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1.
Biosci Biotechnol Biochem ; 84(1): 17-24, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31566084

RESUMO

Human milk oligosaccharides (HMOs) have drawn attention for their contribution to the explosive bifidobacterial growth in the intestines of neonates. We found that bifidobacteria can efficiently metabolize lacto-N-biose I (LNB), the major building blocks of HMOs, and we have developed a method to synthesize LNB by applying this system. We produced LNB on a kilogram scale by the method. This proved that, among the enterobacteria, only bifidobacteria can assimilate LNB, and provided the data that supported the explosive growth of bifidobacteria in neonates. Furthermore, we were also able to reveal the structure of LNB crystal and the low stability for heating at neutral pH, which has not been clarified so far. In this paper, using bifidobacteria and LNB as examples, I describe the research on oligosaccharide synthesis that was conducted by utilizing a sugar metabolism.Abbreviations: LNB: lacto-N-biose I; GNB: galacto-N-biose; HMOs: human milk oligosaccharides; GLNBP: GNB/LNB phosphorylase; NahK: N-acetylhexosamine 1-kinase; GalT: UDP-glucose-hexose-1-phosphate uridylyltransferase; GalE: UDP-glucose 4-epimerase; SP: sucrose phosphorylase.


Assuntos
Acetilglucosamina/análogos & derivados , Bifidobacterium/metabolismo , Glucosiltransferases/química , Leite Humano/química , Oligossacarídeos/metabolismo , Sacarose/química , Acetilglucosamina/síntese química , Acetilglucosamina/química , Acetilglucosamina/metabolismo , Resinas de Troca de Ânions/química , Bifidobacterium/crescimento & desenvolvimento , Cristalização , Dissacaridases/metabolismo , Microbioma Gastrointestinal/fisiologia , Temperatura Alta , Humanos , Concentração de Íons de Hidrogênio , Recém-Nascido
2.
Chemosphere ; 238: 124583, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31425865

RESUMO

The presence of bromide (Br-) in water results in the formation of brominated disinfection byproducts (DBPs) after chlorination, which are much more cytotoxic and genotoxic than their chlorinated analogs. Given that conventional water treatment processes (e.g., coagulation, flocculation, and sedimentation) fail to remove Br- effectively, in this study, we systematically tested and compared the performance of different anion exchange resins, particularly two novel Br-selective resins, for the removal of Br-. The resins performance was evaluated under both typical and challenging background water conditions by varying the concentrations of anions and organic matter. The overall Br- removal results followed the trend of Purolite-Br ≥ MIEX-Br > IRA910 ≥ IRA900 > MIEX-Gold > MIEX-DOC. Further evaluation of Purolite-Br resin showed Br- removal efficiencies of 93.5 ±â€¯4.5% for the initial Br- concentration of 0.25 mg/L in the presence of competing anions (i.e., Cl-, NO3-, NO2-, SO42-, PO43-, and a mixture of all five), alkalinity and organic matter. In addition, experiments under challenging background water conditions confirmed the selectivity of the resins (i.e. Purolite-Br and MIEX-Br) in removing Br-, with SO42- and Cl- exhibiting the greatest influence upon the resin performance followed by NOM concentration, regardless of the NOM characteristic. After Br- removal, both the subsequent formation of brominated DBPs (trihalomethanes, haloacetic acids, and haloacetonitriles), and the total organic halogens (TOX), decreased by ∼90% under the uniform formation conditions. Overall, Br-selective resins represent a promising alternative for the efficient control of Br-DBPs in water treatment plants.


Assuntos
Resinas de Troca de Ânions/química , Brometos/análise , Trialometanos/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Desinfecção/métodos , Floculação , Halogenação , Troca Iônica
3.
Chemosphere ; 238: 124633, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31454747

RESUMO

Three different source waters were investigated using virgin and pre-used anion exchange resins, coagulation, and ion exchange combined with coagulation (IEX&Coagulation). The hydrophobicity, size distribution and charge of natural organic matter (NOM) were used to evaluate its removal. Dissolved organic carbon (DOC) removal by pre-used IEX resin was 67-79%. A consistent ratio of different hydrophobicity fractions was found in the removed DOC, while the proportion and quantity of the molecular weight fraction around 1 kDa was important in understanding the treatability of water. For pre-used resin, organic compounds were hypothesised to be restricted to easily accessible exchange sites. Comparatively, virgin resin achieved higher DOC removals (86-89%) as resin fouling was absent. Charge density and the proportion of the hydrophobic fraction were found to be important indicators for the specific disinfection byproduct formation potential (DBP-FP). Treatment of raw water with pre-used resin decreased the specific DBP-FP by between 2 and 43%, while the use of virgin resin resulted in a reduction of between 31 and 63%. The highest water quality was achieved when the combination of IEX and coagulation was used, reducing DOC and the specific DBP-FP well below that seen for either process alone.


