Dimensional Fluorescence Spectra Research Articles

Probing heat and oxidation induced conformational changes of molecular chaperone artemin by excitation-emission fluorescence spectroscopy

Artemin is a potent molecular chaperone, which protects Artemia embryos undergoing encystment against extreme environmental stresses. In the present work, we have examined the structural changes of artemin from A. urmiana upon exposure to oxidant and heat, by using CD measurements as well as excitation-emission fluorescence spectroscopy as a powerful tool for monitoring the conformational transitions and molecular interactions in proteins. We have also provided here the first document on reporting the three dimensional fluorescence spectra of a protein using ANS. Totally, the fluorescence results indicated that the microenvironments of tyrosine and tryptophan residues and the hydrophobic pockets as well as the polypeptide backbone or secondary structure of the chaperone were influenced in responses to heat and H2O2 in different degrees. Moreover, the native state of artemin did not induce a considerable exposure of the internal non-polar groups to the solvent. Besides, the excitation-emission spectra of heated artemin by ANS revealed new emission peaks at 430–450 nm when it was excited at 330 nm, which suggests probable exposure of new binding sites for hydrophobic or electrostatic interactions of the protein with ANS. The protein also showed a greater conformational sensitivity to the temperature fluctuations compared to oxidation. Here, we presented some evidence in support of the relation between artemin and its stress dependent activation in vitro and in vivo. This study can expect that the EEM fluorescence spectroscopy could provide a promising tool to study conformational transitions of proteins.

Spectral characteristics and sources of rainstorms dissolved organic matter in Zhoucun Reservoir during flood season

运用三维荧光光谱（EEMs）技术结合平行因子分析法（PARAFAC），对周村水库夏季两场暴雨不同降雨历时以及分子量的溶解有机物光谱特征和来源进行分析.结果表明：周村水库不同暴雨荧光光谱中出现了5种组分，分别为类腐殖质（C1、C2）、可见区富里酸（C3）和类蛋白（C4、C5）；相关性分析显示C1与C2、C3、C4以及C5具有显著的相关性，C2与C3具有显著的相关性，C3与C4以及C5具有显著的相关性；同一分子量下的雨水有机质总荧光强度以及各组分荧光强度随着降雨历时的增加均呈下降趋势，并且在各个历时和分子量间差异明显；同一降雨历时下，第一场暴雨总荧光强度随着分子量的减少而增加，第二场暴雨总荧光强度随着分子量的减少而减少；两场暴雨都呈现自生源的特征，其中第一场暴雨具有以陆源输入为主的特征；组分C1和C3与水质参数硝态氮、氨氮、总氮以及有机碳呈显著相关性.通过对暴雨在不同降雨历时以及分子量DOM光谱特征研究，可以进一步分析水库外源输入的天然有机质特征，为水库水质管理提供技术支持.;Based on the three dimensional fluorescence spectra (EEMs) technology combined with the parallel factor analysis (PARAFAC), the spectral characteristics and sources analysis of dissolved organic matter of two rainstorms were investigated for different rainfall duration and molecular weight organic carbon in Zhoucun Reservoir. Two humic-like substances (C1, C2), one fulvic-like substance (C3) and two protein-like substance (C4, C5) were identified by PARAFAC model, and there exhibited significantly correlation coefficient in C1 & C2/C3/C4/C5, C2 & C3 and C3 & C4/C5, respectively. For the same molecular weight organic carbon, total dissolved organic matter (DOM) fluorescence intensity and the fluorescence intensity of each component showed a decreasing trend with the increase of rainfall duration and exhibited significantly differences distribution in two rainstorms. For the same rainfall duration, the total fluorescence intensity of the first rainstorm increased with the decrease of molecular weight organic carbon, while the total fluorescence intensity of the second rainstorm decreased with the decrease of molecular weight. The two rainstorms water both exhibited strong autochthonous component characteristics and first rainstorm exhibited strong terrestrial input characteristic; C1 and C3 exhibited significantly correlation coefficient with nitrate, ammonia, total nitrogen and organic carbon. From all the results, the study could supply a strong support for the managers of Zhoucun Reservoir to explore the DOM characteristic of rainstorm in the future.

