Fluorescence Spectral Analysis Research Articles

Inhibitory effects of a sulfated polysaccharide isolated from edible red alga Bangia fusco-purpurea on α-amylase and α-glucosidase.

In this study, a sulfated polysaccharide (BFP) was isolated from the edible red alga Bangia fusco-purpurea. Gel-filtration and thin layer chromatographically analyses suggested that BFP was a homogenous polysaccharide. The chemical structural analysis revealed that BFP mainly consisted of galactose together with a small amount of uronic acid, mannose, and glucose. Its molecular mass was estimated to be 133.18 kDa by high-performance liquid chromatography (HPLC) analysis. BFP inhibited α-amylase and α-glucosidase in a concentration-dependent manner. The IC50 values of BFP against α-amylase and α-glucosidase were estimated to be 1.26 ± 0.11 mg/mL and 1.34 ± 0.07 mg/mL, respectively. Kinetic analyses suggested that BFP showed competitive and non-competitive inhibition against α-amylase and α-glucosidase, respectively. Circular dichroism spectral and fluorescence spectral analyses suggested that BFP affects the conformational structures of these enzymes, which may lead to the inhibition of the enzymatic activities. Abbreviations: Ara: D-arabinose; AnGal: anhydro-L-galactose residues; CD spectroscopy: Circular Dichroism spectroscopy; DNS: dinitrosalicylic acid; FT-IR: fourier transform infrared spectra; Fuc: L-fucose; Gal: D-galactose; Glc: D-glucose; GlcA: D-Glucuronic acid; HPLC: high performance liquid chromatography; Man: D-mannose; pNPG: p-nitrophenyl-α-D-glucoside; TFA: trifluoroacetic acid; TLC: thin-layer chromatography; PMP: 1-phenyl-3-methyl-5-pyrazolone; Xyl: D-xylose.

Development of Nickel Doped Zinc Ferrite Nanocomposites as Magnetically Recoverable Catalytic Material for The Synthesis of Biphenyl Methane

Magnetically active nickel doped zinc ferrite nanoparticles with chemical composition NixZn1-xFe2O4 (x- 0.0, 0.25, 0.5, 0.75 and 1.0) were successfully synthesized by sol-gel auto-combustion method using high purity metal nitrates and ethylene glycol as gelling agent. The prepared samples were characterized by X-ray Diffraction (XRD), Transmission Electron Microscopy (TEM), X-ray Fluorescence (XRF) and Fourier Transform Infra-Red spectral (FTIR) analyses. TEM images and particle size distribution profile reveals the agglomeration tendency during nickel doping suggest the magnetic nature of particles. The remarkable change in the magnetic behaviour of nickel doped zinc ferrite samples provide an easy recovery and regeneration of the material and thus making an excellent candidate for benzylation reaction without any remarkable fall in the catalytic performance for repeated cycles.

Diversity evolution of functional bacteria and resistance genes (CzcA) in aerobic activated sludge under Cd(II) stress

An activated sludge sequencing batch reactor (SBR) was used to treat divalent cadmium (Cd(II)) wastewater for 60 d to investigate the overall treatment performance, evolution of the bacterial community, and abundance of the Cd(II) resistance gene CzcA and shifts in its potential host bacteria. During stable operation with a Cd(II) concentration of 20 mg/L, the average removal efficiencies of Cd(II) and chemical oxygen demand (COD) were more than 85% and that of total phosphorus was greater than 70%, while the total nitrogen (TN) was only about 45%. The protein (PN) content in the extracellular polymeric substances (EPS) increased significantly after Cd(II) addition, while polysaccharides displayed a decreasing trend (p < 0.05), indicating that EPS prefer to release PN to adsorb Cd(II) and protect bacteria from damage. Three-dimensional fluorescence spectral analysis showed that fulvic acid-like substances were the most abundant chemical components of EPS. The addition of Cd(II) adversely affected most denitrifying bacteria (p < 0.05), which is consistent with the low TN removal. In addition, quantitative polymerase chain reaction analysis revealed that CzcA gene abundance decreased as the Cd(II) concentration increased, possibly because expression of the CzcA gene was inhibited by Cd(II) stress. The majority of CzcA gene sequences were carried by Pseudomonas, making it the dominant genus among Cd(II)-resistant bacteria.