Assuntos
Compostos Orgânicos/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Resinas de Troca de Ânions/química , Floculação , Interações Hidrofóbicas e Hidrofílicas , Troca Iônica
4.
Prep Biochem Biotechnol ; 49(10): 1020-1032, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31407965

RESUMO

Proteolytic degradation is a serious problem that complicates downstream processing during production of recombinant therapeutic proteins. It can lead to decreased product yield, diminished biological activity, and suboptimal product quality. Proteolytic degradation or protein truncation is observed in various expression hosts and is mostly attributed to the activity of proteases released by host cells. Since these clipped proteins can impact pharmacokinetics and immunogenicity in addition to potency, they need to be appropriately controlled to ensure consistency of product quality and patient safety. A chromatography step for the selective removal of clipped proteins from an intact protein was developed in this study. Poly(ethylenimine)-grafted anion- exchange resins (PolyQUAT and PolyPEI) were evaluated and compared to traditional macroporous anion-exchange and tentacled anion-exchange resins. Isocratic retention experiments were conducted to determine the retention factors (k') and charge factors (Z) were determined through the classical stoichiometric displacement model. High selectivity in separation of closely related clipped proteins was obtained with the PolyQUAT resin. A robust design space was established for the PolyQUAT chromatography through Design-Of-Experiments (DoE) based process optimization. Results showed a product recovery of up to 63% with purity levels >99.0%. Approximately, one-log clearance of host cell protein and two-logs clearance of host cell DNA were also obtained. The newly developed PolyQUAT process was compared with an existing process and shown to be superior with respect to the number of process steps, process time, process yield, and product quality.


Assuntos
Resinas de Troca de Ânions/química , Cromatografia por Troca Iônica/métodos , Polietilenoimina/química , Proteínas/isolamento & purificação , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
5.
Anal Chim Acta ; 1079: 220-229, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31387715

RESUMO

We developed temperature-responsive mixed-mode columns packed with poly(N-isopropylacrylamide) (PNIPAAm)-modified beads and poly(2-acrylamido-2-methylpropane sulfonic acid) (PAMPS)-modified beads in various ratios. The PNIPAAm-modified silica beads and PAMPS-modified silica beads were prepared by surface-initiated atom transfer radical polymerization of N-isopropylacrylamide and 2-acrylamido-2-methylpropane sulfonic acid, respectively. We confirmed polymer modification of the silica beads by CHN elemental analysis, FTIR, zeta-potential measurements, and SEM. To determine the column separation efficiency, we examined the elution behaviors of cold medicine active ingredients and monoamines from each column. Analyte separation occurred on columns with PNIPAAm to PAMPS ratios of 1:20 and 1:10, whereas a column containing only PNIPAAm-modified beads did not retain the analytes. The analytes were retained on the columns through hydrophobic and electrostatic interactions with PNIPAAm and PAMPS, respectively. The separation performance improved with increasing column temperature because of dehydration of PNIPAAm and enhancement of hydrophobic interactions at elevated temperatures. The mixed-mode columns will be useful for separating basic bioactive compounds because the retention of analytes can be modulated by changing the column temperature and the composition.


Assuntos
Resinas Acrílicas/química , Resinas de Troca de Ânions/química , Cromatografia por Troca Iônica/instrumentação , Polímeros/química , Ácidos Sulfônicos/química , Alcaloides/análise , Aminas/análise , Cromatografia por Troca Iônica/métodos , Compostos Heterocíclicos de Anéis Fundidos/análise , Dióxido de Silício/química , Temperatura Ambiente
6.
Int J Mol Sci ; 20(14)2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31311111

RESUMO

To ameliorate the trade-off effect between ionic conductivity and water swelling of anion exchange membranes (AEMs), a crosslinked, hyperbranched membrane (C-HBM) combining the advantages of densely functionalization architecture and crosslinking structure was fabricated by the quaternization of the hyperbranched poly(4-vinylbenzyl chloride) (HB-PVBC) with a multiamine oligomer poly(N,N-Dimethylbenzylamine). The membrane displayed well-developed microphase separation morphology, as confirmed by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). Moreover, the corresponding high ionic conductivity, strongly depressed water swelling, high thermal stability, and acceptable alkaline stability were achieved. Of special note is the much higher ratio of hydroxide conductivity to water swelling (33.0) than that of most published side-chain type, block, and densely functionalized AEMs, implying its higher potential for application in fuel cells.


