scanning Electron Microphotograph shows distinct spherical shaped morphology of nanoparticles. The blue shift in UV-absorption and fluorescence spectra of PHPNPs with respect to corresponding spectra of PHP in acetone solution indicates H- aggregates and Aggregation Induced Enhanced Emission (AIEE) for nanoparticles. The nanoparticles show selective tendency towards the recognition of Sn2+ ions by enhancing the fluorescence intensity preference to Cu2+, Fe3+, Fe2+, Ni2+, NH4 +, Ca2+, Pb2+, Hg2+ and Zn2+ ions, which actually seem to quench the fluorescence of nanoparticles. The studies on Langmuir adsorption plot, fluorescence lifetime of PHPNPs, DLS-Zeta sizer, UV–visible and fluorescence titration with and without Sn2+ helped to propose a suitable mechanism of fluorescence enhancement of nanoparticles by Sn2+ and their binding ability during complexation. The fluorescence enhancement effect of PHPNPs induced by Sn2+ is further used to develop an analytical method for detection of Sn2+ from aqueous medium in environmental samples.
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      PubDate: 2016-07-19T14:19:17Z
       
  • Optical properties and spectroscopic study of different modifier based
           Pr3+:LiFB glasses as optical amplifiers
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): A. Balakrishna, S. Babu, Vinod Kumar, O.M. Ntwaeaborwa, Y.C. Ratnakaram
      In this paper, we report the preparation and optical characterization of Pr3+ doped lithium fluoro borate (LiFB) glasses for six different chemical compositions of Li2B4O7-BaF2-NaF-MO (where M=Mg, Ca, Cd and Pb), Li2B4O7-BaF2-NaF-MgO-CaO and Li2B4O7-BaF2-NaF-CdO-PbO. The structural and optical properties of these glasses were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), optical absorption and photoluminescence techniques. The optical absorption spectra of Pr3+ ions in LiFB glasses have been recorded in the UV–VIS-NIR region. The optical absorption data are used to calculate various spectroscopic parameters such as Racah (E1, E2, E3) and spin-orbit interaction (ξ4f) parameters. Judd-Ofelt (J-O) (Ωλ where λ=2, 4 and 6) intensity parameters were determined by applying J-O theory, which in turn used to calculate the radiative properties such as radiative transition probabilities (A), radiative lifetimes (τR), integrated absorption cross-sections (Σ) and branching ratios (βr) for all emission levels of Pr3+ ion in different LiFB glass matrices. By using the J-O theory and luminescence parameters, stimulated emission cross sections (σp) of prominent transitions, 3P0 → 3H4 and 1D2 → 3H4 of Pr3+ ion in all LiFB glasses were calculated. 3P0 → 3H4 possesses higher branching ratios and stimulated emission cross-sections for the Pr3+:LiFB(Mg-Ca) glass, which can be used as a best laser excitation. The optical gain parameter (σpxτR) was noticed higher in Pr3+:LiFB(Mg-Ca) and Pr3+:LiFB(Cd-Pb) glasses for the transition 3P0→ 3H4 transition, and these glasses have potential for optical amplification at 488 nm wavelength.


      PubDate: 2016-07-19T14:19:17Z
       
  • LED based on alternating benzene-furan oligomers
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Senchuan Song, Jianghan Chen, Wenlong Pan, Hucacan Song, Huahong Shi, Yuliang Mai, Wu Wen
      A series of conjugated-chain compounds which contain two furan units and more than three other aromatic ring units were synthesized by two different methods, their UV–visible absorption coefficient (ε), maximum absorption wavelengths (λa), fluorescence emission wavelengths (λe), stokes shift and quantum yields (Φ) were determined, the relationships between the molecular structures and the effects of spectral behaviors were discussed. Meanwhile, the excitation spectrum and emission spectrum of 2b and 2d in solid and in ethyl acetate were respectively recorded, the thermal stability of 2b and 2d was evaluated, and the fluorescence emission behaviors of two light emitting diodes, fabricated with 2b and 2d as phosphors, were investigated. The results showed that most of target compounds can perform high fluorescence emission ability, compounds 2b and 2d can perform higher thermal stability under 350°C and they are suitable for making light emitting diode as phosphors, the light emitting diodes fabricated with 2b and 2d can show higher fluorescence emission ability. Therefore, those compounds are worthy of further being developed as fluorescent emission materials.
      Graphical abstract image

      PubDate: 2016-07-19T14:19:17Z
       
  • Firefly algorithm versus genetic algorithm as powerful variable selection
           tools and their effect on different multivariate calibration models in
           spectroscopy: A comparative study
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Khalid A.M. Attia, Mohammed W.I. Nassar, Mohamed B. El-Zeiny, Ahmed Serag
      For the first time, a new variable selection method based on swarm intelligence namely firefly algorithm is coupled with three different multivariate calibration models namely, concentration residual augmented classical least squares, artificial neural network and support vector regression in UV spectral data. A comparative study between the firefly algorithm and the well-known genetic algorithm was developed. The discussion revealed the superiority of using this new powerful algorithm over the well-known genetic algorithm. Moreover, different statistical tests were performed and no significant differences were found between all the models regarding their predictabilities. This ensures that simpler and faster models were obtained without any deterioration of the quality of the calibration.
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      PubDate: 2016-07-19T14:19:17Z
       