Design of Dyson Flow Cytometry System

In order to meet the needs of the flow cytometry for the simultaneous analysis of multiple fluorescence wavelengths and small volume, the design method of flow cytometry spectrum analysis system is presented by analyzing the characteristics of Dyson structure. And according to the method, a flow cytometry spectrum analysis system is disigned with Dyson type.The system's spectral range is 400 nm to 800 nm, the defocused spot size is less than the pixel size 24μ mm, the ransfer function value is above 0.8 at the Nyquist cut-off frequency 21 lp/mm,the spectral resolution is less than 3 nm, and the overall size is 83.54 mm×85.60 mm.The system has good optical performance and small volume, which meets the needs of the flow cytometry fluorescence spectral analysis. The outstanding innovation of this system is the application of Dyson light splitting structure and EMCCD detector which is high speed and high sensitivity.

Fluorescence spectral shape analysis for nucleotide identification

We report a conjugated polyelectrolyte fluorescence-based biosensor P-C-3 and a general methodology to evaluate spectral shape recognition to identify biomolecules using artificial intelligence. By using well-defined analytes, we demonstrate that the fluorescence spectral shape of P-C-3 is sensitive to minor structural changes and exhibits distinct signature patterns for different analytes. A method was also developed to select useful features to reduce computational complexity and prevent overfitting of the data. It was found that the normalized intensity of 3 to 5 selected wavelengths was sufficient for the fluorescence biosensor to classify 13 distinct nucleotides and distinguish as little as single base substitutions at distinct positions in the primary sequence of oligonucleotides rapidly with nearly 100% classification accuracy. Photophysical studies led to a model to explain the mechanism of these fluorescence spectral shape changes, which provides theoretical support for applying this method in complicated biological systems. Using the feature selection algorithm to measure the relative intensity of a few selected wavelengths significantly reduces measurement time, demonstrating the potential for fluorescence spectrum shape analysis in high-throughput and high-content screening.

Optical Properties of Azo-Benzothiazole Side Chain Liquid Crystalline Polymers: Effect of Solvents, Substituents and Temperatures.

The optical properties of a series of side chain liquid crystalline polymers (P1-P3) containing azo-benzothiazole mesogen with different terminal substituents (-H, -CH3 and -OCH2CH3) in four organic solvents of varying polarity have been investigated by absorption and fluorescence spectral analysis. Solvatochromic studies of P1-P3 did not show any regular variation on the absorption and emission intensities with changing the polarity of solvent. Theoretical studies were performed based on different solvent correlation methods such as Dimroth-Reichardt and Kamlet-Taft methods to investigate the solute-solvent interactions. Both absorption and emission maxima of investigated polymers were bathochromically shifted with the replacement of sixth position hydrogen atom by electron donating groups in benzothiazole moiety. The emission intensities of the studied polymers showed decreasing trend with increasing temperature.

Synthesis and photo-induced stereomutation of helical, π-stacked copolymers of dibenzofulvene and menthyl methacrylate

Copolymerization of dibenzofulvene (DBF) with (−)-menthyl methacrylate ((1R,2S,5R)-5-methyl-2-(1-methylethyl)cyclohexyl methacrylate) (MnMA) prepared from L-(-)-menthol ((1R,2S,5R)-(-)-5-methyl-2-(1-methylethyl)cyclohexanol) and methacrylic chloride was conducted under free radical conditions in toluene using α,α′-azobisisobutylonitrile (AIBN). DBF exhibited much higher reactivity compared with MnMA under all conditions examined in this work, leading to the products comprised mainly of DBF units. NMR, UV, and fluorescence spectral analyses indicated that higher-molar-mass copolymers have completely π-stacked DBF sequences with high conformational regularity while lower-molar-mass copolymers possess both π-stacked and unstacked DBF units in the chain. The ratios of π-stacked and unstacked side-chain fluorene groups of DBF units in excited states were determined by fluorescent emission spectra. The chiral copolymers exhibited circular dichroism (CD) spectra in the wavelength range of absorbance of side-chain fluorene units, suggesting that a preferred left-handed helical conformation was induced by the chirality of MnMA units. In addition, a conformational transformation leading to a loss of optical activity was induced by photo irradiation while the chirality of the copolymers was stable in tetrahydrofuran solution on heating up to 60 °C. The stereomutation was suggested to be a helix-to-random transition.

Quantifying length-dependent DNA end-binding by nucleoproteins

The ends of nucleic acids oligomers alter the statistics of interior nonspecific ligand binding and act as binding sites with altered properties. While the former aspect of “end effects” has received much theoretical attention in the literature, the physical nature of end-binding, and hence its potential impact on a wide range of studies with oligomers, remains poorly known. Here, we report for the first time end-binding to DNA using a model helix-turn-helix motif, the DNA-binding domain of ETV6, as a function of DNA sequence length. Spectral analysis of ETV6 intrinsic tryptophan fluorescence by singular value decomposition showed that end-binding to nonspecific fragments was negligible at >0.2 kbp and accumulated to 8% of total binding to 23-bp oligomers. The affinity for end-binding was insensitive to salt but tracked the affinity of interior binding, suggesting translocation from interior sites rather than free solution as its mechanism. As the presence of a cognate site in the 23-bp oligomer suppressed end-binding, neglect of end-binding to the short cognate DNA does not introduce significant error. However, the same applies to nonspecific DNA only if longer fragments (>0.2 kbp) are used.