Assuntos
Resinas de Troca de Ânions/química , Fontes de Energia Elétrica , Membranas Artificiais , Álcalis/química , Benzilaminas/química , Reagentes para Ligações Cruzadas/química , Interações Hidrofóbicas e Hidrofílicas , Transporte de Íons , Polivinil/química
7.
Anal Bioanal Chem ; 411(14): 3103-3113, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30972471

RESUMO

13C metabolite tracer and metabolic flux analyses require upfront experimental planning and validation tools. Here, we present a validation scheme including a comparison of different LC methods that allow for customization of analytical strategies for tracer studies with regard to the targeted metabolites. As the measurement of significant changes in labeling patterns depends on the spectral accuracy, we investigate this aspect comprehensively for high-resolution orbitrap mass spectrometry combined with reversed-phase chromatography, hydrophilic interaction liquid chromatography, or anion-exchange chromatography. Moreover, we propose a quality control protocol based on (1) a metabolite containing selenium to assess the instrument performance and on (2) in vivo synthesized isotopically enriched Pichia pastoris to validate the accuracy of carbon isotopologue distributions (CIDs), in this case considering each isotopologue of a targeted metabolite panel. Finally, validation involved a thorough assessment of procedural blanks and matrix interferences. We compared the analytical figures of merit regarding CID determination for over 40 metabolites between the three methods. Excellent precisions of less than 1% and trueness bias as small as 0.01-1% were found for the majority of compounds, whereas the CID determination of a small fraction was affected by contaminants. For most compounds, changes of labeling pattern as low as 1% could be measured. Graphical abstract.


Assuntos
Isótopos de Carbono/análise , Cromatografia por Troca Iônica/métodos , Cromatografia de Fase Reversa/métodos , Espectrometria de Massas/métodos , Estudos de Validação como Assunto , Resinas de Troca de Ânions/química , Isótopos de Carbono/normas , Interações Hidrofóbicas e Hidrofílicas , Pichia/química , Padrões de Referência , Selênio/química
8.
Biotechnol J ; 14(8): e1800632, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-30945463

RESUMO

Protein A affinity chromatography is a core unit operation in antibody manufacturing. Nevertheless, there is not enough understanding of in-column antibody adsorption in the Protein A capture step. This work aims to investigate in situ the establishment of an antibody (trastuzumab) layer during Protein A chromatography both in terms of energetic contributions and uptake kinetics. Flow microcalorimetry is employed as a technique with an in situ operating detector, which provides an understanding of the thermodynamics of the adsorption process. In addition, the antibody uptake rate is also investigated in order to establish a correlation between its diffusion on the stationary phase and the associated thermodynamics. Two resins with different particle size, intraparticle porosity, and a Protein A ligand structure are studied: the synthetically engineered B-domain tetrameric MabSelect SuRe and the synthetically engineered C-domain hexameric TOYOPEARL AF-rProtein A HC. The uptake rate follows a pore diffusion model at low equilibrium time, showing a slower diffusivity after a certain time because of the heterogeneous binding nature of these two resins. In addition, the microcalorimetric studies show that adsorption enthalpy is highly favourable at low isotherm concentrations and evolves toward an equilibrium with increasing surface concentration. These data suggest that the relationship between adsorption enthalpy and the establishment of the antibody layer in the Protein A chain is consistent with heterogeneous adsorption.


Assuntos
Anticorpos/metabolismo , Proteína Estafilocócica A/metabolismo , Resinas de Troca de Ânions , Sítios de Ligação , Calorimetria , Cromatografia de Afinidade/métodos , Cinética , Ligantes , Trastuzumab/metabolismo
9.
J Chromatogr A ; 1597: 187-195, 2019 Jul 19.
Artigo em Inglês | MEDLINE | ID: mdl-30922722