  • Simultaneous determination of umbelliferone and scopoletin in Tibetan
           medicine Saussurea laniceps and traditional Chinese medicine Radix
           angelicae pubescentis using excitation-emission matrix fluorescence
           coupled with second-order calibration method
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Li Wang, Hai-Long Wu, Xiao-Li Yin, Yong Hu, Hui-Wen Gu, Ru-Qin Yu
      A chemometrics-assisted excitation-emission matrix (EEM) fluorescence method is presented for simultaneous determination of umbelliferone and scopoletin in Tibetan medicine Saussurea laniceps (SL) and traditional Chinese medicine Radix angelicae pubescentis (RAP). Using the strategy of combining EEM fluorescence data with second-order calibration method based on the alternating trilinear decomposition (ATLD) algorithm, the simultaneous quantification of umbelliferone and scopoletin in the two different complex systems was achieved successfully, even in the presence of potential interferents. The pretreatment is simple due to the “second-order advantage” and the use of “mathematical separation” instead of awkward “physical or chemical separation”. Satisfactory results have been achieved with the limits of detection (LODs) of umbelliferone and scopoletin being 0.06ngmL−1 and 0.16ngmL−1, respectively. The average spike recoveries of umbelliferone and scopoletin are 98.8±4.3% and 102.5±3.3%, respectively. Besides, HPLC-DAD method was used to further validate the presented strategy, and t-test indicates that prediction results of the two methods have no significant differences. Satisfactory experimental results imply that our method is fast, low-cost and sensitive when compared with HPLC-DAD method.
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      PubDate: 2016-07-19T14:19:17Z
       
  • Surface plasmon resonance based selective and sensitive colorimetric
           determination of azithromycin using unmodified silver nanoparticles in
           pharmaceuticals and human plasma
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Vijay D. Chavada, Nejal M. Bhatt, Mallika Sanyal, Pranav S. Shrivastav
      In this article we report a novel method for colorimetric sensing and selective determination of a non-chromophoric drug-azithromycin, which lacks native absorbance in the UV–Visible region using unmodified silver nanoparticles (AgNPs). The citrate-capped AgNps dispersed in water afforded a bright yellow colour owing to the electrostatic repulsion between the particles due to the presence of negatively charged surface and showed surface plasmon resonance (SPR) band at 394nm. Addition of positively charged azithromycin at a concentration as low as 0.2μM induced rapid aggregation of AgNPs by neutralizing the negative charge on the particle surface. This phenomenon resulted in the colour change from bright yellow to purple which could be easily observed by the naked eye. This provided a simple platform for rapid determination of azithromycin based on colorimetric measurements. The factors affecting the colorimetric response like pH, volume of AgNPs suspension and incubation time were suitably optimized. The validated method was found to work efficiently in the established concentration range of 0.2–100.0μM using two different calibration models. The selectivity of the method was also evaluated by analysis of nanoparticles-aggregation response upon addition of several anions, cations and some commonly prescribed antibiotics. The method was successfully applied for the analysis of azithromycin in pharmaceuticals and spiked human plasma samples with good accuracy and precision. The simplicity, efficiency and cost-effectiveness of the method hold tremendous potential for the analysis of such non-chromophoric pharmaceuticals.
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      PubDate: 2016-07-19T14:19:17Z
       
  • Effect of quencher and temperature on fluorescence intensity of laser
           dyes: DETC and C504T
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Basavaraja Jana, S.R. Inamdar, Suresh Kumar H.M.
      Fluorescence quenching of 7- Diethylamino-3-thenoylcoumarin (DETC) and 2,3,6,7-tetrahydro-1,1,7,7-tetramethyl11-oxo-1H,5H,11H- [1]benzopyrano[6,7,8-ij]quinolizine-10-carboxylic acid, ethyl ester (C504T) by aniline(AN), dimethylaniline (DMA) and diethylaniline (DEA) was investigated in toluene by steady state and transient methods. The quenching parameters like frequency of encounter (k d), probability of quenching per encounter (p), quenching rate parameters (k q ) and activation energy of quenching (E a ) were determined experimentally. The k q values determined by steady state and time-resolved methods for the both dyes were found to be same, indicating the dynamic nature of interaction. Magnitudes of p and E a suggested that the quenching reaction is predominantly controlled by material diffusion. The quenching mechanism is rationalized in terms of electron transfer (ET) from donors (aromatic amines) to the acceptors (coumarin derivatives) confirmed by correlating k q with free energy changes (ΔG°). Further, an effect of temperature on fluorescence intensity was carried out in toluene and methanol solvents. Fluorescence intensity of both the dyes decreases with increase in temperature. Temperature quenching in case of C504T is due to intersystem crossing S1 →T2, whereas for DETC, quenching is due to intersystem crossing S1 →T2 and ICT→TICT transition.
      Graphical abstract image

      PubDate: 2016-07-19T14:19:17Z
       
  • The structural alteration and aggregation propensity of glycated lens
           crystallins in the presence of calcium: Importance of lens calcium
           homeostasis in development of diabetic cataracts
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Sara Zafaranchi ZM, Kazem Khoshaman, Raheleh Masoudi, Bahram Hemmateenejad, Reza Yousefi
      The imbalance of the calcium homeostasis in the lenticular tissues of diabetic patients is an important risk factor for development of cataract diseases. In the current study, the impact of elevated levels of calcium ions were investigated on structure and aggregation propensity of glycated lens crystallins using gel electrophoresis and spectroscopic assessments. The glycated proteins indicated significant resistance against calcium-induced structural insults and aggregation. While, glycated crystallins revealed an increased conformational stability; a slight instability was observed for these proteins upon interaction with calcium ions. Also, in the presence of calcium, the proteolytic pattern of native crystallins was altered and that of glycated protein counterparts remained almost unchanged. According to results of this study it is suggested that the structural alteration of lens crystallins upon glycation may significantly reduce their calcium buffering capacity in eye lenses. Therefore, under chronic hyperglycemia accumulation of this cataractogenic metal ion in the lenticular tissues may subsequently culminate in activation of different pathogenic pathways, leading to development of lens opacity and cataract diseases.
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      PubDate: 2016-07-19T14:19:17Z
       