A new spray deposition pattern measurement system based on spectral analysis of a fluorescent tracer

To complement shortages of discrete sampling data and improve the detection accuracy of droplet deposition in unmanned aerial vehicle (UAV) spraying, we developed a new spray deposition pattern measurement system (SDPMS) based on a fluorescent tracer and spectral analysis. Then, we evaluated the system performance in two field spraying experiments in comparison with water-sensitive paper results. The system comprises a fluorescence scanner and spectral analysis program. The fluorescence scanner includes an ultraviolet light, spectrometer, far end controller, stepping motor, and sample reel. First, 1.0% fluorescent tracer solution is sprayed, and the droplets are collected on a paper strip. Then, the paper strip is scanned with the fluorescence scanner, and a set of fluorescence intensity values is collected and processed by the spectral analysis program. Finally, the spray deposition pattern is calculated. The experimental results showed that the spray deposition pattern from the SDPMS had a 0.89 correlation coefficient with that of water-sensitive paper. A linear regression model between fluorescence intensity and deposit coverage was constructed, with a coefficient of determination of 0.91 (F = 61.8845, P < 0.001). In addition, a linear regression model between fluorescence intensity and volume rate was constructed, with a coefficient of determination of 0.89 (F = 51.6639, P < 0.001). The SDPMS and field experiments offer a good foundation for the development of an improved system compatible with UAV spraying.

Effect of tyrosinase‐catalyzed crosslinking on the structure and allergenicity of turbot parvalbumin mediated by caffeic acid

Enzymatic treatment of allergenic protein can alter their functional properties under a mild reaction condition due to specificity of enzymes. Phenolic compounds act as mediators and enhance the crosslinking reactions. The study aimed to assess the changes in the structure and immunoglobulin G (IgG) binding capacity of turbot parvalbumin (PV) upon crosslinking with tyrosinase (Tyr) in the absence and presence of caffeic acid. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis revealed the appearance of higher molecular weight bands (24, 36 kDa) in the crosslinked PV. The secondary structure of crosslinked PV became loosened and disordered. The results of intrinsic fluorescence and ultraviolet absorption spectral analyses, as well as surface hydrophobicity and free amino group analyses also revealed structural changes. As observed by western blot analysis, the intensity of the PV bands reduced upon Tyr treatment, indicating reduced binding of specific IgG to PV. Moreover, the indirect ELISA (enzyme-linked immunosorbent assay) analysis confirmed that the IgG binding ability of crosslinked PV was reduced 34.94%. Enzymatic treatment mitigated the allergenicity of fish PV, which was closely related to the alterations in the conformational structure. This treatment showed potential for developing hypoallergenic fish products under mild reaction conditions. © 2019 Society of Chemical Industry.

A New Samarium(III) Complex of Liriodenine: Synthesis, Crystal Structure, Antitumor Activity, and DNA Binding Study

A novel SmIII complex [SmIII(LA)2(pic)3] (Hpic = picric acid), in which LA is a natural‐derived alkaloid, liriodenine, was synthesized and characterized by IR, elemental analysis, and single‐crystal X‐ray diffraction analysis. This complex showed enhanced solubility compared with liriodenine and its metal complexes that have been previously reported. The interaction of the SmIII complex with ct‐DNA was further investigated by various spectroscopic techniques, such as UV/Vis spectroscopy, fluorescence spectroscopy, circular dichroism spectroscopy (CD), and viscosity measurement. The results showed that the intrinsic binding constant Kb of the SmIII complex with ct‐DNA was calculated to be 5.03 × 103 L·mol–1 by UV/Vis absorption spectral analysis. The thermodynamic fluorescent spectral analysis suggested that the fluorescence intensity of the SmIII complex was weakened by ct‐DNA mainly through a dynamic quenching mechanism. The presence of Sm complex could increase the viscosity of DNA solution, so it was concluded that the complex bound with ct‐DNA via a moderate intercalative mode. Furthermore, this SmIII complex exhibited significant growth inhibition on the three typical tumor cell lines, HepG2, T‐24, and SK‐OV‐3, with the corresponding IC50 values, 10.76 ± 0.19, 8.85 ± 1.12, and 10.01 ± 0.55 μM, respectively. The in vitro antitumor activity was comparable with LA and cisplatin, which suggested that it might be a new broad spectrum antitumor agent with more satisfying solubility.

