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1.
Phys Chem Chem Phys ; 21(41): 22700-22703, 2019 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-31579899

RESUMO

We use cold ion spectroscopy and quantum-chemical computations to solve the structures of opioid peptides enkephalins in the gas phase. The derived structural parameters clearly correlate with the known pharmacological efficiency of the studied drugs, suggesting that gas-phase methods, perhaps, can be used for predicting the relative potency of ligand drugs that target the hydrophobic pockets of receptors.


Assuntos
Encefalinas/química , Gases/química , Modelos Moleculares , Análise Espectral , Encefalinas/farmacologia , Humanos , Interações Hidrofóbicas e Hidrofílicas , Neurotransmissores/química , Neurotransmissores/farmacologia , Relação Estrutura-Atividade
2.
Phys Chem Chem Phys ; 21(41): 22782-22793, 2019 Oct 24.
Artigo em Inglês | MEDLINE | ID: mdl-31595896

RESUMO

The theoretical assignment of electronic spectra of polyatomic molecules is a challenging problem that requires the specification of the character of a large number of electronic states. We propose a procedure for automatically determining the character of electronic transitions and apply it to the study of UV spectra of DNA bases in the gas phase and in the aqueous environment. The procedure is based on the computation of electronic wave function overlaps and accounts for an extensive sampling of nuclear geometries. Novelties of this work are the theoretical assignment of the electronic spectra of DNA bases up to 190 nm and a state specific analysis of solvation effects. By accounting for different effects contributing to the total solvent shift we obtained a good agreement between the computed and experimental spectra. Effects of vibrational averaging, temperature and solvent-induced structural changes shift excitation energies to lower values. Solvent-solute electrostatic interactions are state specific and strongly destabilize nRyd states, and to lesser extent nπ* and πRyd states. Altogether, this results in the stabilization of ππ* states and destabilization of nπ*, πRyd and nRyd states in solution.


Assuntos
Técnicas de Química Analítica/métodos , DNA/química , Solventes/química , Análise Espectral , Gases/química , Eletricidade Estática , Raios Ultravioleta
3.
Chemosphere ; 235: 1154-1161, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31561306

RESUMO

A MBBR-MBR system has been developed with marine microorganisms enriched for saline wastewater treatment in this work, showing high COD and NH3-N removals. The behaviour of fouling-related components (EPS and SMP) has been studied as functions of operating time (40-90 days), salinity (0-30 g/L NaCl) and backflow ratio (0-300%, from MBR to MBBR). High biodegradability of the MBBR-MBR at optimal conditions can induce more biodegradation of humic acid-like (λex/λem: 350nm/430 nm) and fulvic acid-like (260nm/445 nm) molecules to soluble microbial by-product-like molecules (275nm/325 nm), reducing the membrane biofouling rate. The biodegradation process is suggested by the excitation-emission matrix (EEM) images. In the study of sudden salinity shock, results show that real-time monitoring the concentration of biofoulants is more effective (operative time extended by 60%) than monitoring the transmembrane pressure (operative time extended by 33%) to prevent membrane fouling. Due to an early warning from the real-time monitoring, the coming membrane-fouling is predictable and the operating conditions, such as backflow ratio, can be changed to minimize the biofouling rate.


Assuntos
Biofilmes , Incrustação Biológica/prevenção & controle , Reatores Biológicos , Membranas Artificiais , Águas Residuárias/química , Biodegradação Ambiental , Salinidade , Análise Espectral , Purificação da Água/métodos
4.
J Phys Chem Lett ; 10(20): 6105-6111, 2019 Oct 17.
Artigo em Inglês | MEDLINE | ID: mdl-31549842

RESUMO

Protein-protein interactions (PPIs) play a pivotal role in many biological processes. Discriminating functionally important well-defined protein-protein complexes formed by specific interactions from random aggregates produced by nonspecific interactions is therefore a critical capability. While there are many techniques which enable rapid screening of binding affinities in PPIs, there is no generic spectroscopic phenomenon which provides rapid characterization of the structure of protein-protein complexes. In this study we show that chiral plasmonic fields probe the structural order and hence the level of PPI specificity in a model antibody-antigen system. Using surface-immobilized Fab' fragments of polyclonal rabbit IgG antibodies with high specificity for bovine serum albumin (BSA), we show that chiral plasmonic fields can discriminate between a structurally anisotropic ensemble of BSA-Fab' complexes and random ovalbumin (OVA)-Fab' aggregates, demonstrating their potential as the basis of a useful proteomic technology for the initial rapid high-throughput screening of PPIs.