  • Micelle assisted structural conversion with fluorescence modulation of
           benzophenanthridine alkaloids
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Ankur Bikash Pradhan, Sutanwi Bhuiya, Lucy Haque, Richa Tiwari, Suman Das
      In this study we have reported the anionic surfactant (Sodium dodecyl sulfate, SDS) driven structural conversion of two benzophenanthridine plant alkaloids namely Chelerythrine (herein after CHL) and Sanguinarine (herein after SANG). Both the alkaloids exist in two forms: the charged iminium and the neutral alkanolamine form. The iminium form is stable at low pH (<6.5) and the alkanolamine form exists at higher pH (>10.1). The fluorescence intensity of the alkanolamine form is much stronger than the iminium form. The iminium form of both the alkaloids remains stable whereas the alkanolamine form gets converted to the iminium form in the SDS micelle environment. The iminium form possesses positive charge and it seems that electrostatic interaction between the positively charged iminium and negatively charged surfactant leads to the stabilization of the iminium form in the Stern layer of the anionic micelle. Whereas the conversion of the alkanolamine form into the iminium form takes place and that can be monitored in naked eye since the iminium form is orange in colour and the alkanolamine form has blue violet emission. Such a detail insight about the photophysical properties of the benzophenanthridine alkaloids would be a valuable addition in the field of alkaloid-surfactant interaction.
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      PubDate: 2016-07-19T14:19:17Z
       
  • Mid infrared emission spectroscopy of carbon plasma
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Laszlo Nemes, Ei Ei Brown, Clayton S.-C. Yang, Uwe Hommerich
      Mid infrared time-resolved emission spectra were recorded from laser-induced carbon plasma. These spectra constitute the first study of carbon materials LIB spectroscopy in the mid infrared range. The carbon plasma was induced using a Q-switched Nd: YAG laser. The laser beam was focused to high purity graphite pellets mounted on a translation stage. Mid infrared emission from the plasma in an atmospheric pressure background gas was detected by a cooled HgCdTe detector in the range 4.4–11.6μm, using long-pass filters. LIB spectra were taken in argon, helium and also in air. Despite a gate delay of 10μs was used there were strong backgrounds in the spectra. Superimposed on this background broad and noisy emission bands were observed, the form and position of which depended somewhat on the ambient gas. The spectra were digitally smoothed and background corrected. In argon, for instance, strong bands were observed around 4.8, 6.0 and 7.5μm. Using atomic spectral data by NIST it could be concluded that carbon, argon, helium and nitrogen lines from neutral and ionized atoms are very weak in this spectral region. The width of the infrared bands supports molecular origin. The infrared emission bands were thus compared to vibrational features of carbon molecules (excluding C2) of various sizes on the basis of previous carbon cluster infrared absorption and emission spectroscopic analyses in the literature and quantum chemical calculations. Some general considerations are given about the present results.


      PubDate: 2016-07-19T14:19:17Z
       
  • Local viscosity and solvent relaxation experienced by rod-like
           fluorophores in AOT/4-chlorophenol/m-xylene organogels
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Manika Dandapat, Debabrata Mandal
      Organogels prepared from AOT/4-chlorophenol/m-xylene are immobile in the macroscopic sense, with a well-characterized internal structure. However, the molecular level dynamics inside the gels is not too clear, although a very slow structural relaxation has been reported previously. Using a set of rod-like fluorophores, we find that the rotational mobility of a small guest molecule inside the gel can be extremely fast, indicating presence of sufficiently low-microviscosity domains. These domains consist of m-xylene solvent molecules trapped in the interstices of fiber bundles comprising columnar stacks of 4-chlorophenol surrounded by AOT molecules. However, interstitial trapping of m-xylene does retard its own dynamics, which explains the slow solvent relaxation inside the gels. Hence, the state of m-xylene in the organogel may be characterized as “bound”, in contrast to the “free” state in neat m-xylene.
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      PubDate: 2016-07-19T14:19:17Z
       
  • Structural and optical studies on selected web spinning spider silks
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): R. Karthikeyani, A. Divya, T. Mathavan, R. Mohamed Asath, A. Milton Franklin Benial, K. Muthuchelian
      This study investigates the structural and optical properties in the cribellate silk of the sheet web spider Stegodyphus sarasinorum Karsch (Eresidae) and the combined dragline, viscid silk of the orb-web spiders Argiope pulchella Thorell (Araneidae) and Nephila pilipes Fabricius (Nephilidae). X-ray diffraction (XRD), Fourier transform infra-red (FTIR), Ultraviolet-visible (UV–Vis) and fluorescence spectroscopic techniques were used to study these three spider silk species. X-ray diffraction data are consistent with the amorphous polymer network which is arising from the interaction of larger side chain amino acid contributions due to the poly-glycine rich sequences known to be present in the proteins of cribellate silk. The same amorphous polymer networks have been determined from the combined dragline and viscid silk of orb-web spiders. From FTIR spectra the results demonstrate that, cribellate silk of Stegodyphus sarasinorum, combined dragline viscid silk of Argiope pulchella and Nephila pilipes spider silks are showing protein peaks in the amide I, II and III regions. Further they proved that the functional groups present in the protein moieties are attributed to α-helical and side chain amino acid contributions. The optical properties of the obtained spider silks such as extinction coefficients, refractive index, real and imaginary dielectric constants and optical conductance were studied extensively from UV–Vis analysis. The important fluorescent amino acid tyrosine is present in the protein folding was investigated by using fluorescence spectroscopy. This research would explore the protein moieties present in the spider silks which were found to be associated with α-helix and side chain amino acid contributions than with β-sheet secondary structure and also the optical relationship between the three different spider silks are investigated. Successful spectroscopic knowledge of the internal protein structure and optical properties of the spider silks could permit industrial production of silk-based fibres with unique properties under benign conditions.
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      PubDate: 2016-07-19T14:19:17Z
       
