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1.
Anim Cells Syst (Seoul) ; 28(1): 161-170, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38686362

RESUMO

Sonic vibration (SV), or vibroacoustic therapy, is applied to enhance local and systemic blood circulation and alleviate pain using low-frequency sine wave vibrations. However, there is limited scientific data on the mechanisms through which the benefits are achieved. In this study, we investigated the impact of SV on inflammatory responses by assessing cytokine secretion in both in vivo and in vitro models. After inducing inflammatory responses in mice and macrophages, we studied cytokine expression and the symptoms of inflammatory diseases in response to three frequencies (14, 45, or 90 Hz) of SV stimulation at 0.5 m/s2 of amplitude. The results showed that SV at 90 Hz significantly increased interelukin-10 (IL-10) secretion in mice who were administered lipopolysaccharides (LPS) and increased the expression of IL-10 transcripts in peritoneal exudate cells and macrophages. Furthermore, SV at 90 Hz improved LPS-induced lethality and alleviated symptoms in a colitis model. In conclusion, this study scientifically proves the anti-inflammatory effects of vibration therapy through its ability to increase IL-10 expression.

2.
Mar Drugs ; 20(11)2022 Oct 29.
Artigo em Inglês | MEDLINE | ID: mdl-36355006

RESUMO

Dieckol, a phlorotannin from Ecklonia cava, has shown potential for use as an anticancer agent that selectively kills cancer cells. However, it is necessary to amplify its potency without damaging its inherent safety in order to develop it as a competitive chemotherapeutic. Here, we explored the controlled O-acylations of dieckol. Acyl groups could be consistently introduced to the 6-O position of dieckol with a high regioselectivity, which was confirmed by NOESY, HMBC and HSQC spectroscopies. In cytotoxicity studies on the newly synthesized 6-O-acetyl, 6-O-benzoyl dieckols and previously synthesized 6-O-alkyl dieckols against A549 vs. normal cells, all of the derivatives showed low cytotoxicity in normal cells with an IC50 of 481-719 µM, and highly structure-dependent cytotoxicity in A549 cells with an IC50 of 7.02 (acetyl)-842.26 (benzyl) µM. The selectivity index also showed a large structure dependency in the range of 0.67 (benzyl)-68.58 (acetyl). An analysis of the structure-activity relationship indicated that the activity was dramatically reduced in the presence of a benzene ring and was highly increased in the presence of small polar substituents. Conclusions: Controlled mono-O-modifications of dieckol could be a powerful tool to enhance the anticancer activity of dieckol, thus contributing to the development strategy for dieckol-based chemotherapeutics.


Assuntos
Benzofuranos , Carcinoma Pulmonar de Células não Pequenas , Neoplasias Pulmonares , Phaeophyceae , Humanos , Carcinoma Pulmonar de Células não Pequenas/tratamento farmacológico , Neoplasias Pulmonares/tratamento farmacológico , Benzofuranos/química , Phaeophyceae/química
3.
Soft Matter ; 18(46): 8885-8893, 2022 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-36377482

RESUMO

The ABA-type triblock-copolymers (BCPs) of polylactide (PLA) and poly(ethylene glycol) (PEG) were synthesized as axle components for rotaxane formation. It is known that α-cyclodextrin (CD) exists near the PEG moiety in pseudo-polyrotaxane (PPRX), and the PLA moiety can form a stereocomplex (SC), by mixing with L- and D-isomers. In this study, various CDs, including ß-CD and γ-CD, were used as wheel components, and effects of CD structures on both PPRX and SC formations were studied. The solubility of CDs is influenced to form the PPRX, resulting in differing numbers of CDs in the axle. PPRX structures were investigated by 1H NMR, NOESY, and DOSY, and SC structures were investigated by FT-IR and XRD. Their thermal properties were also evaluated by DSC and TGA, to consider the physical properties of the simultaneous formation of PPRX and SC. This study gave insight into the complicated host-guest and polymer-polymer interactions.