Assuntos
Fragmentos Fab das Imunoglobulinas/metabolismo , Imunoglobulina G/metabolismo , Nanoestruturas/química , Cimento de Policarboxilato/química , Soroalbumina Bovina/metabolismo , Animais , Anisotropia , Bovinos , Ouro/química , Fragmentos Fab das Imunoglobulinas/imunologia , Imunoglobulina G/imunologia , Ovalbumina/imunologia , Ovalbumina/metabolismo , Ligação Proteica , Coelhos , Soroalbumina Bovina/imunologia , Análise Espectral/métodos , Estereoisomerismo
5.
Artigo em Chinês | MEDLINE | ID: mdl-31495121

RESUMO

Objective: To establish a method for determination of lead and istope ratios in the blood by ISIS-ICP-MS. Methods: After wet digestion, the blood sample was on-line addition of thallium as internal standard and analyzed by ISIS-ICP-MS. Results: The limit of detection was 0.03 µg/L and the lower limit of quantification was 0.08 µg/L. The detection concentration was 0.45 µg/L and the minimum quantitative concentration was 1.49 µg/L. The relative standard deviations (RSD) were 0.3%~1.7%. The recovery was between 91.0% and 103.4%. The precision of the major lead isotope ratios was better than 0.3%. The calibrated isotope ratios of the standard liquid are close to the certificate. Conclusion: The method has a low detection limit, good precision and high accuracy, it is feasible for determination of lead concentration and isotope ratios in the bloune.


Assuntos
Chumbo/sangue , Espectrometria de Massas , Humanos , Isótopos/sangue , Limite de Detecção , Análise Espectral
7.
Phys Chem Chem Phys ; 21(37): 20678-20692, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31508628

RESUMO

In this work we present a high-throughput approach to the computation of absorption UV-Vis spectra tailored to mutagenesis studies. The scheme makes use of a single molecular dynamics trajectory of a reference (non-mutated) species. The shifts in absorption energy caused by a residue mutation are evaluated by building an effective potential of the environment and computing a correction term based on perturbation theory. The sampling is only performed in the phase space of the initial protein. We analyze the robustness of the method by comparing different approximations for the effective potential, the sampling of mutant residue geometries and observing the impact in the prediction of both bathocromic and hypsochromic shifts. As a test subject, we consider a red fluorescent protein variant with potential biotechnological applications.


Assuntos
Testes Genéticos/métodos , Luz , Proteínas/química , Proteínas/genética , Análise Espectral , Raios Ultravioleta , Simulação de Dinâmica Molecular , Mutação
8.
Phys Chem Chem Phys ; 21(37): 20606-20612, 2019 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-31528919

RESUMO

In this work, the interaction between an Auramine O (AuO) fluorescent molecular rotor and natural DNA, its thermodynamic aspects and the resulting variation of the optical properties upon binding are addressed by a combined spectroscopic (UV-vis and fluorescence) and computational approach. DNA binding causes a shift in the maximum of absorption from 432 nm to 444 nm, a decrease of the extinction coefficient and a dramatic enhancement of fluorescence emission, these results being in agreement with intercalation into the polynucleotide helix. Intercalation is indeed confirmed by the thermodynamic parameters for the binding reaction (in particular, the highly negative ΔH). Theoretical modelling at the TD-DFT level was done on a simplified model system consisting of the AuO molecule intercalated between two DNA base pairs. The evolution of the calculated vertical transitions quantitatively reproduces the experimentally observed hypo- and bathochromic shifts, thus confirming the intercalation hypothesis.


Assuntos
Benzofenoneídio/química , DNA/química , Modelos Químicos , Análise Espectral , Fluorescência , Simulação de Dinâmica Molecular
9.
Chemistry ; 25(53): 12298-12302, 2019 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-31386225

RESUMO

Oligonucleotide-based therapeutics have made rapid progress in clinical treatment of a variety of disease indications. Since most therapeutic oligonucleotides serve more than just one function and tend to have a prolonged lifetime, spatio-temporal control of these functions would be desirable. Photoswitches like azobenzene have proven themselves as useful tools in this matter. Upon irradiation, the photoisomerization of the azobenzene moiety causes destabilization in adjacent base pairs, leading to a decreased hybridization affinity. Since the way the azobenzene is incorporated in the oligonucleotide is of utmost importance, we synthesized locked azobenzene C-nucleosides and compared their photocontrol capabilities to established azobenzene C-nucleosides in oligonucleotide test-sequences by means of fluorescence-, UV/Vis-, and CD-spectroscopy.