Study on the interaction of graphene oxide‑silver nanocomposites with bovine serum albumin and the formation of nanoparticle-protein corona

The interaction between graphene oxide-sliver nanocomposites (GO-AgNCPs) and bovine serum albumin (BSA) in aqueous buffer solution was investigated by using several spectroscopic and imaging techniques. The visible absorbance intensity of GO-AgNCPs increased with increasing concentrations of BSA, and a slight redshift of the surface plasmon resonance band (SPR) occurred due to the absorption of BSA on the surface of GO-AgNCPs. Fluorescence data revealed a static quenching process of BSA caused by GO-AgNCPs. Thermodynamic parameters of the absorption process, including adsorption equilibrium constants, changes in Gibbs free energy (ΔG), enthalpy (ΔH) and entropy (ΔS), were evaluated at different temperatures. Negative values of ΔG showed that this process was spontaneous and the BSA-GO-AgNCPs complex might form in aqueous solution. Negative values of ΔH and ΔS suggested that the binding was mainly an enthalpy-driven process, and van der Waals forces and hydrogen bonding were the major force in the formation of the nanoparticle-protein corona. Analysis of synchronous, three dimensional (3D) fluorescence and circular dichroism (CD) spectra demonstrated that the conformation of BSA was slightly altered in the presence of GO-AgNCPs. The protein corona formed on the surface of GO-AgNCPs was directly observed by scanning probe microscopy (SPM).

Preparation, characterizations and biological evaluations of new copper(II) complexes containing ONO pincer type ligands

A new heterocyclic Schiff bases, 6‐methyl/8methyl‐2‐oxo‐1,2‐dihydroquinoline‐3‐carboxaldehyde semicarbazones (H2‐6MOQsc‐H) (H2L1) and (H2‐8MOQsc‐H) (H2L2) and their corresponding copper(II) complexes [CuCl2(H2‐6MOQsc‐H)].3H2O (1), [CuCl2(H2‐8MOQsc‐H)].3H2O (2), [CuNO3(H2‐6MOQsc‐H)(H2O)].NO3 (3) and [CuNO3(H2‐8MOQsc‐H)(H2O)].NO3 (4) have been synthesized and characterized by various physicochemical techniques. The single crystal X‐ray diffraction and spectral data revealed that all of the complexes (1‐4), the ligands coordinated to the Cu(II) ion in a neutral manner via ONO donor atoms and all the complexes exhibited distorted squarepyramidal geometry. The consequence of electronegativity and ring size of nitrogen heterocyclic moiety of ONO donor type of copper(II) chelates on nucleic acid interaction and albumin binding was investigated by in vitro experiments. The interaction of compounds with calf‐thymus DNA (CT‐DNA) has been explored by absorption and emission titration, which exposed those ligands/complexes, could bind with CT‐DNA through electrostatic interaction. The results of gel electrophoresis proved the ability of complexes (1‐4) to cleave the pBR322 plasmid DNA. The interaction of serum albumin (BSA) was investigated by UV‐Vis, fluorescence, synchronous and three dimensional fluorescence spectra. In addition, radical scavenging activity, antifungal activity and cytotoxicity of the newly synthesized compounds were also evaluated. From the results of in vitro studies, it is seen that complex 3 has more potential as compared with other complexes and ligands.

On-line analysis of algae in water by discrete three-dimensional fluorescence spectroscopy.

In view of the problem of the on-line measurement of algae classification, a method of algae classification and concentration determination based on the discrete three-dimensional fluorescence spectra was studied in this work. The discrete three-dimensional fluorescence spectra of twelve common species of algae belonging to five categories were analyzed, the discrete three-dimensional standard spectra of five categories were built, and the recognition, classification and concentration prediction of algae categories were realized by the discrete three-dimensional fluorescence spectra coupled with non-negative weighted least squares linear regression analysis. The results show that similarities between discrete three-dimensional standard spectra of different categories were reduced and the accuracies of recognition, classification and concentration prediction of the algae categories were significantly improved. By comparing with that of the chlorophyll a fluorescence excitation spectra method, the recognition accuracy rate in pure samples by discrete three-dimensional fluorescence spectra is improved 1.38%, and the recovery rate and classification accuracy in pure diatom samples 34.1% and 46.8%, respectively; the recognition accuracy rate of mixed samples by discrete-three dimensional fluorescence spectra is enhanced by 26.1%, the recovery rate of mixed samples with Chlorophyta 37.8%, and the classification accuracy of mixed samples with diatoms 54.6%.