RESUMO

Ion exchangers of high binding capacity and uptake rate are desired for high performance purification of proteins by ion exchange chromatography. For this purpose, we have herein developed a new anion exchanger by grafting N,N-Dimethylaminopropyl acrylamide (DMAPAA) onto Sepharose FF by atom transfer radical polymerization. Six DMAPAA-grafted Sepharose FF resins of the same grafting density but different chain lengths (ionic capacities, ICs) were prepared, and named as FF-pDMAPAAn (n denotes IC value, 65-831 mmol/L). Bovine serum albumin (BSA) adsorption and its chromatography were studied to evaluate the anion exchange resins. It was found that the equilibrium protein adsorption capacity (qm) increased rapidly from 91 mg/mL at IC = 65 mmol/L till reaching a peak value (368 mg/mL) at IC = 458 mmol/L and then decreased slightly with further increasing IC (chain length) to 831 mmol/L. The uptake rate, De/D0, defined as the ratio of effective diffusion coefficient (De) to free diffusivity of the protein (D0), also presented similar changes as a function of IC. Namely, De/D0 increased from 0.25 to 2.45 in the IC range of 65 to 458 mmol/L, kept almost unchanged from 458 to 573 mmol/L and then decreased slightly with further increase of IC to 831 mmol/L. Therefore, FF-pDMAPAA458 presented the best performance of the six resins for BSA adsorption, possessing very high qm and De/D0 values (368 mg/mL and 2.45, respectively). The resin was thus extensively characterized in the effect of ionic strength and column chromatography. The qm and De/D0 of FF-pDMAPAA458 were much higher than other anion exchangers reported in literatures and kept over 230 mg/mL and 2.3, respectively, at salt concentrations up to 100 mmol/L. Therefore, the dynamic binding capacity of the FF-pDMAPAA458 column was remarkably higher than Q Sepharose FF and other two typical polymer-grafted anion exchangers reported in literatures in the salt concentration range, and kept as high as 180-220 mg/mL in the superficial flow velocity rang of 150-1350 cm/h. Taken together, the results demonstrated that FF-pDMAPAA resins of appropriate ionic capacities are promising for high-performance protein chromatography.


Assuntos
Resinas de Troca de Ânions/química , Cromatografia por Troca Iônica/métodos , Proteínas/química , Sefarose/química , Acrilamida/química , Adsorção , Cromatografia por Troca Iônica/instrumentação , Íons/química , Cinética , Concentração Osmolar , Polietilenoimina/química , Soroalbumina Bovina/química
10.
J Chromatogr A ; 1596: 117-123, 2019 Jul 05.
Artigo em Inglês | MEDLINE | ID: mdl-30904170

RESUMO

Four covalently-bonded hyperbranched anion exchangers based on poly(styrene-divinylbenzene) (PS-DVB) substrate with different structure of the functional layer were prepared using mono- and dianionic amino acids such as glycine, ß-alanine, aspartic acid, and glutamic acid in the internal part of the functional layer. Selectivity of all anion exchangers toward weakly retained organic acids was investigated at different temperatures in order to evaluate the effect of the number of carboxylic groups in the functional layer and its hydrophilicity on the separation. It was found that dianionic amino acids used in the first modification cycle of hyperbranching provide the best resolution for mono- and divalent organic acids, which makes the number of carboxylic groups in the structure of amino acid a key factor in the separation of such analytes with covalently-bonded hyperbranched anion exchangers, while the role of amino acid hydrophilicity is not that significant. Stationary phases prepared using aspartic and glutamic acids provided baseline resolution for quinic, glycolic, acetic, lactic, formic, and galacturonic acids, which are not resolved to baseline with modern commercially available anion exchangers; the increase of temperature was found to be favorable for improving the resolution even further.


Assuntos
Aminoácidos Dicarboxílicos/química , Aminoácidos/química , Resinas de Troca de Ânions/química , Aminoácidos/isolamento & purificação , Cromatografia por Troca Iônica , Interações Hidrofóbicas e Hidrofílicas , Compostos Orgânicos/química , Poliestirenos/química , Temperatura Ambiente
11.
PLoS Negl Trop Dis ; 13(2): e0007051, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30817751

