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1.
Food Chem ; 309: 125732, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-31706676

RESUMO

Impacts of different pretreatment conditions and atmosphere on yield and oxidative stability of lipids from Pacific white shrimp (Litopenaeus vannamei) cephalothorax using ultrasonic assisted extraction (UAE) process were studied. Cephalothorax was subjected to vacuum-microwave (VM) heating prior to UAE using a mixture of isopropanol/n-hexane (1:1) as solvent. Nitrogen gas was flushed at two flow rates; low (2.15 l/min) and high (4.35 l/min) into the system during ultrasonication. Vacuum-microwave heating resulted in the increase of lipid yield and highest yield was observed in the samples extracted by a combination of VM and UAE. Tannic acid (TA) was incorporated into cephalothorax at three different levels (0.05, 0.1 and 0.2%) in combination with VM, followed by nitrogen flushing. Nitrogen flushing during ultrasonication process resulted in the increased oxidative stability of lipids as confirmed by low PV, TBARS and FFA. Furthermore, astaxanthin content in the lipid was found to be increased by aforementioned treatments.


Assuntos
Lipídeos/química , Penaeidae/metabolismo , Sonicação , 2-Propanol/química , Animais , Atmosfera , Ácidos Graxos/análise , Hexanos/química , Lipídeos/isolamento & purificação , Micro-Ondas , Oxirredução , Solventes/química , Taninos/química , Vácuo , Xantofilas/análise
2.
Food Chem ; 302: 125334, 2020 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-31419773

RESUMO

Carotenoids, natural pigments, are a group of chemically heterogeneous molecules, present in numerous taxonomical clusters. Because of their various bioactivities, carotenoids are day-by-day applied in numerous fields. The present work aimed to investigate an efficient extraction process of carotenoids from blue crab shells and their identification by HR-ESI-MS technique. In this context, different methods (enzymatic, maceration, Soxhlet, etc.) and solvents (variable polarity index) were tested. Maceration using the binary system hexane/isopropanol (50/50) was found to be the most efficient process, producing high carotenoids content and low total phenolic and soluble protein amounts (p < 0.05). When combined with an enzymatic pretreatment, this procedure was found to be remarkably (p < 0.05) more efficient and selective especially towards astaxanthin (p < 0.05). The HR-ESI-MS identified 23 compounds, depending on the adopted extraction approach. The compounds identified may have potential for applications in food or pharmaceutical industries.


Assuntos
Exoesqueleto/química , Braquiúros/química , Carotenoides/isolamento & purificação , Fracionamento Químico/métodos , 2-Propanol/química , Animais , Carotenoides/análise , Hexanos/química , Fenóis/análise , Fenóis/química , Proteínas/análise , Proteínas/isolamento & purificação , Solventes/química , Espectrometria de Massas por Ionização por Electrospray , Espectroscopia de Infravermelho com Transformada de Fourier , Xantofilas/análise , Xantofilas/isolamento & purificação
3.
Molecules ; 24(16)2019 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-31409035

RESUMO

There have been developments in the optimization of polyether sulfone (PES) membranes, to provide antifouling and mechanically stable surfaces which are vital to water purification applications. There is a variety of approaches to prepare nanocomposite PES membranes. However, an optimized condition for making such membranes is in high demand. Using experimental design and statistical analysis (one-half fractional factorial design), this study investigates the effect of different parameters featured in the fabrication of membranes, as well as on the performance of a nanocomposite PES/TiO2 membrane. The optimized parameters obtained in this study are: exposure time of 60 s, immersion time above 10 h, glycerol time of 4 h, and a nonsolvent volumetric ratio (isopropanol/water) of 30/70 for PES and dimethylacetamide (PES-DMAc) membrane and 70/30 for PES and N-methyl-2-pyrrolidone (PES-NMP) membrane. A comparison of the contributory factors for different templating agents along with a nanocomposite membrane control, revealed that F127 triblock copolymer resulted in an excellent antifouling membrane with a higher bovine serum albumin rejection and flux recovery of 83.33%.