Assessment of the content, structure, and source of soil dissolved organic matter in the coastal wetlands of Jiaozhou Bay, China

The contents and the spectral analysis of dissolved organic matter (DOM) in four typical wetlands, such as naked tidal, suaeda salsa, reed and spartina, were conducted to investigate the content, structure, and source of DOM in coastal wetland soil. The soil samples were obtained from Jiaozhou Bay in January, April, July, and October of 2014. Results showed that the DOM contents in soil of four typical wetland were in order of spartina wetland > naked tidal > suaeda salsa wetland > reed wetland in horizontal direction, and decreased with the increase of soil depth on vertical section. In addition, the DOM contents changed with the seasons, in order of spring > summer > autumn > winter. The structural characteristics of DOM in Jiaozhou Bay wetland, such as aromaticity, hydrophobicity, molecular weight, polymerization degree of benzene ring carbon frame structure and so on were in order of spartina wetland > naked tidal > suaeda salsa wetland > reed wetland in the horizontal direction. On the vertical direction, they showed a decreasing trend with the increase of soil depth. The results of three dimensional fluorescence spectra and fluorescence spectrum parameters (FI, HIX, and BIX) indicated that the DOM in Jiaozhou Bay was mainly derived from the biological activities. The contents and structure of DOM had certain relevance, but the contents and source as well as the structure and source of DOM had no significant correlation. The external pollution including domestic sewage, industrial wastewater, and aquaculture sewage affected the correlation among the content, structure and source of DOM by influencing the percentage of non-fluorescent substance in DOM and disturbing the determination of protein-like fluorescence.

Characteristics of three dimensional fluorescence spectra and its correlation with water quality in Jinghe and Bortala River from Lake Ebinur's major inflow tributaries,Xinjiang

Characteristics of three dimensional fluorescence spectra and its correlation with water quality in Jinghe and Bortala River from Lake Ebinur's major inflow tributaries,Xinjiang

矿物油三维荧光谱的小波变换奇异值特征

矿物油三维荧光谱的小波变换奇异值特征

Analysis of spatial distribution characteristics of dissolved organic matter in typical greenhouse soil of northern China using three dimensional fluorescence spectra technique and parallel factor analysis model.

The aim of the present work is to study the soil DOM characteristics in the vegetable greenhouse with a long-term of cultivation. Results showed that the soil DOM mainly consisted of three components, fulvic acid-like (C1), humic acid-like (C2) and protein-like (C3), with C1 as the majority one. The distribution of DOM in space was also studied. In vertical direction, C1 and C2 decreased significantly with the increase in soil depth, while C3 component decreased after increased. The humification coefficient decreased fast from 0-20 to 30-40 cm, and then increased from 30-40 to 40-50 cm. In the horizontal direction, the level of C2 component varied greatly in space, while that of C1 component changed little, and that of C3 component fell in between the above two. The change in the humification degree of each soil layer significantly varied spatially. Humification process of soil organic matter mainly occurred in the surface soil layer. In addition, the humification degree in space also changed significantly. The new ideas of this study are: (1) Analyze the composition and spatial heterogeneity of soil DOM in the vegetable greenhouse; (2) Use three dimensional fluorescence spectra technology and parallel factor analysis model successfully to quantify the components of soil DOM, which provides a new method for the soil DOM analysis.