Assuntos
Compostos Azo/química , Nucleosídeos/química , Oligonucleotídeos/química , Pareamento de Bases , Hibridização Genética , Hibridização de Ácido Nucleico , Análise Espectral
10.
J Cosmet Sci ; 70(4): 209-216, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31441774

RESUMO

Dimethicone is a mixture of fully methylated linear siloxane polymers of various molecular weights. This water-insoluble ingredient provides exceptional skin protection and lubrication when incorporated into skin and hair care products. Quantitative analysis of dimethicone is often required to support quality assurance testing of finished products. We report a new, rapid analytical method based on Fourier transform infrared spectrometry, using a special attenuated total reflectance cell to determine concentrations of dimethicone directly in aqueous emulsions present in personal care products. This rapid, simplified method eliminates sample preparation to remove water, while providing reliable results across a wide range of dimethicone concentrations.


Assuntos
Análise Espectral , Dimetilpolisiloxanos , Emulsões , Água
11.
Environ Pollut ; 253: 181-189, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31306825

RESUMO

This work explores the use of Raman micro-spectroscopy to determine sources of airborne particulate matter collected on PM2.5 air filters in Imperial Valley, California. The goal is to examine if nearby soil is a potential source of particles sampled on air filters deployed in an urbanized desert area during events of unusually high PM2.5 excursions. Particle specific composition information can be an indicator of potential origin. This can provide insights into the source of unexpectedly high proportion of large particles sampled on PM2.5 filters in the vicinity of Imperial Valley. The measured spectral correspondence between the filter and soil particles, in the size range of 2.5-10 µm, is consistent with windblown dust being a likely source of the larger (>2.5 µm) particles collected on the PM2.5 filters. Additionally, these particles were identified as components of commonly occurring crustal minerals in the vicinity of the sampling site, such as iron oxides, hydroxides, sulfides, titanium dioxides and aluminosilicates. A substantial portion of the analyzed filter particles displayed a strong broadband fluorescence signal, which is consistent with the presence of organic matter and has been recognized as a marker for soil related origin of the filter particles. Elemental carbon (soot) was found to be prevalent among the particles as well, suggesting the existence of combustion related sources. Comparison between a heavily loaded filter sample and a filter with a more typical, lower loading did not show any obvious difference in chemical compositions. In both cases the particles appeared to be of crustal origin with the prevalence of elemental carbon. The primary difference between these two filter samples appear to be their particle size distribution - the heavily loaded filter sample contained greater proportion of large particles (>2.5 µm), and was more consistent with spectral signature of soils analyzed from the region.


Assuntos
Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Material Particulado/análise , Solo , Filtros de Ar , Poluição do Ar/análise , Poluição do Ar/estatística & dados numéricos , California , Carbono/análise , Poeira/análise , Tamanho da Partícula , Análise Espectral
12.
Ecol Lett ; 22(10): 1608-1619, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31347263

RESUMO

Both niche and stochastic dispersal processes structure the extraordinary diversity of tropical plants, but determining their relative contributions has proven challenging. We address this question using airborne imaging spectroscopy to estimate canopy ß-diversity for an extensive region of a Bornean rainforest and challenge these data with models incorporating niches and dispersal. We show that remotely sensed and field-derived estimates of pairwise dissimilarity in community composition are closely matched, proving the applicability of imaging spectroscopy to provide ß-diversity data for entire landscapes of over 1000 ha containing contrasting forest types. Our model reproduces the empirical data well and shows that the ecological processes maintaining tropical forest diversity are scale dependent. Patterns of ß-diversity are shaped by stochastic dispersal processes acting locally whilst environmental processes act over a wider range of scales.


Assuntos
Biodiversidade , Ecossistema , Floresta Úmida , Análise Espectral , Bornéu , Tecnologia de Sensoriamento Remoto , Clima Tropical
13.
Food Chem ; 299: 125051, 2019 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-31284245

RESUMO

This study aims to exploit the molecular and cellular mechanisms concerning the functionality of dietary polyphenols (catechin, procyanidin B3, procyanidin C2, epigallocatechin and epigallocatechin gallate) in a nutritional context to prevent Celiac Disease (CD). In that sense, the interaction between the main CD bioactive peptide (32-mer peptide) and some polyphenols was fully characterized at the intestinal level under near physiological conditions by means of different spectroscopic techniques and dynamic simulations. Accordingly, it is proposed that the primarily polyphenol-binding sites on the 32-mer peptide correspond to leucine, tyrosine and phenylalanine containing domains being this interaction entropy-driven. Although procyanidin B3 and trimer C2 had a similar low-affinity constant at 310 K, both procyanidins were able to reduce the 32-mer peptide apical-to-basolateral translocation in in vitro simulated intestinal epithelial barrier thus prospecting the occurrence of additional and still unexplored regulatory mechanisms by which dietary polyphenols might modulate the transepithelial transport of CD bioactive peptides.