Design, synthesis and biological evaluation of novel inhibitors against cyanobacterial pyruvate dehydrogenase multienzyme complex E1.

Cyanobacterial pyruvate dehydrogenase multienzyme complex E1 (PDHc E1) is a potential target enzyme for finding inhibitors to control harmful cyanobacterial blooms. In this study, a series of novel triazole thiamin diphosphate (ThDP) analogs were designed and synthesized by modifying the substituent group of triazole ring and optimizing triazole-benzene linker as potential cyanobacterial PDHc E1 (Cy-PDHc E1) inhibitors. Their inhibitory activities against Cy-PDHc E1 in vitro and algicide activities in vivo were further examined. Most of these compounds exhibited prominent inhibitory activities against Cy-PDHc E1 (IC50 1.48-4.48 μM) and good algicide activities against Synechocystis PCC6803 (EC50 0.84-2.44 µM) and Microcystis aeruginosa FACHB905 (EC50 0.74-1.77 µM). Especially, compound 8d showed not only the highest inhibitory activity against Cy-PDHc E1 (IC50 1.48 μM), but also the most powerful inhibitory selectivity between Cy-PDHc E1 (inhibitory rate 98.90%) and porcine PDHc E1 (inhibitory rate only 9.54%). Furthermore, the potential interaction between compound 8d and Cy-PDHc E1 was analyzed by a molecular docking method and site-directed mutagenesis and enzymatic analysis and fluorescence spectral analysis. These results indicated that compound 8d could be used as a hit compound for further optimization and might have potential to be developed as a new algicide.

Using the method of principal components in study of the data obtained by means of X-ray fluorescent spectral analysis on the elemental composition of clothing damages areas at the shooting of nonlethal elastic bullets "Teren-12P" ammunition

Using the method of principal components in study of the data obtained by means of X-ray fluorescent spectral analysis on the elemental composition of clothing damages areas at the shooting of nonlethal elastic bullets "Teren-12P" ammunition

Rhodium-catalyzed C-H activation/annulation of amidines with 4-diazoisochroman-3-imines toward isochromeno[3,4-c]isoquinolines.

A rhodium-catalyzed C-H activation/annulation of amidines with 4-diazoisochroman-3-imines has been established to afford a series of 8-amino-5H-isochromeno[3,4-c]isoquinolines in moderate to good yields with good functional group tolerance. This reaction proceeded in a sequential C-H activation/carbene migration insertion/intramolecular annulation procedure and featured the construction of a C-C and C-N bond in one pot. UV-vis and fluorescence spectral analyses of these highly fused heteroarenes were performed.

Control of Ni/Ce1-xMxOy Catalyst Properties Via the Selection of Dopant M = Gd, La, Mg. Part 1. Physicochemical Characteristics

To develop effective reforming catalyst a series of Ni catalysts (Ni content 2‒15 wt.%) supported on ceria-based oxides Ce1-xMxOy were synthesized by incipient wetness impregnation. To regulate dispersion and reducibility of the active component, the variation of chemical composition of support was performed. The prepared samples of supports and catalysts were characterized by X-ray spectral fluorescence analysis, N2 adsorption/desorption, X-ray diffraction, transmission electron microscopy, and thermal analysis. It was found that the support composition specified the forms of stabilization (NiO or Ni-M-O oxides, M = La, Mg) and capability to reduction of Ni-component through the realization of a different extent of interaction between Ni-containing species and support. The increase of M content in CexM1-xOy support induces the decrease of CexM1-xOy crystallite size, improvement of Ni active component dispersion and the increase of hard-to-reduce portion of nickel cations due to the growth in the degree of nickel- CexM1-xOy interaction. The identified variation of the textural, structural and redox characteristics of the Ni/CexM1-xOy catalysts should influence their performance in the catalytic process.

Acid pH promotes bispecific antibody formation by the redox procedure

Bispecific antibodies (BsAbs), are potential theranostics. Chemical procedures of preparation of BsAbs, in which two monospecific antibodies are split into half molecules and heterodimerized, continue to attract attention in view of their simplicity. Poor dissociation of antibodies with reduced inter-heavy chain disulfides into half molecules under neutral conditions however restricts the BsAbs formation. In this study, we report that the heterodimerization of antibodies can be improved leading to over 6-fold increase in the yield of BsAbs, by carrying out the redox procedure at pH 4.0. In view of improvement in heterodimerization, BsAbs could be conveniently prepared starting from partially purified ion-exchange fraction of the antiserum and purified by twin affinity chromatography on antigen supports. The UV, CD, intrinsic and extrinsic fluorescence spectral analysis of BsAbs prepared by the modified redox procedure were comparable with the native IgG, which suggest the absence of significant acid-pH-induced damage. ThT binding studies and native size exclusion chromatography ruled out amyloid fibril formation.