基于三维荧光谱降维处理的矿物油识别研究

基于三维荧光谱降维处理的矿物油识别研究

Discrimination of three dimensional fluorescence spectra based on wavelet analysis and independent component analysis

Fluorescence spectroscopy is a rapid and non-destructive method for monitoring water quality. In this work, wavelet analysis, together with independent component analysis (ICA), was applied for component recognition of seriously overlapped, multi-component, three dimensional fluorescence spectra. Wavelet analysis extracts the features of the spectra and amplifies differences among phenolic homologs. ICA analysis in blind signal separation was used to separate single component before multiple linear regression (MLR). The proposed method increases the correct classification rate and enriches the spectra library. As such, it is a useful alternative to traditional techniques in component recognition.

Impacts of irrigation with industrial treated wastewater on soil properties

Wastewater reuse in agriculture is a widespread practice in developing countries, especially in urban areas where water shortage and poverty encourage people to use that marginal resource. Raw or treated wastewaters are used by farmers, but even treated wastewaters frequently do not meet WHO and FAO standards for irrigation water. Such practices may lead to health hazards, relatively well documented in the literature and to environmental damages. Adverse environmental impacts such as soil degradation and groundwater contamination are frequently associated with the use of wastewater from industrial sources. Previous studies have demonstrated that wastewater irrigation may decrease soil hydraulic conductivity and infiltration rate. Nevertheless, the effects on soil structural and chemical behaviors have been little studied so far and need further investigations.The impacts of irrigation with alkaline and sodic industrial wastewater previously treated in microphyte ponds on soil physical and chemical properties were studied downstream the sewage treatment plant of Kossodo in Ouagadougou, on plots cropped with eggplants. Plots irrigated with fresh water and non cropped, non irrigated plots were used as controls.Different soil properties were characterized: pore volumes determined by using shrinkage analysis, pH and electrical conductivity of water extracts, and major soluble and exchangeable cations (Ca, Mg, K, and Na). Organic matter characterization was performed by means of three dimensional fluorescence spectra analysis to determine its origin and evolution on irrigated soils.Plots irrigated with wastewater showed important structural damages, especially in the subsurface horizon where the soil pore network collapsed dramatically, resulting in a compact impermeable layer. Fluorescence spectra revealed that the organic matter contained in the wastewater was largely dissolved due to a sharp soil pH increase, resulting in black alkali formation at the surface; the soil became sodic, with an exchange complex dominated by sodium, whereas plots irrigated with fresh water kept properties comparable to that of non irrigated plots. Such a rapid soil sodication was seldom reported so far. The study emphasizes the need to carefully examine irrigation water quality and particularly calcite residual alkalinity and suggests that shrinkage analysis could be used to monitor the physical changes of soil properties upon sodication. Inadequate wastewater quality is likely to cause deep and irreversible damages to irrigated soils.

Adsorption property of direct fast black onto acid-thermal modified sepiolite and optimization of adsorption conditions using Box-Behnken response surface methodology

The adsorption of direct fast black onto acid-thermal modified sepiolite was investigated. Batch adsorption experiments were performed to evaluate the influences of experimental parameters such as initial dye concentration, initial solution pH and adsorbent dosage on the adsorption process. The three-factor and three-level Box-Behnken response surface methodology (RSM) was utilized for modeling and optimization of the adsorption conditions for direct fast black onto the acid-thermal modified sepiolite. The raw sepiolite was converted to acid-thermal modified sepiolite, and changes in the fourier transform infrared spectrum (FTIR) adsorption bands of the sample were noted at 3435 cm−1 and 1427 cm−1. The zeolitic water disappeared and the purity of sepiolite was improved by acid-thermal modification. The decolorization rate of direct fast black adsorbed increased from 68.2% to 98.9% on acid-thermal modified sepiolite as the initial solution pH decreased from 10 to 2. When the adsorbent dosage reached to 2.5 g·L−1, 2.0 g·L−1, 1.5 g·L−1 and 1.0 g·L−1, the decolorization rate was 90.3%, 86.7%, 61.0% and 29.8%, respectively. When initial dye concentration increased from 25 to 200 mg·L−1, the decolorization rate decreased from 91.9% to 60.0%. The RSM results showed that the interaction between adsorbent dosage and pH to be a significant factor. The optimum conditions were as follows: the adsorbent dosage 1.99 g·L−1, pH 4.22, and reaction time 5.2 h. Under these conditions, the decolorization rate was 95.1%. The three dimensional fluorescence spectra of direct fast black before and after treatment showed that the direct fast black was almost all adsorbed by the acid-thermal modified sepiolite.