Assuntos
Nanocompostos/química , Polímeros/química , Sulfonas/química , Titânio/química , 2-Propanol/química , Acetamidas/química , Análise Fatorial , Glicerol/química , Humanos , Membranas Artificiais , Nanocompostos/ultraestrutura , Pirrolidinonas/química , Soroalbumina Bovina/química , Água/química , Purificação da Água/métodos
4.
Nanotechnology ; 30(49): 495501, 2019 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-31443101

RESUMO

With the capability of inducing small particle sizes of supported metal in graphite oxide (GO), the γ-ray irradiation method applied for preparing graphite oxide-gold (GO-Au) nanocomposites as electrochemical immunosensors has attracted specific attention recently. To study the accurate factors influencing the precise morphology and final performance of the prepared composites in the γ-irradiation system, we proposed a facile method to investigate the evolution of the GO structure, size and dispersion of Au nanoparticles (AuNPs) produced with the addition of isopropyl alcohol to the system. The GO-Au nanocomposites were characterized by Fourier transform infrared spectroscopy, x-ray diffraction spectra, Raman spectra, x-ray photoelectron spectroscopy and high resolution transmission electron microscopy. These nanocomposites with sandwich morphology exhibited an excellent immunosensor performance with a low detection limit of 15.8 pg ml-1 (S/N = 3) and a wide linear range from 1 to 40 ng ml-1 for detecting carcinoembryonic antigens. The enhanced biosensing performance is attributed to the synergistic effect of γ-irradiation and the precise structure of GO, which endows the smaller size and more uniform distribution of AuNPs on the GO as well as the good signal amplification capability. Furthermore, adopting the γ-irradiation method and use of GO as a precursor is propitious for application in large-scale production because of its high-efficiency and high-yielding characteristics.


Assuntos
Técnicas Biossensoriais , Antígeno Carcinoembrionário/sangue , Ouro/química , Imunoensaio , Nanopartículas Metálicas/química , Nanocompostos/química , 2-Propanol/química , Anticorpos Imobilizados/química , Técnicas Eletroquímicas , Raios gama , Grafite/química , Humanos , Limite de Detecção , Nanopartículas Metálicas/efeitos da radiação , Nanopartículas Metálicas/ultraestrutura , Nanocompostos/efeitos da radiação , Nanocompostos/ultraestrutura , Óxidos/química
5.
Int J Pharm ; 569: 118520, 2019 Oct 05.
Artigo em Inglês | MEDLINE | ID: mdl-31362093

RESUMO

The objective of this study was to investigate the applicability of water-insoluble polymers as binders for pellet drug layering to extend the drug release. Carbamazepine was layered on sugar cores in fluidized bed coater using isopropanol (IPA):water solution or aqueous dispersion of ethylcellulose, polyvinyl acetate or ammonium-methylmethacrylate copolymer. Carbamazepine release was extended with all investigated water-insoluble polymers used as binder, without an additional coating layer. Drug release from pellets layered using IPA:water polymer solutions was dependent on polymer properties such as lipophilicity and pore-forming components, while from those layered with aqueous polymer dispersions, the release was dependent on the completeness of film formation during drug layering. Curing effect was observed only for pellets layered with Aquacoat® ECD and Eudragit® RS 30D. The drug release was not affected by compression when pellets were prepared with the flexible polymers Kollidon® SR or Kollicoat® SR 30D, however, it increased when brittle polymers such as ethylcellulose or Eudragit® RS were used. This problem could be minimized by using a higher amount of the binder, addition of a plasticizer or using polymers of higher viscosity grade. In conclusion, the use of water-insoluble polymers as binder for pellet drug layering is an effective tool to extend the drug release without additional coating step.