Assuntos
Ciclodextrinas , Rotaxanos , Rotaxanos/química , Polietilenoglicóis/química , Espectroscopia de Infravermelho com Transformada de Fourier , Poliésteres/química , Ciclodextrinas/química , Polímeros/química
4.
Food Chem ; 381: 132123, 2022 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-35134743

RESUMO

Clarifiers are substances used during the winemaking process to enhance clarity and stability in the wines. The different clarifiers may alter removal capacities differently. In this study, the removal efficiency of seven common fining agents, divided into three groups (mineral clarifiers, synthetic polymeric clarifiers, and vegetable protein clarifiers), was analyzed with Asymmetrical Flow Field-Flow fractionation (AF4). Besides, the relationship between the removal capacity and different molecular and macromolecular properties has been evaluated. The results showed extensive removal of colloidal and macromolecular matter by the bentonites with potential impact on characteristic properties of the wine. The vegetable clarifiers showed a more profiled reduction, potentially preserving characteristics of the wine. The synthetic polymers showed a more limited removal efficiency but with a high affinity to remove colloidal phenols. The use of AF4-UV-MALS-dRI allowed the characterization of the wines after different clarification treatments, showing to be an analytical technique with a potential impact on the wine industry.


Assuntos
Fracionamento por Campo e Fluxo , Vinho , Coloides , Fracionamento por Campo e Fluxo/métodos , Substâncias Macromoleculares , Fenóis , Vinho/análise
5.
Pharmaceutics ; 13(11)2021 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-34834267

RESUMO

The addition of glycerol to protein solutions is often used to hinder the aggregation and denaturation of proteins. However, it is not a generalised practice against chemical degradation reactions. The chemical degradation of proteins, such as deamidation and isomerisation, is an important deteriorative mechanism that leads to a loss of functionality of pharmaceutical proteins. Here, the influence of glycerol on the chemical degradation of a protein and its correlation to glycerol-induced conformational changes is presented. The time-dependent chemical degradation of a pharmaceutical protein, GA-Z, in the absence and presence of glycerol was investigated in a stability study. The effect of glycerol on protein conformation and oligomerisation was characterised using asymmetric field-flow fractionation and small-angle neutron scattering in a wide glycerol concentration range of 0-90% v/v. The results from the stability study were connected to the observed glycerol-induced conformational changes in the protein. A correlation between protein conformation and the protective effect of glycerol against the degradation reactions deamidation, isomerisation, and hydrolysis was found. The study reveals that glycerol induces conformational changes of the protein, which favour a more compact and chemically stable state. It is also shown that the conformation can be changed by other system properties, e.g., protein concentration, leading to increased chemical stability.

6.
J Chromatogr A ; 1658: 462591, 2021 Nov 22.
Artigo em Inglês | MEDLINE | ID: mdl-34656839

RESUMO

In this report, we put forward an experimental method to determine the ionic strength of an aqueous solution. To this end, we have developed a theory of ionic strength I expressed in terms of the retention ratios in field-flow fractionation (FFF) as I1/2=κ(1-R)/(1-Ro)-ε-1/2. Here R is a measured retention ratio using an FFF technique, for instance, sedimentation FFF (SdFFF), and Ro is the sterically-corrected standard retention ratio as given by the standard retention theory (SRT) for a latex particle system of diameter d. For a standard latex system with known d (or Ro) and I, we can construct a linear calibration of I1/2 against (1-R)/(1-Ro). Therefore, if we measure the retention ratio R of a carrier liquid of which ionic strength is of interest, then we will be able to estimate the ionic strength from the calibration curve thus built. In this paper, we have demonstrated the relation of I1/2with respect to (1-R)/(1-Ro) for the polystyrene latex systems of which information on R, Ro, and I is available from Ref. [1].