Conformation and Thermodynamic Properties of the Binding of Vitamin C to Human Serum Albumin

The binding of vitamin C, L-ascorbic acid (AsA), with human serum albumin (HSA) was investigated by various spectroscopic techniques under simulated physiological conditions. The fluorescence quenching constants (K SV) at four different temperatures (292, 298, 304, and 310 K) were obtained. The thermodynamic parameters ΔH ∘ and ΔS ∘ were calculated to be 6.02 kJ⋅mol−1 and 84.55 J⋅mol−1⋅K−1 using the van’t Hoff equation. Additional experiments to determine the stoichiometry (n) were carried out using isothermal titration calorimetry (ITC) and cyclic voltammetry (CV). The distance, r, between AsA and the tryptophan residues of HSA was calculated to be 3.7 nm according to Forster’s non-radiation energy transfer theory. The effect of AsA on the conformation of HSA was studied by means of three dimensional fluorescence spectra and CD spectra. The results indicate that the presence of AsA resulted in a slight change of the HSA secondary structure. The effect of common ions on the binding of AsA to HSA was also examined.

Spectroscopic Investigation on the Interaction of Pyrimidine Derivative, 2-Amino-6-hydroxy-4-(3,4-dimethoxyphenyl)-pyrimidine-5-carbonitrile with Human Serum Albumin: Mechanistic and Conformational Study

In the present study, fluorescence spectroscopy in combination with UV–vis absorption spectroscopy and synchronous fluorescence spectroscopy (SFS) was employed to investigate the binding affinity of pyrimidine derivative, 2-amino-6-hydroxy-4-(3,4-dimethoxyphenyl)-pyrimidine-5-carbonitrile (AHDMPPC) to human serum albumin (HSA) under the physiological conditions. In the mechanism discussion, it was proved that the fluorescence quenching of HSA by AHDMPPC is a result of the formation of AHDMPPC–HSA complex. The quenching mechanism and number of binding sites (n ≈ 1) were obtained by fluorescence titration data. Binding parameters calculated from Stern–Volmer method showed that the AHDMPPC bind to HSA with the binding affinities of the order 104 L mol–1. The thermodynamic parameters studies revealed that the binding was characterized by negative enthalpy and positive entropy changes −13.06 kJ/mol and 51.34 J/mol K–1 (from the Van’t Hoff equation) and suggest that the binding reaction was exothermic and hydrophobic interaction is the predominant intermolecular forces stabilizing the complex. The specific binding distance (r = 2.25 nm) between donor HSA and acceptor AHDMPPC was obtained according to fluorescence resonance energy transfer (FRET). Furthermore, the synchronous spectral result, three–dimensional fluorescence spectra and circular dichroism (CD) indicates that the secondary structure of HSA was changed in the presence of AHDMPPC.

A novel initialization method for nonnegative matrix factorization and its application in component recognition with three-dimensional fluorescence spectra

Nonnegative matrix factorization has been widely used in many areas and has been applied for component recognition with three dimensional fluorescence spectra recently. However, nonnegative matrix factorization is a nonconvex programming in the iteration process, thus the solution is dependent on the initial values and consequently not unique. Up to now, an effective global convergent algorithm is still absent. In this work, we propose an initialization scheme based on independent component analysis. Compared with other initialization schemes, the optimal solution of nonnegative matrix factorization based on independent component analysis is much better and it is demonstrated by typical experiments of component recognition with three-dimensional fluorescence spectra.