Assuntos
Celulose/análogos & derivados , Composição de Medicamentos/métodos , Ácidos Polimetacrílicos/química , Polivinil/química , 2-Propanol/química , Carbamazepina/química , Celulose/química , Liberação Controlada de Fármacos , Excipientes/química , Solubilidade , Água/química
6.
J Chromatogr A ; 1603: 297-310, 2019 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-31227363

RESUMO

Surface modification of porous glass beads by ethanol-based 3-mercaptopropyltrimethoxysilane (MPTMS) grafting solutions is directly evidenced by nitrogen adsorption, elemental analysis, thermogravimetry, infrared and 29Si CP MAS NMR spectroscopy. Furthermore, the energetic characterization of the surface is essential to understand comprehensively the physico-chemical interactions between the pristine and MPTMS-modified surface and its gas/liquid-phase environment. In this study, inverse gas chromatography (IGC) is used to characterize the surface properties of porous glass (PG). By means of IGC at infinite dilution (IGC-ID), the dispersive component of the surface energy (γsd), the enthalpy and entropy of adsorption of C6-C10 hydrocarbon probes were determined at temperatures between 30 and 120 °C. The specific component of the surface energy (γssp) at the temperature of 120 °C has been obtained via the Van Oss theory and a least-squares procedure evaluating the IGC data of 8 polar probe molecules collectively. After surface silylation, the total surface energy (γst) decreased from 402 to 255 mJ/m² indicating both a reduced wettability and an increased hydrophobicity of the MPTMS-modified PG. Moreover, the acidity/basicity parameters according to the Van Oss and the Gutmann approach indicated that the acidity of the PG surface decreases by MPTMS grafting. Using n-octane and isopropanol probes, IGC at finite concentration (IGC-FC) was applied to obtain their adsorption isotherms and subsequently the BET specific surface areas. In addition, the surface heterogeneity of the studied PGs was also computed. The energy distribution functions of adsorption sites were monomodal (peak maximum at about 22 kJ/mol) for the n-octane probe, while isopropanol revealed a bimodal distribution function (maxima at about 18 and 25 kJ/mol) on both pristine and MPTMS-modified PG. Furthermore, the proportion of high energy sites (apparently assigned to SiOH groups) has been reduced by surface modification from 65% to only 35% despite a high surface coverage of ˜10 MPTMS species/nm2. These findings are in agreement with the results of 29Si CP MAS NMR measurements and are supported by DFT calculations on the adsorption of isopropanol and n-octane on the surface of a silica cluster model.


Assuntos
Cromatografia Gasosa/métodos , Dióxido de Silício/química , 2-Propanol/química , Ácidos/química , Adsorção , Alcanos/química , Teoria da Densidade Funcional , Entropia , Espectroscopia de Ressonância Magnética , Conformação Molecular , Nitrogênio/química , Porosidade , Silanos/química , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Temperatura Ambiente , Termogravimetria
7.
J Pharm Biomed Anal ; 173: 62-67, 2019 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-31121455

RESUMO

Measurement of peptides such as oxytocin in plasma is a critical challenge in clinical research because of their extreme low concentrations as well as the tremendous interferencing substances co-presented in plasma. In this study, we developed an efficient salt-out assisted liquid-liquid extraction (SALLE) to treat plasma, and then analyzed the samples using nano-LC-MS to quantify intact oxytocin (OT) in human and rat plasmas. Our results showed that the use of SALLE (Isopropanol/K2HPO4 (4 M)) allows efficient removal of various disrupters, including proteins, inorganic salts, and lipids, which helps avoid the risk of blocked capillary columns and matrix effects. Moreover, instant SALLE can reduce the possible binding between OT and proteins, thus allowing high repeatability of OT extraction from the original plasma. This combination of SALLE and nano-LC-MS method provided in the end a 1 pg/m L of detection limit. Comparative analysis showed that the concentration of OT in the plasma taken from 12 volunteers ranged from 3 to 214 pg/m L, about one order less than those in the plasma of rats. Compared to the previously reported LC-MS and immunoassay methods, the combination of SALLE and nano-LC-MS permits reliable measurement of intact OT even in human plasma. Our approach may be an alternative method for quantitative determination of other ultra-trace peptides in plasma, which would help the investigators understand the role of peptides in behaviours and diseases.