Assuntos
Fracionamento por Campo e Fluxo , Calibragem , Concentração Osmolar , Tamanho da Partícula , Água
7.
Anal Bioanal Chem ; 413(25): 6313-6320, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34415361

RESUMO

1-Ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) is widely used as a crosslinker for fluorescence labeling of protein in the fields of biochemistry and food analysis. Many natural polysaccharides often contain some proteins or peptides that are very low in content but play a vital role in their biological function as well as technical applications. Determination of these low-content proteinaceous matters requires a highly sensitive and selective method. In this study, a methodological approach for investigations of the presence of proteinaceous material over the molar mass distribution (MD) of polysaccharides was developed using gum acacia (GA) as a model polysaccharide. EDC fluorescence-labeling method was modified by changing the pH (7, 9, and 11) of the solution for the analysis of low-content protein in food materials. Fluorescence spectroscopy and asymmetrical flow field-flow fractionation (AF4) were employed for characterizing the labeling efficiency and physiochemical properties of unlabeled and fluorescence-labeled GA. AF4 provided molar mass (M) and the radius of gyration (rG) of arabinogalactan (AG) and arabinogalactan protein complex (AGP) and determined the presence of proteinaceous matter over the MD. The labeling efficiencies of GA at pH 7, 9, and 11 determined by fluorescence spectroscopy were 56.5, 68.4, and 72.0%, respectively, with an increment of 15.5% when pH was increased from 7 to 11. The modified EDC fluorescence-labeling method allows highly sensitive and selective analysis of low-content proteinaceous matters and their distribution in natural polysaccharides.


Assuntos
Fracionamento Químico/métodos , Etildimetilaminopropil Carbodi-Imida/química , Goma Arábica/química , Proteínas/química , Soroalbumina Bovina/química , Concentração de Íons de Hidrogênio , Sensibilidade e Especificidade
8.
J Agric Food Chem ; 68(49): 14564-14576, 2020 Dec 09.
Artigo em Inglês | MEDLINE | ID: mdl-33236630

RESUMO

The particle matter of wine is mainly composed of wine colloids and macromolecules. The present work develops a methodology using asymmetrical flow field-flow fractionation coupled with multi-angle light scattering, differential refractive index detector, and ultraviolet detector (AsFlFFF-MALS-dRI-UV) for the fractionation and determination of the molar mass, the hydrodynamic radius, and the apparent densities of the aggregates and macromolecules present in wine samples. The results from a set of six Argentinian high-altitude wines showed two main populations: the first population composed of wine colloids with higher UV-specific absorptivity and the second population composed of polysaccharides, such as arabinogalactans. The conformation results showed that population 1 consists of small and dense particles, while population 2 showed high molar masses and lower densities. The results demonstrated the use of AsFlFFF as a new, effective method for the fractionation and characterization of wine colloids and wine macromolecules in red wines with further potential applications.


Assuntos
Fracionamento por Campo e Fluxo/métodos , Nanopartículas/química , Vinho/análise , Coloides/isolamento & purificação , Fracionamento por Campo e Fluxo/instrumentação , Hidrodinâmica , Peso Molecular , Refratometria
9.
PLoS One ; 15(11): e0242605, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33232370

RESUMO

Protein-based drugs often require targeted drug delivery for optimal therapy. A successful strategy to increase the circulation time of the protein in the blood is to link the therapeutic protein with an albumin-binding domain. In this work, we characterized such a protein-based drug, GA-Z. Using asymmetrical flow field-flow fractionation coupled with multi-angle light scattering (AF4-MALS) we investigated the GA-Z monomer-dimer equilibrium as well as the molar binding ratio of GA-Z to HSA. Using small angle X-ray scattering, we studied the structure of GA-Z as well as the complex between GA-Z and HSA. The results show that GA-Z is predominantly dimeric in solution at pH 7 and that it binds to monomeric as well as dimeric HSA. Furthermore, GA-Z binds to HSA both as a monomer and a dimer, and thus, it can be expected to stay bound also upon dilution following injection in the blood stream. The results from SAXS and binding studies indicate that the GA-Z dimer is formed between two target domains (Z-domains). The results also indicate that the binding of GA-Z to HSA does not affect the ratio between HSA dimers and monomers, and that no higher order oligomers of the complex are seen other than those containing dimers of GA-Z and dimers of HSA.