  • A multi writable thiophene-based selective and reversible chromogenic
           fluoride probe with dual –NH functionality
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Siddharth Vishwakarma, Ajit Kumar, Abha Pandey, K.K. Upadhyay
      A chromogenic fluoride probe bearing bis imine groups having dual –NH functionality (BSB) has been designed, synthesised and structurally characterized by its single crystal X-ray diffraction studies. The BSB could visually and spectroscopically recognise F− with high selectivity over other anions by exhibiting intense chromogenic response (from colourless to red) for F− in acetonitrile solution. The UV–visible titration and 1H NMR titration experiments indicated that the observed changes occur via a combined process including hydrogen bonding and deprotonation between the BSB and F−. Moreover theoretical calculations at the Density Functional Theory (DFT) level shed further light upon probe design strategy and the nature of interactions between BSB and F−. The limit of detection and binding constant of BSB towards F− were found to be 6.9×10−7 M and 1.42±0.069×108 M−2 respectively. Finally, by using F− and H+ as chemical inputs and the absorbance as output, a INHIBIT logic gate was constructed, which exhibits “Multi-write” ability without obvious degradation in its optical output.
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      PubDate: 2016-07-19T14:19:17Z
       
  • Design, properties and application of a facile fluorescence switch for
           Cu(II)
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Haipeng Diao, Weiping Niu, Wen Liu, Liheng Feng, Jun Xie
      A facile fluorescence switch based on Schiff base 2,2′-[1,3-phenylenbis- (methylidynenitrilo)]bis[benzenethiol] (PMBB) has been developed and used to sensing metal ions. UV–vis absorption and fluorescence emission spectra show that the PMBB receptor has high selectivity and sensitivity for Cu(II) ions. Based on the photoinduced electron transfer (PET) and chelation enhanced fluorescence (CHEF) mechanisms, the receptor exhibits an fluorescence “turn-on” switch signal for Cu(II). The 1:1 binding mode of PMBB and Cu (II) ions can be obtained by the Job-plot and ESI-Mass spectra data. Noticeably, the color changes (from colorless to yellow) of PMBB solutions for Cu(II) sensing can be observed by naked eyes in the sunlight. The detection limit of the receptor for Cu(II) may reach 10−7 mol/L with a good linear relation in the lower concentrations of Cu(II). To develop the practical application, the Cu(II) ions in swimming pool water samples were detected. Results show that PMBB receptor as a fluorescent probe can use to detect the trace level of Cu(II) in the environmental samples. This work contributes to providing a facile strategy for designing efficient probes and developing their practical application value.
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      PubDate: 2016-07-14T13:53:29Z
       
  • Flavonoid-surfactant interactions: A detailed physicochemical study
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Onkar Singh, Rajwinder Kaur, Rakesh Kumar Mahajan
      The aim of this article is to study the interactions between flavonoids and surfactants with attention of finding the probable location of flavonoids in micellar media that can be used for controlling their antioxidant behavior. In present study, the micellar and interfacial behavior of twin tailed anionic surfactants viz. sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and sodium bis(2-ethylhexyl)phosphate (NaDEHP) in the presence of two flavonoids, namely quercetin (QUE) and kaempferol (KFL) have been studied by surface tension measurements. UV–visible, fluorescence and differential pulse voltammetric (DPV) measurements have been employed to predict the probable location of flavonoids (QUE/KFL) within surfactant (AOT/NaDEHP) aggregates. Dynamic light scattering (DLS) measurements further confirmed the solubilization of QUE/KFL in AOT/NaDEHP aggregates deduced from increased hydrodynamic diameter (Dh) of aggregates in the presence of flavonoids. Both radical scavenging activity (RSA) and degradation rate constant (k) of flavonoids are found to be higher in NaDEHP micelles as compared to AOT micelles.
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      PubDate: 2016-07-14T13:53:29Z
       
  • Comprehensive near infrared study of Jatropha oil esterification with
           ethanol for biodiesel production
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Alianda Dantas de Oliveira, Ananda Franco de Sá, Maria Fernanda Pimentel, José Geraldo A. Pacheco, Claudete Fernandes Pereira, Maria Soledad Larrechi
      This work presents a comprehensive near infrared study for in-line monitoring of the esterification reaction of high acid oils, such as Jatropha curcas oil, using ethanol. Parallel reactions involved in the process were carried out to select a spectral region that characterizes the evolution of the esterification reaction. Using absorbance intensities at 5176cm−1, the conversion and kinetic behaviors of the esterification reaction were estimated. This method was applied to evaluate the influence of temperature and catalyst concentration on the estimates of initial reaction rate and ester conversion as responses to a 22 factorial experimental design. Employment of an alcohol/oil ratio of 16:1, catalyst concentration of 1.5% w/w, and temperatures at 65°C or 75°C, made it possible to reduce the initial acidity from 18% to 1.3% w/w, which is suitable for transesterification of high free fatty acid oils for biodiesel production. Using the proposed analytical method in the esterification reaction of raw materials with high free fatty acid content for biodiesel makes the monitoring process inexpensive, fast, simple, and practical.
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      PubDate: 2016-07-14T13:53:29Z
       