Spectroscopic probe analysis for exploring probe–protein interaction: A mapping of native, unfolding and refolding of protein bovine serum albumin by extrinsic fluorescence probe

Steady state and dynamic fluorescence measurements have been used to investigate interaction between Bovine Serum Albumin (BSA) and fluorescence probe para-N,N-dimethylamino orthohydroxy benzaldehyde (PDOHBA), a structurally important molecule exhibiting excited state coupled proton transfer (PT) and charge transfer (CT) reaction. Fluorescence anisotropy, acrylamide quenching, and time resolved fluorescence measurements corroborate the binding nature of the probe with protein. The binding constant between BSA and PDOHBA has been determined by using Benesi–Hildebrand and Stern–Volmer equations. The negative value of ΔG indicates the spontaneity of this probe–protein complexation process. Observations from synchronous, three dimensional fluorescence spectra and circular dichroism spectra point toward the fact that the hydrophobicity as well as α-helix content of BSA are altered in presence of probe PDOHBA. The PT band of PDOHBA is found to be an excellent reporter for the mapping of destructive and protective behavior of SDS with variation of chaotrope concentration.

Studying the humification degree and evolution of peat down a Holocene bog profile (Inuvik, NW Canada): A petrological and chemical perspective

The process of the transformation of fresh organic matter (OM) into more stable and recalcitrant humic substances is still not completely clear. Understanding how OM humification evolves in northern bog environments is extremely important, especially considering that they represent one of the largest terrestrial carbon pools. Structural changes of OM occurring during the humification process have been generally evaluated by indirect measurements of the degree of humification. Several approaches have been used, often providing contrasting results probably because humification is a complex process that evolves differently according to varying pedoclimatic conditions. In the present work, the authors followed the evolution of peat OM along a 165 cm bog profile (covering the mid- to late Holocene) correlating results obtained from both organic petrological and chemical investigation. Data clearly underline a significant agreement between the two perspectives, both showing either a quite immature peat material or the presence of three distinct zones along the profile. In detail, both spectroscopic (i.e., FT-IR and three dimensional fluorescence spectra, humification indexes), and Rock–Eval pyrolysis results (low residual organic carbon content and high hydrogen and oxygen index values) showed the occurrence of a central zone (from 20–30 cm to 120 cm depth) often characterized by high heterogeneity and a low degree of humification when compared to the upper ∼20 and bottom 40 cm sections.

Measuring 3D fluorescence spectra of phytoplankton using an ocean lidar

In order to obtain the three dimensional (3D) fluorescence spectra directly and rapidly by in situ and in vivo phytoplankton monitoring, a prototype ocean lidar system with the ability of measuring 3D fluorescence spectra is developed, in which an optical parametric oscillator (OPO) and a grating spectrometer are employed. Using the system, the 3D fluorescence spectra of five typical red-tide species in the East China Sea are measured in lab. The preliminary experimental results show the feasibility of monitoring and classifying phytoplankton by this ocean lidar.

Fluorescence study on Interactions of α–Crystallin with the Molten Globule State of 1, 4–β–D–Glucan Glucanohydrolase from Thermomonospora sp. induced by guanidine hydrochloride

In this paper, the interaction between alpha- crystallin and molten globule structure of 1,4-beta-D-Glucan Glucohydrolase (TSC) from an alkalothermophilic Thermomonospora sp. was investigated mainly by fluorescence quenching spectra, circular dichroism and three dimensional fluorescence spectra under simulative physiological conditions. Denaturation studies using GdnCl indicated that TSC folds through a partially folded state that resembles molten globule at 1.8 M GdnCl. The chaperone activity of alpha- crystallin was employed to study refolding of TSC. Here we studied the refolding of GdnCl denatured TSC from its molten globule state (TSC-m complex) in the presence and absence of alpha-crystallin to elucidate the molecular mechanism of chaperone-mediated in vitro folding. Our results, based on intrinsic tryptophan fluorescence and ANS binding studies, suggest that alpha-crystallin formed a complex with a putative intermediate molten globule-like intermediate in the refolding pathway of TSC. Reconstitution of the active TSC was observed on cooling the alpha-crystallin * TSC-m complex to 4 degrees C. Addition of alpha-crystallin to the molten globule-like intermediate of TSC (TSC-m complex) complex initiated the refolding of TSC with 69% recovery of the biological activity of the enzyme.