Assuntos
Extração Líquido-Líquido/métodos , Ocitocina/sangue , 2-Propanol/química , Animais , Cromatografia Líquida/métodos , Feminino , Voluntários Saudáveis , Humanos , Limite de Detecção , Masculino , Ocitocina/isolamento & purificação , Fosfatos/química , Compostos de Potássio/química , Ratos , Espectrometria de Massas em Tandem/métodos
8.
Environ Sci Pollut Res Int ; 26(20): 20908-20919, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31115812

RESUMO

Large amount of volatile organic compounds (VOCs) are emitted from industrial, mobile, and domestic sources, causing adverse effects on human health and environment. Among VOCs, toluene and isopropanol (IPA) are commonly used as solvent, soldering flux, and spray paint and their emissions need to be reduced. Several VOCs abatement technologies are available to reduce VOC emission and photocatalytic oxidation of VOC is regarded as a viable technique due to its advantage of utilizing solar energy. TiO2 has been investigated for its oxidation capability toward VOCs because of its good photocatalytic activity. However the utilization is limited to UV due to its wider bandgap; furthermore, its fast recombination rate of electron-hole pair reduces the oxidation rate of VOCs. Black-TiO2 and perovskite-type photocatalyst such as LaFeO3 can be applied to enhance photocatalytic activity due to narrower bandgap and longer electron-hole pair lifetime. In this study, black-TiO2 and LaFeO3 are prepared and investigated for their photocatalytic oxidation rates toward toluene and IPA. Results show that toluene removals achieved with black-TiO2 and LaFeO3 are 89% and 98% while IPA removals are 90% and 94%, respectively. Both photocatalysts show better photocatalytic activity than TiO2 and good absorption capability toward visible light. Graphical abstract.


Assuntos
2-Propanol/química , Poluentes Atmosféricos/química , Compostos de Cálcio/química , Óxidos/química , Titânio/química , Tolueno/química , 2-Propanol/isolamento & purificação , Poluentes Atmosféricos/isolamento & purificação , Catálise , Recuperação e Remediação Ambiental , Luz , Oxirredução , Processos Fotoquímicos , Tolueno/isolamento & purificação
10.
Drug Dev Ind Pharm ; 45(8): 1258-1264, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30995878

RESUMO

Gemfibrozil (GEM) is cholesterol-lowering agent which is being proposed as poorly water soluble drug (PWSD). Temperature based solubility values of GEM are not yet available in literature or any pharmacopoeia/monograph. Hence, the present studies were carried out to determine the solubility of PWSD GEM (as mole fraction) in various pharmaceutically used solvents such as water (H2O), methanol (MeOH), ethanol (EtOH), isopropanol (IPA), 1-butanol (1-BuOH), 2-butanol (2-BuOH), ethylene glycol (EG), propylene glycol (PG), polyethylene glycol-400 (PEG-400), ethyl acetate (EA), dimethyl sulfoxide (DMSO) and Transcutol® (THP) at the temperatures ranging from T = 298.2 K-318.2 K under atmospheric pressure P = 0.1 MPa. Equilibrium/experimental solubilities of GEM were recorded by applying a saturation shake flask methodology and regressed using 'van't Hoff and Apelblat models'. Hansen solubility parameters for GEM and various pharmaceutically used solvents were estimated using HSPiP software. The solid states of GEM (both in pure and equilibrated states) were studied by 'Differential Scanning Calorimetry' which confirmed no transformation of GEM after equilibrium. Experimental solubilities of GEM in mole fraction were observed maximum in THP (1.81 × 10-1) followed by DMSO, PEG-400, EA, 1-BuOH, 2-BuOH, IPA, EtOH, PG, MeOH, EG and H2O (3.24 × 10-6) at T = 318.2 K and similar tendencies were also recorded at T = 298.2 K, T = 303.2 K, T = 308.2 K and T = 313.2 K. 'Apparent thermodynamic analysis' on experimental solubilities furnished 'endothermic and entropy-driven dissolution' of GEM in each pharmaceutically used solvent.