  • Design and synthesis of a new organic receptor and evaluation of
           colorimetric anion sensing ability in organo-aqueous medium
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): P. Srikala, Kartick Tarafder, Darshak R. Trivedi
      A new organic receptor has been designed and synthesized by the combination of aromatic dialdehyde with nitro-substituted aminophenol resulting in a Schiff base compound. The receptor exhibited a colorimetric response for F− and AcO− ion with a distinct color change from pale yellow to red and pink respectively in dry DMSO solvent and yellow to pale greenish yellow in DMSO:H2O (9:1, v/v). UV–Vis titration studies displayed a significant shift in absorption maxima in comparison with the free receptor. The shift could be attributed to the hydrogen bonding interactions between the active anions and the hydroxyl functionality aided by the electron withdrawing nitro substituent on the receptor. 1H NMR titration and density functionality studies have been performed to understand the nature of interaction of receptor and anions. The lower detection limit of 1.12ppm was obtained in organic media for F− ion confirming the real time application of the receptor.
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      PubDate: 2016-07-14T13:53:29Z
       
  • Facile room temperature deposition of gold nanoparticle-ionic liquid
           hybrid film on silica substrate
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): S. Krishnamurthy, D. Harikishore Kumar Reddy, G. Sankar, Yeoung-Sang Yun
      This work presents facile synthesis of gold nanoparticle (Au NP)-ionic liquid hybrid film of <10nm by a simple two-step process at room temperature by deposition of Au NPs suspended in 1-hexyl-1methyl-pyrolidinium bromide, on Si (111) substrates. FTIR results demonstrated that ionic liquid properties remain unaltered during and after Au NP synthesis, and even coating on Si (111) substrate. XRD, XPS, and XAS spectral data confirm the presence of Au(0) while EXAFS data indicated the presence of small particles or incomplete surface species. Cross-sectional analysis using FE-SEM and edge length measurement using AFM showed that the film thickness is ca 10nm.
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      PubDate: 2016-07-14T13:53:29Z
       
  • Overall uncertainty measurement for near infrared analysis of
           cryptotanshinone in tanshinone extract
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Zhong Xue, Bing Xu, Xinyuan Shi, Chan Yang, Xianglong Cui, Gan Luo, Yanjiang Qiao
      This study presented a new strategy of overall uncertainty measurement for near infrared (NIR) quantitative analysis of cryptotanshinone in tanshinone extract powders. The overall uncertainty of NIR analysis from validation data of precision, trueness and robustness study was fully investigated and discussed. Quality by design (QbD) elements, such as risk assessment and design of experiment (DOE) were utilized to organize the validation data. An “I × J × K” (series I, the number of repetitions J and level of concentrations K) full factorial design was used to calculate uncertainty from the precision and trueness data. And a 27–4 Plackett–Burmann matrix with four different influence factors resulted from the failure mode and effect analysis (FMEA) analysis was adapted for the robustness study. The overall uncertainty profile was introduced as a graphical decision making tool to evaluate the validity of NIR method over the predefined concentration range. In comparison with the T. Saffaj's method (Analyst, 2013, 138, 4677.) for overall uncertainty assessment, the proposed approach gave almost the same results, demonstrating that the proposed method was reasonable and valid. Moreover, the proposed method can help identify critical factors that influence the NIR prediction performance, which could be used for further optimization of the NIR analytical procedures in routine use.
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      PubDate: 2016-07-14T13:53:29Z
       
  • Experimental and theoretical investigation of the complexation of
           methacrylic acid and diisopropyl urea
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Peter Pogány, Mayamin Razali, Gyorgy Szekely
      The present paper explores the complexation ability of methacrylic acid which is one of the most abundant functional monomer for the preparation of molecularly imprinted polymers. Host-guest interactions and the mechanism of complex formation between methacrylic acid and potentially genotoxic 1,3-diisopropylurea were investigated in the pre-polymerization solution featuring both experimental (NMR, IR) and in silico density functional theory (DFT) tools. The continuous variation method revealed the presence of higher-order complexes and the appearance of self-association which were both taken into account during the determination of the association constants. The quantum chemical calculations – performed at B3LYP 6-311++G(d,p) level with basis set superposition error (BSSE) corrections – are in agreement with the experimental observations, reaffirming the association constants and justifying the validity of computational investigation of such systems. Furthermore, natural bond orbital analysis was carried out to appraise the binding properties of the complexes.
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      PubDate: 2016-07-14T13:53:29Z
       
  • Infrared and Raman spectroscopic characterizations on new Fe
           sulphoarsenate hilarionite (Fe2(III)(SO4)(AsO4)(OH)·6H2O):
           
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Jing Liu, LiLe He, Faqin Dong, Ray L. Frost
      Hilarionite (Fe2 (SO4)(AsO4)(OH)·6H2O) is a new Fe sulphoarsenates mineral, which recently is found in the famous Lavrion ore district, Atliki Prefecture, Greece. The spectroscopic study of hilarionite enriches the data of arsenic mineralogy in supergene environment of a mine area. The infrared and Raman means are used to characterize the molecular structure of this mineral. The IR bands at 875 and 905cm−1 are assigned to the antisymmetric stretching vibrations of AsO4 3−. The IR bands at 1021, 1086 and 1136cm−1 correspond to the possible antisymmetric and symmetric stretching vibrations of SO4 2−. The Raman bands at 807, 843 and 875cm−1 clearly show that arsenate components in the mineral structure, which are assigned to the symmetric stretching vibrations (ν1) of AsO4 3− (807 and 843cm−1) and the antisymmetric vibration (ν3) (875cm−1). IR bands provide more sulfate information than Raman, which can be used as the basis to distinguish hilarionite from kaňkite. The powder XRD data shows that hilarionite has obvious differences with the mineral structure of kaňkite. The thermoanalysis and SEM-EDX results show that hilarionite has more sulfate than arsenate.
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      PubDate: 2016-07-09T00:52:27Z
       