RESUMO

Human African trypanosomiasis (HAT), or sleeping sickness, is a neglected tropical disease that is fatal if untreated, caused by Trypanosoma brucei gambiense and T. brucei rhodesiense. In its 2012 roadmap, WHO targeted HAT for elimination as a public health problem in 2020 and for zero transmission in 2030. Diagnosis of HAT is a multistep procedure comprising of clinical suspicion, confirmation, and stage determination. Suspects are identified on clinical signs and/or on screening for specific antibodies. Parasitological confirmation of suspects remains mandatory to avoid unnecessary toxic drug administration. The positive predictive value of the antibody detection tests is low. Simple parasite detection techniques, microscopic examination of lymph node aspirate, or stained thick blood films lack sensitivity, whereas in T. brucei gambiense patients, the number of blood trypanosomes may be very low. Parasite concentration techniques are therefore indispensable. Half a century ago, Sheila Lanham discovered a technique to separate trypanosomes from the blood of infected rodents, based on anion exchange chromatography with diethyl amino ethyl (DEAE) cellulose, a weak anion exchanger. Between pH 6-9, trypanosome surface is less negatively charged than that of blood cells. When blood is poured on top of a DEAE cellulose column, blood cells are retained, whereas parasites pass the column together with the elution buffer. The result is a pure suspension of trypanosomes that retain their morphology and infectivity. Because cell surface charges vary among trypanosome and mammal species, the optimal buffer pH and ionic strength conditions for different combinations of host and trypanosome species were established. Lanham's technique revolutionized the diagnosis of HAT. It is indispensable in the production of the Card Agglutination Test for Trypanosomiasis (CATT), the most used field test for screening in T. brucei gambiense HAT foci and essential to confirm the diagnosis in suspected people. Lumsden and colleagues developed the mini anion exchange centrifugation technique (mAECT). After adaptation for field conditions, its superior diagnostic and analytical sensitivity compared to another concentration technique was demonstrated. It was recommended as the most sensitive test for demonstrating trypanosomes in human blood. At the beginning of the 21st century, the mAECT was redesigned, allowing examination of a larger volume of blood, up to 0.35 ml with whole blood and up to 10 ml with buffy coat. The plastic collector tube in the new kit is also used for detection of trypanosomes in the cerebrospinal fluid. Unfortunately, mAECT also has some disadvantages, including its price, the need to centrifuge the collector tube, and the fact that it is manufactured on a noncommercial basis at only two research institutes. In conclusion, 50 years after Sheila Lanham's discovery, CATT and mAECT have become essential elements in the elimination of HAT.


Assuntos
Resinas de Troca de Ânions , Cromatografia/história , Cromatografia/métodos , Trypanosoma brucei gambiense , Trypanosoma brucei rhodesiense , Tripanossomíase Africana/diagnóstico , Animais , Antígenos de Protozoários/química , Cromatografia/instrumentação , História do Século XX , Humanos , Tripanossomíase Africana/parasitologia
12.
Chemosphere ; 223: 39-47, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30763914

RESUMO

In this paper, a series of mono-functional and bifunctional anion exchange resins with different kinds of trialkylammonium groups were synthesized and used for adsorption of nitrate from aqueous solution. The obtained resins were systematically characterized by scanning electron microscopy, Fourier transform infrared spectrometry and pore size distribution. Adsorptive behaviors and mechanisms were investigated by batch experiments. The nitrate could be preferentially adsorbed in the presence of chloride, sulfate and humic acid by longer-chain trialkylamine modified resins. Especially, the L20 resin with the triethylammonium functional group was demonstrated to possess high selectivity toward nitrate with the highest distribution coefficient among all tested resins. For both single and bi-solutes systems, the adsorption isotherm data could be well fitted with the Langmuir model, while the experimental kinetic data was well described by both pseudo first-order and second-order kinetic model. The L20 resin could be reused after many adsorption-desorption cycles with most of its virgin adsorption capacity for advanced wastewater treatment, indicating its great potential for the selective and efficient removal of nitrate from large amounts of municipal wastewater or surface water.


Assuntos
Resinas de Troca de Ânions/química , Nitratos/química , Águas Residuárias/química , Purificação da Água/métodos , Adsorção , Resinas de Troca de Ânions/síntese química , Cinética , Nitratos/isolamento & purificação , Porosidade , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação
13.
Environ Sci Pollut Res Int ; 26(33): 34233-34247, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-30617880

RESUMO

Removal and recovery of phosphorus (P) from sewage are essential for sustainable development of P resource. Based on the water quality determination of sludge dewatering filtrate from a wastewater treatment plant in Beijing, this study investigated the adsorption and regeneration characteristics of P by magnetic anion exchange resin (MAEX). The experiments showed that the P adsorption capacity of MAEX could reach a maximum of 2.74 mg/mL when initial P concentration was 25 mg/L and dosage of MAEX was 8 mL/L. The P adsorption on MAEX resin was suitable for large temperature range (283-323 K). However, the adsorption capacity was reduced in various degrees due to the interference of different anions (Br-, SO42-, Cl-, NO3-, HCO3-, CO32-) and organic compounds (bovine serum albumin, humic acid). Kinetics studies indicated that the P adsorption process followed the pseudo-second-order model. The MAEX resin had a rapid P adsorption rate and the P adsorption capacity at 30 min could reach 97.7-99.3% of qe. Increase of temperature was favorable to P adsorption on MAEX, and the adsorption isotherm data fitted to Langmuir model more than Freundlich model. Meanwhile, the thermodynamics parameters were calculated; it was shown that the adsorption process was an endothermic reaction. Desorption and regeneration experiments showed that NaHCO3 was a suitable regenerant, and the P adsorption capacity could reach 90.51% of the original capacity after 10 times of adsorption-desorption cycles; this indicated that MAEX resin has an excellent regeneration performance and thus has a very good application prospect of P removal and recovery. Fourier transform infrared spectroscopy (FTIR) analysis confirmed that ion exchange, charge attraction, and hydrogen bonding affected the removal of P by the MAEX resin. The vibrating sample magnetometer (VSM) analysis revealed that MAEX resin was a kind of soft magnetic materials with good magnetism.