Assuntos
Genfibrozila/química , Solubilidade/efeitos dos fármacos , Solventes/química , 2-Propanol/química , Acetatos/química , Etilenoglicóis/química , Metanol/química , Polietilenoglicóis/química , Temperatura Ambiente , Termodinâmica , Água/química
11.
Nanoscale ; 11(13): 6072-6079, 2019 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-30869704

RESUMO

A novel procedure for the preparation of magnetic covalent organic frameworks (COFs) is reported. In situ functionalization of Fe3O4 with dopamine rapidly afforded amino-functionalized magnetic nanoparticles, which after decoration with a COF building block and subsequent COF growth gave access to magnetic composite mTpBD-Me2. The optimized synthesis conditions yielded crystalline and superparamagnetic material with no loss in surface area as compared to bulk COF. The composite material was employed for the first time in magnetic solid-phase extraction of marine biotoxins from seawater with high efficiency, where calculated maximum adsorption capacities of 812 mg g-1 and 830 mg g-1 were found for okadaic acid (OA) and dinophysistoxin-1 (DTX-1), respectively, corresponding to an increase of ∼500-fold for OA and ∼300-fold for DTX-1 as compared to the commonly used non-magnetic macroporous resins. Nearly quantitative desorption efficiency of both biotoxins was obtained using 2-propanol as solvent, rendering the composite materials recyclable with merely minor losses in adsorption capacity after five consecutive cycles of adsorption/desorption. In addition, retention of crystallinity after the adsorption cycles highlights the stability of the composite in seawater. These results illustrate the great efficiency of the novel material in biotoxin adsorption and show great promise for its application in environmental monitoring programs.


Assuntos
Magnetismo , Estruturas Metalorgânicas/química , Ácido Okadáico/química , Piranos/química , 2-Propanol/química , Adsorção , Dopamina/química , Óxido Ferroso-Férrico/química , Cinética , Ácido Okadáico/isolamento & purificação , Piranos/isolamento & purificação , Extração em Fase Sólida
12.
PLoS Genet ; 15(3): e1008005, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30875383

RESUMO

Dipteran or "true" flies occupy nearly every terrestrial habitat, and have evolved to feed upon a wide variety of sources including fruit, pollen, decomposing animal matter, and even vertebrate blood. Here we analyze the molecular, genetic and cellular basis of odor response in the tsetse fly Glossina morsitans, which feeds on the blood of humans and their livestock, and is a vector of deadly trypanosomes. The G. morsitans antenna contains specialized subtypes of sensilla, some of which line a sensory pit not found in the fruit fly Drosophila. We characterize distinct patterns of G. morsitans Odor receptor (GmmOr) gene expression in the antenna. We devise a new version of the "empty neuron" heterologous expression system, and use it to functionally express several GmmOrs in a mutant olfactory receptor neuron (ORN) of Drosophila. GmmOr35 responds to 1-hexen-3-ol, an odorant found in human emanations, and also alpha-pinene, a compound produced by malarial parasites. Another receptor, GmmOr9, which is expressed in the sensory pit, responds to acetone, 2-butanone and 2-propanol. We confirm by electrophysiological recording that neurons of the sensory pit respond to these odorants. Acetone and 2-butanone are strong attractants long used in the field to trap tsetse. We find that 2-propanol is also an attractant for both G. morsitans and the related species G. fuscipes, a major vector of African sleeping sickness. The results identify 2-propanol as a candidate for an environmentally friendly and practical tsetse attractant. Taken together, this work characterizes the olfactory system of a highly distinct kind of fly, and it provides an approach to identifying new agents for controlling the fly and the devastating diseases that it carries.


Assuntos
Receptores Odorantes/genética , Atrativos Sexuais/genética , Olfato/genética , Tripanossomíase Africana/genética , 2-Propanol/química , Animais , Drosophila melanogaster/genética , Drosophila melanogaster/parasitologia , Humanos , Óleos/química , Neurônios Receptores Olfatórios/metabolismo , Neurônios Receptores Olfatórios/parasitologia , Atrativos Sexuais/química , Trypanosoma/genética , Trypanosoma/patogenicidade , Tripanossomíase Africana/parasitologia , Moscas Tsé-Tsé/genética , Moscas Tsé-Tsé/patogenicidade
13.
J Ind Microbiol Biotechnol ; 46(5): 675-685, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30706246