  • Applying graphene oxide nano-film over a polycarbonate nanoporous membrane
           to monitor E. coli by infrared spectroscopy
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Krishna Pal Singh, Neeraj Singh Dhek, Anuj Nehra, Sweeti Ahlawat, Anu Puri
      Nano-biosensors are excellent monitoring tools for rapid, specific, sensitive, inexpensive, in-field, on-line, and/or real-time detection of pathogens in foods, soil, air, and water samples. A variety of nano-materials (metallic, polymeric, and/or carbon-based) were employed to enhance the efficacy, efficiency, and sensitivity of these nano-biosensors, including graphene-based materials, especially graphene oxide (GO)-based materials. GO bears many oxygen-bearing groups, enabling ligand conjugation at the high density critical for sensitive detection. We have fabricated GO-modified nano-porous polycarbonate track-etched (PCTE) membranes that were conjugated to an Escherichia coli-specific antibody (Ab) and used to detect E. coli. The random distribution of nanopores on the PCTE membrane surface and the bright coating of the GO onto the membrane were confirmed by scanning electron microscope. Anti-E. coli β-gal Abs were conjugated to the GO surface via 1-ethyl-3,3-dimethylaminopropyl carbodiimide hydrochloride–N-hydroxysuccinimide chemistry; antibody coating was confirmed by the presence of a characteristic IR peak near 1600cm−1. A non-corresponding Ab (anti-Pseudomonas) was used as a negative control under identical conditions. When E. coli interacted anti-E.coli β-gal with Ab-coated GO-nano-biosensor units, we observed a clear shift in the IR peak from 3373.14 to 3315cm−1; in contrast, we did not observe any shift in IR peaks when the GO unit was coated with the non-corresponding Ab (anti-Pseudomonas). Therefore, the detection of E. coli using the described GO-nano-sensor unit is highly specific, is highly selective and can be applied for real-time monitoring of E. coli with a detection limit between 100μg/mL and 10μg/mL, similar to existing detection systems.
      Graphical abstract image

      PubDate: 2016-07-09T00:52:27Z
       
  • Fourier transform infrared spectroscopy and chemometrics for the
           characterization and discrimination of writing/photocopier paper types:
           Application in forensic document examinations
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Raj Kumar, Vinay Kumar, Vishal Sharma
      The aim of the present work is to explore the non-destructive application of ATR-FTIR technique for characterization and discrimination of paper samples which could be helpful to give forensic aid in resolving legal cases. Twenty-four types of paper brands were purchased from local market in and around Chandigarh, India. All the paper samples were subjected to ATR-FTIR analysis from 400 to 4000cm−1 wavenumber range. The qualitative feature and Chemometrics of the obtained spectral data are used for characterization and discrimination. Characterization is achieved by matching the peaks with standards of cellulose and inorganic fillers, a usual constituents of paper. Three different regions of IR, i.e. 400–2000cm−1, 2000–4000cm−1 and 400–4000cm−1 were selected for differentiation by Chemometrics analysis. The discrimination is achieved on the basis of three principal components, i.e. PC 1, PC 2 and PC 3. It is observed that maximum discrimination was procured in the wave number range of i.e. 2000–4000cm−1. Discriminating power was calculated on the basis of qualitative features as well, and it is found that the discrimination of paper samples was better achieved by Chemometrics analysis rather than qualitative features. The discriminating power by Chemometrics is 99.64% and which is larger as ever achieved by any group for present number of samples. The present result confirms that this study will be highly useful in forensic document examination work in the legal cases, where the authenticity of the document is challenged. The results are completely analytical and, therefore, overcome the problem encounter in traditional routine light/radiation scanning methods which are still in practice by various questioned document laboratories.
      Graphical abstract image

      PubDate: 2016-07-09T00:52:27Z
       
  • Raman microspectroscopy of Hematoporphyrins. Imaging of the noncancerous
           and the cancerous human breast tissues with photosensitizers
    • Abstract: Publication date: 5 December 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 169
      Author(s): B. Brozek-Pluska, M. Kopec
      Raman microspectroscopy combined with fluorescence were used to study the distribution of Hematoporphyrin (Hp) in noncancerous and cancerous breast tissues. The results demonstrate the ability of Raman spectroscopy to distinguish between noncancerous and cancerous human breast tissue and to identify differences in the distribution and photodegradation of Hematoporphyrin, which is a photosensitizer in photodynamic therapy (PDT), photodynamic diagnosis (PDD) and photoimmunotherapy (PIT) of cancer. Presented results show that Hematoporphyrin level in the noncancerous breast tissue is lower compared to the cancerous one. We have proved also that the Raman intensity of lipids and proteins doesn't change dramatically after laser light irradiation, which indicates that the PDT treatment destroys preferably cancer cells, in which the photosensitizer is accumulated. The specific subcellular localization of photosensitizer for breast tissues samples soaked with Hematoporphyrin was not observed.
      Graphical abstract image