Assuntos
Resinas de Troca de Ânions/química , Fósforo/análise , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análise , Adsorção , Ânions , Pequim , Substâncias Húmicas , Concentração de Íons de Hidrogênio , Troca Iônica , Cinética , Fenômenos Magnéticos , Magnetismo , Esgotos , Espectroscopia de Infravermelho com Transformada de Fourier , Temperatura Ambiente , Termodinâmica , Águas Residuárias
14.
J Chromatogr A ; 1589: 65-72, 2019 Mar 29.
Artigo em Inglês | MEDLINE | ID: mdl-30598288

RESUMO

Three covalently-bonded poly(styrene-divinylbenzene)-based (PS-DVB) hyperbranched anion exchangers prepared using primary amines with carboxylic, sulfonic or 2-hydroxyethyl substituents in the internal part of the functional layer were studied and compared for evaluating the effect of amines substituents on the chromatographic performance of the stationary phases. The hyperbranched coating was created on the surface of aminated PS-DVB substrate by repeating the modification cycles including alkylation with 1,4-butanediol diglycidyl ether (1,4-BDDGE) and amination with primary amine; glycine, taurine (2-aminoethanesulfonic acid) or ethanolamine were used in the first cycle, and 4 more cycles were conducted with methylamine (MA). The influence of the structure and type of primary amine used in the first cycle on the retention and selectivity toward inorganic anions, short-chain carboxylic acids, and polyphosphates was investigated using hydroxide eluent. The effect of temperature on the separation of organic acids was also studied for all stationary phases, which revealed the possibility to control and improve resolution for some pairs of analytes.


Assuntos
Ácidos/química , Aminas/química , Resinas de Troca de Ânions/química , Compostos Orgânicos/química , Aminação , Cromatografia por Troca Iônica , Temperatura Ambiente
15.
Anal Bioanal Chem ; 411(3): 765-776, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30467768

RESUMO

The isotopic composition of iron, zinc, copper, and cadmium (δ56Fe, δ66Zn, δ65Cu, and δ114Cd) are novel and promising tools to study the metabolism and homeostasis of trace metals in the human body. Serum δ65Cu has been proposed as a potential tool for diagnosis of cancer in liquid biopsy, and other metals may have similar utility. However, accurate analysis of trace metal isotopes is challenging because of the difficulties in purifying the metals from biological samples. Here we developed a simple and rapid method for sequential purification of Cu, Fe, Zn, and Cd from a single blood plasma sample. By using a combination of 11 M acetic acid and 4 M HCl in the first steps of column chemistry on AG-MP1 resin, we dramatically improve the separation of Cu from matrix elements compared to previous methods which use concentrated HCl alone. Our new method achieves full recovery of Cu, Fe, Zn, and Cd to prevent column-induced isotope fractionation effects, and effectively separates analytes from the matrix in order to reduce polyatomic interferences during isotope analysis. Our methods were verified by the analysis of isotope standards, a whole blood reference material, and a preliminary sample set including five plasma samples from healthy individuals and five plasma samples from cancer patients. This new method simplifies preparation of blood samples for metal isotope analysis, accelerating multi-isotope approaches to medical studies and contributing to our understanding of the cycling of Fe, Zn, Cu, and Cd in the human body. Graphical abstract ᅟ.