RESUMO

Propane is the main component of liquefied petroleum gas and is derived from crude oil processing. Methanotrophic bacteria can convert various alkanes using methane monooxygenase enzyme to primary alcohols. These are further oxidized to various aldehydes by alcohol dehydrogenases or methanol dehydrogenases. In this study, 2-propanol was produced from propane using the whole cells of Methylosinus trichosporium OB3b, Methylomicrobium alcaliphilum 20Z, and Methylomonas sp. DH-1 as the biocatalysts. The biocatalytic process of converting propane to 2-propanol was optimized by the use of several inhibitors and additives, such as EDTA, sodium phosphate, and sodium formate to prevent oxidation of 2-propanol to acetone and to enhance conversion of propane to propanol. The maximum titer of 2-propanol was 0.424 g/L, 0.311 g/L, and 0.610 g/L for Methylomonas sp. DH-1, M. alcaliphilum 20Z, and M. trichosporium OB3b whole cells, respectively. These results showed that type I and type II methanotrophs could be used as the potent biocatalyst for conversion of propane to propanol.


Assuntos
2-Propanol/química , Methylomonas/metabolismo , Methylosinus trichosporium/metabolismo , Propano/química , Acetona , Oxirredutases do Álcool/química , Álcoois , Alcanos , Catálise , Formiatos/química , Microbiologia Industrial , Methylococcaceae , Oxirredução , Oxigenases/química , Especificidade da Espécie
14.
Luminescence ; 34(2): 234-242, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30746869

RESUMO

The kinetics of the decomposition reaction of 4-(4,5-diphenyl-1H-imidazol-2-yl)phenyl acetate (1) in basic alcoholic media was investigated, using a simple fluorescence (FL) spectrophotometric procedure. The process was conveniently studied using FL, since the triphenylimidazole-derived ester 1 and its reaction products (the corresponding phenol 2 and phenolate 2- ) are all highly fluorescent (ΦFL  > 37%). By carefully selecting excitation and emission wavelengths, observed rate constants k1 in the order of 10-3 to 10-2  s-1 were obtained from either reactant consumption (λex  = 300 nm, λem  = 400 nm) or product formation (λex  = 350 nm, λem  = 475 nm); these were shown to be kinetically equivalent. Intensity-decay time profiles also gave a residual FL intensity parameter, shown to be associated to the distribution of produced species 2 and 2- , according to the basicity of the medium. Studying the reaction in both methanol (MeOH) and isopropanol (iPrOH), upon addition of HO- , provided evidence that the solvent's conjugate base is the active nucleophilic species. When different bases were used (tBuO- , HO- , DBU and TEA), bimolecular rate constants kbim ranging from 4.5 to 6.5 L mol-1  s-1 were obtained, which proved to be non-dependent on the base pKaH , suggesting specific base catalysis for the decomposition of 1 in alcoholic media.


Assuntos
Fluorescência , 2-Propanol/química , Catálise , Cinética , Metanol/química , Estrutura Molecular , Espectrometria de Fluorescência
15.
Int J Pharm ; 560: 394-405, 2019 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-30763682

RESUMO

The use of non-aqueous cellulose-based formulations for extrusion-spheronisation (E-S) is investigated. A 10 wt% hydroxypropyl cellulose/isopropyl alcohol solution (HPC/IPA) was identified as a suitable sticky liquid binder for preparing non-aqueous pastes. Preliminary tests were performed on a series of pastes using a ram as well as a laboratory roller screen extruder, since the former is commonly used in batch testing and the latter replicates the shear range in a manufacturing screen extruder. Pellets with acceptable size and shape distributions were obtained with Avicel® HFE-102 NF/HPC/IPA for ram E-S, and with Avicel® RC-591/HPC/IPA for screen E-S. Further investigation was performed with calcium carbonate added as a model active pharmaceutical ingredient. Both formulations were able to generate pellets with acceptable size and shape characteristics at up to 50 wt% carbonate loading: further work is required to optimise yields.