      PubDate: 2016-07-04T04:18:57Z
       
  • Spectroscopic study of 3-Hydroxyflavone - protein interaction in lipidic
           bi-layers immobilized on silver nanoparticles
    • Abstract: Publication date: 5 January 2017
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 170
      Author(s): Mariana Voicescu, Sorana Ionescu, Cristina L. Nistor
      The interaction of 3-Hydroxyflavone with serum proteins (BSA and HSA) in lecithin lipidic bi-layers (PC) immobilized on silver nanoparticles (SNPs), was studied by fluorescence and Raman spectroscopy. BSA secondary structure was quantified with a deconvolution algorithm, showing a decrease in α-helix structure when lipids were added to the solution. The effect of temperature on the rate of the excited-state intra-molecular proton transfer and on the dual fluorescence emission of 3-HF in the HSA/PC/SNPs systems was discussed. Evaluation of the antioxidant activity of 3-HF in HSA/PC/SNPs systems was also studied. The antioxidant activity of 3-HF decreased in the presence of SNPs. The results are discussed with relevance to the secondary structure of proteins and of the 3-HF based nano-systems to a topical formulation useful in the oxidative stress process.
      Graphical abstract image

      PubDate: 2016-07-04T04:18:57Z
       
  • Photophysical performance comparison between bulk Cu(I) complex and its
           electrospinning fibers: Synthesis and characterization
    • Abstract: Publication date: 5 December 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 169
      Author(s): Wan Pu, Zhao Yuqing, Wang Lisha
      In this report, a diamine ligand having an electron-pulling group in its conjugation plane was designed. A methyl group was connected with this diamine ligand, hoping to further increase its steric hindrance. Its Cu(I) complex was synthesized and characterized by NMR, single crystal analysis and photophysical analysis. There was a distorted tetrahedral coordination field in this Cu(I) complex. Its onset electronic transition owned a mixed character of metal-to-ligand-charge-transfer which suffered from bad geometric relaxation. To limit this geometric relaxation and improve emissive performance, this Cu(I) complex was doped into a polymer host through electrospinning technique. Photophysical comparison between solid state sample, solution sample and composite samples indicated that excited state geometric relaxation was effectively limited by polymer immobilization effect, resulting in improved emissive performance, such as emission blue shift, long emission decay lifetime and better photostability.
      Graphical abstract image

      PubDate: 2016-06-18T21:51:29Z
       
  • A colorimetric and fluorescence enhancement anion probe based on coumarin
           compounds
    • Abstract: Publication date: 5 December 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 169
      Author(s): Limin Zhao, Ge Liu, Baofeng Zhang
      In this paper, anion probe 1 was designed and synthesized by using phenprocoumon containing acyl hydrazine with p-nitro azo salicylaldehyde reaction Dickson et al. (2008) Dickson et al. (2008) [1] . In the anion probe 1, the nitro moiety is a signaling group and the phenolic hydroxyl moiety is anion binding site. Then the anion probe 1 was characterized by mass spectra (MS) and infrared spectra (IR). The binding properties of the anion probe 1 for anions such as F−, AcO−, H2PO4 −, OH−, Cl−, Br− and I− were investigated by ultraviolet-visible (UV–Vis) spectra and fluorescence spectra Shao et al. (2008) Shao et al. (2008) [2] . Furthermore, the color of anion probe 1 after addition of F−, AcO−, H2PO4 − and OH− in DMSO changed from yellow to blue, while no obvious color changes were observed by addition of other tested anions. Accordingly, the anion probe 1 could sense visually F−, AcO−, H2PO4 − and OH− without resorting to any spectroscopic instrumentation Amendola et al. (2010) Amendola et al. (2010) [3] .
      Graphical abstract image

      PubDate: 2016-06-18T21:51:29Z
       
  • A fluorescence turn-on chemosensor for hydrogen sulfate anion based on
           quinoline and naphthalimide
    • Abstract: Publication date: 5 December 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 169
      Author(s): Zaoli Luo, Kai Yin, Zhu Yu, Mengxue Chen, Yan Li, Jun Ren
      A new fluorescence turn-on chemosensor 1 based on quinoline and naphthalimide was prepared and its anion sensing toward various anions behavior was explored in this paper. Sensor 1 exhibited a highly selective fluorescent response toward HSO4 − with an 8-fold fluorescence intensity enhancement in the presence of 10equiv. of HSO4 − in DMSO-H2O (1/1, v/v) solution. The sensor also displayed high sensitivity to hydrogen sulfate and the detection limit was calculated to be 7.79×10−7 M. The sensing mechanism has been suggested to proceed via a hydrolysis process of the Schiff base group. The hydrolysis product has been isolated and further identified by 1H NMR and MS.
      Graphical abstract image

      PubDate: 2016-06-18T21:51:29Z
       
  • Full spectrum and selected spectrum based multivariate calibration methods
           for simultaneous determination of betamethasone dipropionate, clotrimazole
           and benzyl alcohol: Development, validation and application on commercial
           dosage form
    • Abstract: Publication date: 5 December 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 169
      Author(s): Hany W. Darwish, Eman S. Elzanfaly, Ahmed S. Saad, Abdelaziz El-Bayoumi Abdelaleem
      Five different chemometric methods were developed for the simultaneous determination of betamethasone dipropionate (BMD), clotrimazole (CT) and benzyl alcohol (BA) in their combined dosage form (Lotriderm® cream). The applied methods included three full spectrum based chemometric techniques; namely principal component regression (PCR), Partial Least Squares (PLS) and Artificial Neural Networks (ANN), while the other two methods were PLS and ANN preceded by genetic algorithm procedure (GA-PLS and GA-ANN) as a wavelength selection procedure. A multilevel multifactor experimental design was adopted for proper construction of the models. A validation set composed of 12 mixtures containing different ratios of the three analytes was used to evaluate the predictive power of the suggested models. All the proposed methods except ANN, were successfully applied for the analysis of their pharmaceutical formulation (Lotriderm® cream). Results demonstrated the efficiency of the four methods as quantitative tool for analysis of the three analytes without prior separation procedures and without any interference from the co-formulated excipient. Additionally, the work highlighted the effect of GA on increasing the predictive power of PLS and ANN models.
      Graphical abstract image