Assuntos
Cromatografia por Troca Iônica/métodos , Cobre/sangue , Cobre/isolamento & purificação , Isótopos/sangue , Isótopos/isolamento & purificação , Biópsia Líquida , Adsorção , Resinas de Troca de Ânions , Neoplasias da Mama/sangue , Neoplasias da Mama/patologia , Estudos de Casos e Controles , Fracionamento Químico , Cobre/normas , Feminino , Humanos , Isótopos/normas , Espectrometria de Massas/instrumentação , Espectrometria de Massas/métodos , Padrões de Referência , Solventes/química , Oligoelementos/sangue , Oligoelementos/isolamento & purificação
16.
J Chromatogr A ; 1585: 121-130, 2019 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-30503698

RESUMO

Complex adsorption kinetics behaviors of proteins in mixtures hampers chromatographic process development and complicates model-based prediction of separation. We investigated the adsorption characteristics of mixtures comprised of a larger protein (secretory immunoglobulins or thyroglobulin) and a smaller protein (serum albumin or green fluorescence protein) on the small-pore anion exchanger Q Sepharose FF. Confocal laser scanning microscopy measurements revealed that binding of the large protein was extremely slow and eventually stopped completely after the adsorption front penetrated just a few µm into the particle. Binding capacities after 24 h of incubation were nevertheless around 35 mg/mL of particle which is relatively high when considering that only a fraction of the particle was saturated, suggesting that locally-high bound protein concentrations are attained in a layer close to the particle surface. During mixture adsorption, the bound protein layer also significantly hindered diffusion of the smaller proteins into the particles resulting in about three times slower adsorption kinetics compared to single component adsorption. The combined effects of restricted diffusion and protein binding explain why flow-through purification of these mixtures with the small-pore resin Q Sepharose FF is effective under practical conditions. In this resin, diffusion of secretory immunoglobulins (or thyroglobulin) is restricted in the small pores so that despite their intrinsically greater affinity for the resin, much less binds compared to small proteins. Using the large-pore resin POROS 50 HQ results in faster transport, but also in more binding of secretory immunoglobulins (or thyroglobulin) compared to smaller protein impurities, preventing effective flow-through purification.


Assuntos
Resinas de Troca de Ânions/química , Proteínas/isolamento & purificação , Adsorção , Difusão , Cinética , Proteínas/química , Sefarose/química
17.
Anal Sci ; 35(3): 347-350, 2019 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-30344207

RESUMO

We propose the creation of reusable indicator-sorbed-solids, using anion-exchange resins or kaolin as supports, with the aim to reduce chemical use towards green analytical chemistry. Indicators (phenolphthalein, thymol blue and butterfly pea flower extract as a natural indicator) sorbed on a solid support, were employed in acid-base titration, in both homogenous aqueous and heterogenous aqueous organic phases. Applications of the developed techniques to some real samples, such as vinegar, colored fruit juice and vegetable oil, have been demonstrated.


Assuntos
Resinas de Troca de Ânions/química , Análise de Alimentos/métodos , Química Verde/métodos , Indicadores e Reagentes/química , Caulim/química , Titulometria/métodos , Ácido Acético/análise , Adsorção , Sucos de Frutas e Vegetais/análise , Óleos Vegetais/análise
18.
J Anim Sci ; 97(3): 1020-1026, 2019 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-30423121

RESUMO

Absorption of dietary lipids in the small intestine is dependent on the emulsification by bile acids (BA) and the formation of chylomicrons. Cholestyramine is a common drug used in humans-and potentially dogs-to treat BA malabsorption associated with chronic diarrhea. It is known to bind BA to form insoluble complexes, preventing their reabsorption and possibly proper emulsification and absorption of dietary fats. The objective of this study was to evaluate the effects of cholestyramine on 1) macronutrient apparent total tract digestibility (ATTD), and 2) fecal characteristics and metabolites of healthy adult dogs. We hypothesized that cholestyramine would decrease ATTD of fat and organic matter (OM), increase fecal dry matter (DM) content, and increase fecal output. Twelve healthy beagles (3.2 ± 0.8 yr; 10.4 ± 0.9 kg) were used in a randomized crossover design. All procedures were approved by the University of Illinois Institutional Animal Care and Use Committee before the study. The study included a baseline period and two 14-d experimental periods separated by a 14-d washout. All dogs were fed the same experimental diet, formulated to meet all nutrient needs recommended by AAFCO, throughout the study. Dogs were randomized into 2 groups [diet only (control) or diet + 11.4 g/d cholestyramine (8 g/d active ingredient)] in Period 1 and received the other treatment in Period 2. During the washout, all dogs were fed the diet only. Dogs were fed once daily (0800 h) to maintain BW. Total fecal output was collected during the last 4 d of each period for ATTD analysis. On day 14 of each of period, fresh fecal and blood samples were collected for metabolite analysis. Dogs fed cholestyramine had lower (P < 0.001) ATTD of DM, OM, energy, crude protein, and fat and lower (P < 0.01) fecal scores (firmer stools) than controls. Dogs fed cholestyramine had greater (P < 0.01) as-is and dry fecal output than controls. Dogs fed cholestyramine had lower (P < 0.05) fecal ammonia and phenol concentrations, but greater (P < 0.05) fecal indole, acetate, butyrate, and total short-chain fatty acid concentrations than controls. Fecal DM% and pH were greater (P < 0.01) in dogs fed cholestyramine. Our results indicate that cholestyramine, when given with a meal, is safe and well tolerated but significantly decreases nutrient digestibility and alters fecal characteristics. Future studies are required to explore the effects of cholestyramine on dogs with gastrointestinal disease.