Assuntos
Alimentos , Glutens/química , Fragmentos de Peptídeos/química , Polifenóis/química , Análise Espectral , Glutens/metabolismo , Mucosa Intestinal/metabolismo , Fragmentos de Peptídeos/metabolismo , Ligação Proteica , Transporte Proteico
14.
J Chem Phys ; 151(1): 015101, 2019 Jul 07.
Artigo em Inglês | MEDLINE | ID: mdl-31272172

RESUMO

We use extended depolarized light scattering spectroscopy to study the dynamics of water in a lysozyme-trehalose aqueous solution over a broad time scale, from hundreds to fractions of picoseconds. We provide experimental evidence that the sugar, present in the ternary solution in quantity relevant for biopreservation, strongly modifies the solvation properties of the protein. By comparing aqueous solutions of lysozyme with and without trehalose, we show that the combined action of sugar and protein produces an exceptional dynamic slowdown of a fraction of water molecules around the protein, which become more than twice slower than in the absence of trehalose. We speculate that this ultraslow water may be caged between the sugar and protein surface, consistently with a water entrapment scenario. We also demonstrate that the dynamics of these water molecules gets slower and slower upon cooling. On the basis of these findings, we believe such ultraslow water close to the lysozyme is likely to be involved in the mechanism of bioprotection.


Assuntos
Luz , Muramidase/química , Espalhamento de Radiação , Análise Espectral/métodos , Trealose/química , Água/química
15.
Phys Chem Chem Phys ; 21(28): 15779-15786, 2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31282523

RESUMO

Small-molecule fluorescent probes having optimized optical properties, such as high photostability and brightness, local microenvironment sensitivity and specific subcellular localizations, are increasingly available. Although the basis for designing efficient fluorophores for bioimaging applications is well established, implementing an improvement in a given photophysical characteristic always tends to compromise another optical property. This problem has enormous consequences for in vivo imaging, where ensuring a specific localization and precise control of the probe response is challenging. Herein we discuss a fluorescent probe, CC334, as a case study of the chromenylium-cyanine family that commonly exhibits highly complex photophysical schemes and highly interfered bioanalytical responses. By an exhaustive and concise analysis of the CC334 optical responses including detailed spectroscopic calibrations, steady-state microenvironment effects, ultrafast photophysics analysis and computational studies, we elucidate a new strategy to apply the probe in the singlet oxygen reactive oxygen species (1O2-ROS) monitoring using in vitro and in vivo models. The probe provides a new avenue for designing fluorescent probes to understand the dynamic behavior of subcellular environments.


Assuntos
Benzopiranos/química , Corantes Fluorescentes/química , Corantes Fluorescentes/metabolismo , Cobalto/química , Ferrocianetos/química , Quinolinas/química , Espécies Reativas de Oxigênio/química , Análise Espectral
17.
J Enzyme Inhib Med Chem ; 34(1): 1259-1270, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31287341

RESUMO

Pyrazolylphthalimide derivative 4 was synthesized and reacted with different reagents to afford the target compounds imidazopyrazoles 5-7, pyrazolopyrimidines 9, 12, 14 and pyrazolotriazines 16, 17 containing phthalimide moiety. The prepared compounds were established by different spectral data and elemental analyses. Additionally, all synthesized derivatives were screened for their antibacterial activity against four types of Gram + ve and Gram-ve strains, and for antifungal activity against two fungi micro-organisms by well diffusion method. Moreover, the antiproliferative activity was tested for all compounds against human liver (HepG-2) cell line in comparison with the reference vinblastine. Moreover, drug-likeness and toxicity risk parameters of the newly synthesized compounds were calculated using in silico studies. The data from structure-actvity relationship (SAR) analysis suggested that phthalimide derivative bearing 3-aminopyrazolone moiety, 4 illustrated the best antimicrobial and antitumor activities and might be considered as a lead for further optimization. To investigate the mechanism of the antimicrobial and anticancer activities, enzymatic assay and molecular docking studies were carried out on E. coli topoisomerase II DNA gyrase B and VEGFR-2 enzymes.