Effect of Dicarboxylic Acid Dopant on ADP Crystal by Slow Evaporation Method

Abstract Influence of dicarboxylic acid dopant on growth and characterization of ADP crystal were grown by slow evaporation technique at room temperature. The transparent (ADFU) crystals are yield after a period of 15 days. The X-ray diffraction study reveals that ADFU crystal belongs to tetragonal system. The vibrational modes of grown crystal were confirmed by FTIR spectral analysis. In UV-Vis spectral analysis the absorbance is low than pure ADP which reveals that NLO active of grown crystal is more. The emission spectrum of grown crystal was studied using fluorescence spectral analysis. The nonlinear optical property was analyzed using Kurtz-Perry technique, the SHG efficiency of ADFU crystal has much higher than that of pure ADP. The mechanical behavior includes binding nature and strength for the grown crystal was investigated by Vickers microhardness test.

Synthesis and characterization of fluorescent polyphenols anchored Schiff bases via oxidative polycondensation

Abstract A series of polyimines, bearing phenolic groups were successfully synthesized in aqueous alkaline solution via chemical oxidative polycondensation. Polymeric Schiff bases were synthesized by condensation of 2,4-dihydroxybenzaldehyde and 3-hydroxy-4-metoxybenzaldehyde with 2-aminophenol and 3-aminophenol. The molecular structures of the synthesized Schiff bases and their corresponding polymers were studied by FT-IR, UV-Vis, 1H-NMR and 13C-NMR spectroscopic methods. Thermal stability of the imine polymers was evidenced by their initial degradation temperatures found in the range of 170 °C to 271 °C without any sign of melting. The results of UV-Vis and cyclic voltammetry (CV) measurements were coherent with the optical Eg and the electrochemical E′g band gaps of the polyimines which were lower than those of their corresponding Schiff bases. Fluorescence spectral analysis of P4 (Schiff base polymer P4 derived from 3-aminophenol and 3-hydroxy-4-methoxybenzaldehyde) revealed a bicolor emission with blue and green light. Electrical conductivity of the synthesized imine polymers was measured by four-point probe technique. P4 showed the highest electrical conductivity as a result of iodine vapor contact time. Morphology characterization of the synthesized polyimines was carried out using a scanning electron microscope SEM at different magnifications. The study revealed that P4 is a promising candidate for both blue and green light emitters which could be used in the production of photovoltaic materials and solar cells.

Primer in the shots of 9 mm pistols with rectangular shapes and polygonal rifling using raster scanning electron microscopy

The paper presents the results of an experimental study using scanning scanning electron microscopy of morphological features of metal particles, burnt and semi-burnt powders, decomposition products of the initiating explosive composition of the capsule when fired with 9-mm cartridges for the gun « Fort 17 «with rectangular and» Glok 19 « polygonal shapes of the barrel cuts. The study makes it possible to clearly visualize the metal particles detected by x-ray fluorescence spectral analysis, formed during the movement of the bullet through the barrel of the weapon; to differentiate the burned powders with their subsequent drawing on a surface of a site of fire damage (damage) with those powders which were formed when carrying out a shot from firearms from a close distance. It is also established that the color of the soot determines the capsule composition of the products of the shot: gray powders are located closer to the incendiary opening of the sleeve and they are maximally covered with a capsule composition, which decomposes when it explodes and ignites the powder charge. Yellow powders are located closer to the steering wheel, and on their surface of the decomposition products of the capsule composition is very small, which does not change the color of the powders, which acted on the flame (thermal action).

Effect of Charge Basicity of Two Compositions on MnO Reduction During Smelting Ferromanganese

The effect of basicity of two different basic charges for reduction of MnO by solid carbon during smelting ferromanganese is considered. The effect of different charge compositions on MnO reduction in the temperature range 1400–1500°C is considered. Experiments are performed in a thermogravimetric furnace in the presence of CO at atmospheric pressure. X-ray spectral fluorescence analysis (XRF) of final slags is conducted with the aim of determining the degree of MnO reduction in relation to charge composition and temperature. It is established that MnO reduction depends strongly on temperature, and charge properties apparently affect reduction insignificantly.