Assuntos
Carbonato de Cálcio/administração & dosagem , Química Farmacêutica/métodos , Excipientes/química , Tecnologia Farmacêutica/métodos , 2-Propanol/química , Carbonato de Cálcio/química , Celulose/análogos & derivados , Celulose/química , Composição de Medicamentos/métodos , Tamanho da Partícula
16.
Talanta ; 195: 619-627, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30625592

RESUMO

The cerebrospinal fluid (CSF) lipidome is attracting increasing attention due to the importance of lipids in brain molecular signaling and their involvement in several neurological diseases. Different solvent systems have been used for the extraction of multiple lipid classes from CSF but no comparative study of the effectiveness of these protocols has been carried out. To optimize CSF lipid extraction for lipidomic measurements by untargeted ultra-high performance liquid chromatography - mass spectrometry, we evaluate and compare two sample preparation protocols, one involving protein precipitation with isopropanol (IPA) and other consisting of a liquid-liquid extraction with chloroform-methanol. For that purpose, human CSF from neurologically healthy and normolipidemic volunteers was used. The criteria established to compare these two methods were based on four critical aspects of sample preparation: simplicity, lipid coverage, reproducibility and recovery efficiencies. We found that both methods were highly reproducible techniques (>75% of the lipids with coefficient of variation (CV) <30%). In terms of recovery, the single-step IPA procedure yielded better values for most of the lipid classes and it was less toxic and simpler than the liquid-liquid extraction method. In relation to lipid coverage, variation in selectivity was observed between methods, providing evidence that IPA was more selective for polar lipids. Overall, IPA precipitation provides excellent results in terms of simplicity of execution, lipid coverage, reproducibility and recovery. We conclude that it is a choice procedure for large-scale, untargeted lipid profiling using UHPLC-MS in CSF analysis.


Assuntos
2-Propanol/química , Lipídeos/líquido cefalorraquidiano , Solventes/química , Precipitação Química , Clorofórmio/química , Cromatografia Líquida de Alta Pressão , Humanos , Espectrometria de Massas , Metanol/química , Reprodutibilidade dos Testes
17.
Nanoscale ; 11(5): 2476-2483, 2019 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-30672548

RESUMO

Highly selective, fast detection of specific lung-cancer biomarkers (CMs) in exhaled human breath is vital to the development of enhanced sensing devices. Today, e-nose is a promising approach for the diagnosis of lung cancer. Nevertheless, considerable challenges to early-stage disease diagnostics still remain: e.g. decrease in sensor sensitivities in the presence of water vapor, sensor drift leading to the inability to calibrate exactly, relatively short sensor lifetimes, and difficulty discriminating between multiple diseases. However, there is a wide scope for breath diagnostics techniques, and all advanced electrodes applicable to e-nose devices will benefit them. Here, we present the promising sensing capabilities of bare multi-layer graphene (MLG) as a proof of concept for advanced e-nose devices and demonstrate its utility for biomolecule discrimination of the most common lung CMs (ethanol, isopropanol, and acetone). We report on a comparative study involving exposure of the three CM solutions on flat MLG (f-MLG) and patterned MLG (p-MLG) electrodes, where the electrical conductivity of p-MLG is significantly increased while applying acetone. Based on sensitivity tests, we demonstrate the ability to monitor the electrical response of graphene electrodes employing graphene of various wettabilities. Specifically, the f-MLG electrode displays almost 2 times higher sheet resistance (30 Ω sq-1) compared to the hydrophilic p-MLG (12 Ω sq-1). We show significant sensitivity to selected specific molecules of pristine f-MLG and p-MLG while applying CM solutions with a 1.4 × 105 ppm concentration. Finally, we show the selectivity of f-MLG and p-MLG-based sensors when exposed to 2.0 × 105 ppm solutions containing different CM combinations. Both sensors were selective in particular to acetone, since the presence of acetone leads to a sheet resistance increase. We demonstrate that an advanced e-nose approach integrated with MLG electrodes has significant potential as a design concept for utilization of molecular detection at variable concentrations such as in early-stage disease diagnosis. This early-stage approach will provide convenient and reusable complex monitoring of CMs compared to typical contact sensors which require target analysis and are limited by disposable measuring. Moreover, further integration of the Internet of Things will introduce advanced e-nose devices as a biotechnological innovation for disease resilience with the potential for commercialization.