Assuntos
Ftalimidas/química , Ftalimidas/farmacologia , Antibacterianos/síntese química , Antibacterianos/química , Antibacterianos/farmacologia , Antifúngicos/síntese química , Antifúngicos/química , Antifúngicos/farmacologia , Ensaios de Seleção de Medicamentos Antitumorais , Células Hep G2 , Humanos , Testes de Sensibilidade Microbiana , Simulação de Acoplamento Molecular , Ftalimidas/síntese química , Análise Espectral/métodos , Relação Estrutura-Atividade
18.
Food Chem ; 297: 124960, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31253301

RESUMO

Rice is the most consumed food worldwide, therefore its designation of origin (PDO) is very useful. Laser-induced breakdown spectroscopy (LIBS) is an interesting analytical technique for PDO certification, since it provides fast multielemental analysis requiring minimal sample treatment. In this work LIBS spectral data from rice analysis were evaluated for PDO certification of Argentine brown rice. Samples from two PDOs were analyzed by LIBS coupled to spark discharge. The selection of spectral data was accomplished by extreme gradient boosting (XGBoost), an algorithm currently used in machine learning, but rarely applied in chemical issues. Emission lines of C, Ca, Fe, Mg and Na were selected, and the best performance of classification were obtained using k-nearest neighbor (k-NN) algorithm. The developed method provided 84% of accuracy, 100% of sensitivity and 78% of specificity in classification of test samples. Furthermore, it is simple, clean and can be easily applied for rice certification.


Assuntos
Análise de Alimentos/métodos , Oryza/química , Análise Espectral/métodos , Algoritmos , Argentina , Análise de Alimentos/estatística & dados numéricos , Lasers , Metais/análise , Metais/química , Análise Espectral/estatística & dados numéricos
19.
Environ Pollut ; 252(Pt B): 1117-1124, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31252109

RESUMO

The heavy metal concentration of soil samples often exhibits a skewed distribution, especially for soil samples from mining areas with an extremely high concentration of heavy metals. In this study, to model soil contamination in mining areas using reflectance spectroscopy, the skewed distribution was corrected and heavy metal concentration estimated. In total, 46 soil samples from a mining area, along with corresponding field soil spectra, were collected. Laboratory spectra of the soil samples and the field spectra were used to estimate copper (Cu) concentration in the mining area. A logarithmic transformation was used to correct the skewed distribution, and based on the sorption of Cu on spectrally active soil constituents, the spectral bands associated with iron oxides were extracted from the visible and near-infrared (VNIR) region and used in the estimation. A genetic algorithm was adopted for band selection, and partial least squares regression was used to calibrate the estimation model. After transforming the distribution of Cu concentration, the accuracies (R2) of the estimation of Cu concentration using laboratory and field spectra separately were 0.94 and 0.96. The results indicate that Cu concentration in the mining area can be estimated using reflectance spectroscopy following correction of skewed distribution.


Assuntos
Monitoramento Ambiental/métodos , Metais Pesados/análise , Mineração , Poluentes do Solo/análise , Calibragem , Poluição Ambiental/estatística & dados numéricos , Análise dos Mínimos Quadrados , Solo/química , Análise Espectral
20.
Environ Pollut ; 252(Pt B): 1125-1132, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31252110

RESUMO

Knowledge of distribution of toxic metal in crop is essential for studying toxic metal uptake, transportation and bioaccumulation, and it is important for environmental pollution monitoring. In this study, the macro spatial distribution of chromium in rice leaves was visualized by re-heating dual-pulse laser-induced breakdown spectroscopy (DPLIBS) and chemometric methods. After the optimization of two important parameters (delay time and energy ratio) in DPLIBS, chromium prediction model was established based on global spectra. The global model achieved acceptable performance while slight overfitting for model was found because of numerous irrelevant variables. Feature variables including emissions from chromium and other elements were successfully selected by the values of regression coefficient in partial least square regression model. Best performance was achieved by using the feature variables and support vector machine, with correlation coefficient of prediction of 0.959, root mean square error of prediction of 13.4 mg/kg and residual predictive deviation of 3.6. Finally, the distribution of chromium in rice leaves was visualized with the best prediction model. The distribution image showed that chromium distributed approximately symmetrically along the vein and was likely to be accumulated in leaf apex. The preliminary results provide an approach for investigating the macro spatial distribution of elements in crops, which is important for environmental protection and food safety.


Assuntos
Cromo/análise , Lasers , Oryza/química , Poluentes do Solo/análise , Produtos Agrícolas/química , Monitoramento Ambiental/métodos , Calefação , Análise dos Mínimos Quadrados , Luz , Folhas de Planta/química , Análise Espectral , Máquina de Vetores de Suporte
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