      PubDate: 2016-06-18T21:51:29Z
       
  • Fluorescence characteristics of carbon nanoemitters derived from sucrose
           by green hydrothermal and microwave methods
    • Abstract: Publication date: 5 December 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 169
      Author(s): Rajesh Patidar, Babulal Rebary, Gopala Ram Bhadu
      In this work, fluorescent carbon nanoparticles (CNPs) were prepared through two green methods i.e. microwave and hydrothermal, using sucrose as carbon precursor. Both of these methods have offered fluorescent CNPs as characterized by TEM, FTIR, zeta potential, absorbance and emission techniques. Excitation dependent emission spectra were exhibited by aqueous dispersion of these CNPs when they were subjected to different excitation wavelengths. The luminous characteristics of CNPs obtained from both of these methods were studied and compared. Their fluorescence stability in water and buffer was monitored for about three months. Influence of pH and various metal ions on emission spectra were investigated.
      Graphical abstract image

      PubDate: 2016-06-15T17:06:42Z
       
  • Room temperature fluorescence and phosphorescence study on the
           interactions of iodide ions with single tryptophan containing serum
           albumins
    • Abstract: Publication date: 5 December 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 169
      Author(s): Krystian Gałęcki, Agnieszka Kowalska-Baron
      In this study, the influence of heavy-atom perturbation, induced by the addition of iodide ions, on the fluorescence and phosphorescence decay parameters of some single tryptophan containing serum albumins isolated from: human (HSA), equine (ESA) and leporine (LSA) has been studied. The obtained results indicated that, there exist two distinct conformations of the proteins with different exposure to the quencher. In addition, the Stern–Volmer plots indicated saturation of iodide ions in the binding region. Therefore, to determine quenching parameter, we proposed alternative quenching model and we have performed a global analysis of each conformer to define the effect of iodide ions in the cavity by determining the value of the association constant. The possible quenching mechanism may be based on long-range through-space interactions between the buried chromophore and quencher in the aqueous phase. The discrepancies of the decay parameters between the albumins studied may be related with the accumulation of positive charge at the main and the back entrance to the Drug Site 1 where tryptophan residue is located.
      Graphical abstract image

      PubDate: 2016-06-15T17:06:42Z
       
  • Raman scattering or fluorescence emission? Raman spectroscopy study on
           lime-based building and conservation materials
    • Abstract: Publication date: 5 December 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 169
      Author(s): Zofia Kaszowska, Kamilla Malek, Emilia Staniszewska-Slezak, Karina Niedzielska
      This work presents an in-depth study on Raman spectra excited with 1064 and 532nm lasers of lime binders employed in the past as building materials and revealed today as valuable conservation materials. We focus our interest on the bands of strong intensity, which are present in the spectra of all binders acquired with laser excitation at 1064nm, but absent in the corresponding spectra acquired with laser excitation at 532nm. We suggest, that the first group of spectra represents fluorescence phenomena of unknown origin and the second true Raman scattering. In our studies, we also include two other phases of lime cycle, i.e. calcium carbonate (a few samples of calcite of various origins) and calcium oxide (quicklime) to assess how structural and chemical transformations of lime phases affect the NIR-Raman spectral profile. Furthermore, we analyse a set of carbonated limewashes and lime binders derived from old plasters to give an insight into their spectral characteristics after excitation with the 1064nm laser line. NIR-Raman micro-mapping results are also presented to reveal the spatial distribution of building materials and fluorescent species in the cross-section of plaster samples taken from a 15th century chapel. Our study shows that the Raman analysis can help identify lime-based building and conservation materials, however, a caution is advised in the interpretation of the spectra acquired using 1064nm excitation.
      Graphical abstract image

      PubDate: 2016-06-15T17:06:42Z
       
  • Water-soluble Hantzsch ester as switch-on fluorescent probe for
           efficiently detecting nitric oxide
    • Abstract: Publication date: 5 December 2016
      Source:Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, Volume 169
      Author(s): Hui-Li Wang, Fu-Tao Liu, Ai-Xiang Ding, Su-Fang Ma, Lan He, Lan Lin, Zhong-Lin Lu
      A water soluble Hantzsch ester derivative of coumarin, DHPS, was synthesized and successfully applied in the fluorescent sensing nitric oxide (NO) in aqueous solution. The fluorescence of probe DHPS is extremely weak, while its fluorescence was greatly switched on upon the addition of NO solution and showed high selectivity and sensitivity to NO. The limitation of the detection was calculated to be 18nM. The NO-induced aromatization of dihydropyridine in DHPS to pyridine derivative (PYS) proved to be the switching mechanism for the fluorescent sensing process, which was confirmed through spectra characterization and computation study. Cytotoxicity assay demonstrated both DHPS and PYS are biocompatible, the DHPS was successfully applied to track the endogenously produced NO in the RAW 264.7 cells.
      Graphical abstract image

      PubDate: 2016-06-15T17:06:42Z
       
 
 
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