Assuntos
Técnicas Biossensoriais/métodos , Testes Respiratórios/métodos , Nariz Eletrônico , Grafite/química , Neoplasias Pulmonares/diagnóstico , 2-Propanol/química , Acetona/química , Biomarcadores Tumorais/química , Calibragem , Condutividade Elétrica , Eletrodos , Etanol/química , Humanos , Óxidos/química , Oxigênio/química
18.
J Chromatogr A ; 1586: 52-61, 2019 Feb 08.
Artigo em Inglês | MEDLINE | ID: mdl-30595431

RESUMO

We report on a numerical and experimental study of the limits of peak refocusing and concentration enhancement that can be obtained with solvent front-assisted peak remobilization in a trap column receiving peaks eluting from a preceding analytical column. It is shown that the upper limit of peak refocusing can best be pursued by injecting a sufficiently large volume in a sufficiently narrow capillary and elute it with a sufficiently steep (ballistic) gradient. Corresponding equations offering a quantitative description have been derived and verified experimentally. For the latter purpose, peak volumes of the order of 0.5 to 2.0 µL were refocused in a dedicated set-up capable of trapping µL-sized peaks in a 75 µm i.d. capillary and remobilized using a nano-LC pump propelling an acetonitrile/isopropyl alcohol mixture with a viscosity matching that of the trapping solvent. Injecting 2.0 µL peaks, a peak refocusing factor of 17.3 could be achieved.


Assuntos
2-Propanol/química , Acetonitrilos/química , Butanos/análise , Cromatografia Líquida/métodos , Cetonas/análise , Limite de Detecção , Viscosidade
19.
Anal Chim Acta ; 1048: 66-74, 2019 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-30598159

RESUMO

In this study, two monophasic isopropanol-water mixtures (IPA:H2O 75:25 v/v and IPA:H2O 90:10 v/v) were compared with traditionally employed biphasic methods of Bligh & Dyer and Matyash et al. as extraction systems for lipidomics analysis in Hela cells. Samples were analyzed by UHPLC-ESI-QTOF-MS/MS in positive and negative mode using sequential window acquisition of all theoretical fragment ion spectra (SWATH) and a relatively new software (MS-DIAL) was employed for the processing of the data which includes detection of peaks, MS/MS spectra deconvolution, identification of detected lipids and alignment of peaks through the analyzed samples. The studied performance parameters such as precision, recoveries of isotopically labeled internal standards and endogenous lipids, number of extracted lipids, and complexity of employed procedure showed that extraction with IPA:H2O 90:10 v/v performs similar to the Matyash protocol and better than Bligh & Dyer as well as IPA:H2O 75:25 v/v. However, less complex monophasic protocol which is simpler to implement and can be executed in plastic rather than glass, make the monophasic IPA:H2O 90:10 v/v protocol an excellent alternative to the classical biphasic protocols for reversed phase LC-MS lipidomics studies.


Assuntos
Lipídeos/análise , Extração em Fase Sólida/métodos , 2-Propanol/química , Clorofórmio/química , Cromatografia Líquida de Alta Pressão/métodos , Células HeLa , Humanos , Metanol/química , Éteres Metílicos/química , Solventes/química , Espectrometria de Massas em Tandem , Água/química
20.
Bioresour Technol ; 276: 310-317, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30641329

RESUMO

The alcoholysis of Kraft lignin was catalyzed by bimetallic Ni-Cu supported on H-Beta, HZSM-5, MAS-7, MCM-41 and SAPO-11 zeolite materials in isopropanol solvent. Results showed that a higher bio-oil yield of 98.80 wt% and monomer yield of 50.83 wt% without obvious char were achieved at 330 °C for 3 h over Ni-Cu/H-Beta catalyst. Isopropanol was found to be more effective in H2 generation and facilitated to the hydrodeoxygenation of lignin-derived phenolic compounds. Moreover, the composition of liquid products was also influenced by the acidity and pore structure of catalyst. The superior cycloalkanes yield was produced over Ni-Cu/H-Beta with larger pore size and more acidity. In contrast, a large number of cyclic ketones/alcohols and alkanes were obtained over other zeolites supported catalysts with smaller pore size and less acid content. Besides, the temperature, time and solvent effect on the lignin depolymerization were also researched.


Assuntos
Cobre/química , Lignina/química , Níquel/química , Zeolitas/química , 2-Propanol/química , Álcoois/química , Alcanos/química , Catálise , Óleos Vegetais/química , Polimerização , Polifenóis/química , Porosidade , Solventes , Temperatura Ambiente
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