Assuntos
Resinas de Troca de Ânions/farmacologia , Resina de Colestiramina/farmacologia , Digestão/efeitos dos fármacos , Cães/fisiologia , Trato Gastrointestinal/fisiologia , Absorção Intestinal/efeitos dos fármacos , Amônia , Ração Animal , Fenômenos Fisiológicos da Nutrição Animal , Animais , Resinas de Troca de Ânions/uso terapêutico , Butiratos , Resina de Colestiramina/uso terapêutico , Estudos Cross-Over , Dieta , Gorduras na Dieta , Ácidos Graxos Voláteis , Fezes/química , Trato Gastrointestinal/efeitos dos fármacos , Nutrientes , Distribuição Aleatória
19.
Sci Total Environ ; 655: 571-580, 2019 Mar 10.
Artigo em Inglês | MEDLINE | ID: mdl-30476837

RESUMO

Cyanobacterial blooms are becoming a serious challenge across the globe due to changing climate and rainfall patterns as a consequence of human activities. In the present study, the fundamental interactions involved during the removal of Microcystin-LR (MCLR), one of the most commonly occurring cyanobacterial toxins, were investigated by employing strongly basic anion exchange (IX) resins. Several factors including the stoichiometric coefficients, competitive fractions and solute affinities were determined under various concentrations of inorganic ions and natural organic matter. The results indicated that suphates were the most competitive fractions with high affinity (α (affinity coefficient) values ~ 9) followed by nitrates (α ~ 4.7) and NOM fractions (α ~ 4.5, p < 0.05). The Equivalent Background Concentration Mode (EBC), that arises from the Ideal Adsorption Solution Theory (IAST), indicated a competitive fraction of ~2 µeq/L NOM, which approximates to <10% of the initial NOM concentrations, indicating a small fraction of the NOM resulting in the competitive effect. Further, studies with natural surface waters indicated that the MCLR uptake could be modeled using the IAST-EBC model and the IX resin could simultaneously removal of >90% of NOM, inorganic ions and MCLR at resin dosages of 3.6 meq/L or higher.


Assuntos
Resinas de Troca de Ânions/química , Microcistinas/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Substâncias Húmicas/análise , Microcistinas/análise , Poluentes Químicos da Água/análise
20.
J Sci Food Agric ; 99(1): 117-123, 2019 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-29808577

RESUMO

BACKGROUND: Activated almonds are raw almonds that have been soaked in water for 12-24 h at room temperature, sometimes followed by a 24 h drying period at low temperature (50 ± 5 °C). This treatment is thought to enhance the nutrient bioavailability of almonds by degrading nutrient inhibitors, such as phytic acid or d-myo-inositol hexaphosphate (InsP6 ), through the release of phytase or passive diffusion of InsP6 into the soaking water. Over a wide pH range, InsP6 is a negatively charged compound that limits the absorption of essential nutrients by forming insoluble complexes with minerals such as iron and zinc. It is hypothesized that hydrating the seed during soaking triggers InsP6 degradation into lower myo-inositol phosphates with less binding capacity. RESULTS: Anion-exchange chromatography coupled with tandem mass spectrometry was used to quantify myo-inositol mono-, di-, tris-, tetra-, penta-, and hexaphosphates (InsP1-6 ) in raw pasteurized activated almonds. At least 24 h of soaking at ambient temperature was required to reduce InsP6 content from 14.71 to 14.01 µmol g-1 . CONCLUSIONS: The reduction in InsP6 is statistically significant (P < 0.05) after 24 h of activation, but only represents a 4.75% decrease from the unsoaked almonds. © 2018 Society of Chemical Industry.


Assuntos
Fosfatos de Inositol/análise , Nozes/química , Prunus dulcis/química , 6-Fitase/metabolismo , Resinas de Troca de Ânions/química , Cromatografia por Troca Iônica/instrumentação , Cromatografia por Troca Iônica/métodos , Manipulação de Alimentos , Fosfatos de Inositol/isolamento & purificação , Proteínas de Plantas/metabolismo , Prunus dulcis/enzimologia , Espectrometria de Massas em Tandem/métodos
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