Assuntos
Técnicas de Química Analítica/métodos , Proteínas Recombinantes de Fusão/metabolismo , Espalhamento a Baixo Ângulo , Albumina Sérica Humana/metabolismo , Cromatografia em Gel , Dimerização , Humanos , Modelos Moleculares , Peso Molecular , Ligação Proteica , Conformação Proteica
10.
J Chromatogr A ; 1633: 461625, 2020 Dec 06.
Artigo em Inglês | MEDLINE | ID: mdl-33128976

RESUMO

Electrical asymmetrical flow field-flow fractionation (EAF4) is an interesting new analytical technique that separates proteins based on size or molecular weight and simultaneously determines the electrical characteristics of each population. However, until now, the research using EAF4 has not been published except for the proof-of-concept in the original publication by Johann et. al. in 2015 [1]. Hence the methods capabilities and optimized conditions need to be further investigated, such as composition of the carrier liquid, pH stability and effect of the electric field strength. The pH instability was observed in the initial method of EAF4 due to the electrolysis products when applied electric field. Therefore, we have investigated and provided a modified method for rapid pH stabilization through additional focusing step with the electric field. Then, the electrical properties such as the zeta-potential and effective net charge of the monomer and oligomers of three different proteins (GA-Z, BSA, and Ferritin) were determined based on their electrophoretic mobility from EAF4. The results showed that there were limitations to the applicability of separation by EAF4 to proteins. Nevertheless, this study shows that EAF4 is an interesting new technique that can examine the zeta-potential of individual proteins in mixtures (or monomers and oligomers) not accessible by other techniques.


Assuntos
Técnicas de Química Analítica/métodos , Técnicas Eletroquímicas , Fracionamento por Campo e Fluxo , Proteínas/análise , Proteínas/isolamento & purificação , Técnicas de Química Analítica/instrumentação
11.
Analyst ; 144(15): 4559-4568, 2019 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-31225551

RESUMO

Asymmetric flow field-flow fractionation (AF4) is a separation technique in which a focusing/relaxation step is used after the sample is injected onto the separation channel. During the focusing/relaxation step, the sample is focused by two counter-directed flows. This allows sample components to establish a diffusion-dependent equilibrium concentration profile. The focusing step may, in some cases, cause a loss of sample due to adsorption into the accumulation wall (i.e. the membrane) or due to aggregation of the sample. In addition, the increase in sample concentration during the focusing step may prevent complete relaxation and cause overloading effects. In this study, a modified AF4 channel equipped with a frit inlet (FI-AF4) is utilized, where the sample is relaxed hydrodynamically as it enters to the channel through the frit. The main advantage of the FI-AF4 channel is to omit the focusing step. The FI-AF4 channel could also allow higher injection mass than in a conventional channel while still avoiding overloading. The purpose of the present study is to compare two channels (conventional and FI-AF4 channels) in terms of the plate height (H), resolution (Rs) and the mass recovery for analysis of a mixture of glycogen and pullulan. In addition, waxy maize (WM) starch was used to compare the mass overloading of the two channels. The results show that the type of relaxation method (i.e. focusing or hydrodynamic relaxation) had no significant effect on mass recovery. The resolution (Rs), was higher in the conventional AF4 channel than in the FI-AF4 channel for the separation of glycogen and pullulan. The results also show that it was possible to inject a higher mass of WM starch (i.e. twice the mass) onto the FI-AF4 channel, compared to a conventional AF4 channel, without observing an overloading effect.

12.
Anal Bioanal Chem ; 411(16): 3665-3674, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31069435

RESUMO

Starch is one of the main carbohydrates in food; it is formed by two polysaccharides: amylose and amylopectin. The granule size of starch varies with different botanical origins and ranges from less than 1 µm to more than 100 µm. Some physicochemical and functional properties vary with the size of the granule, which makes it of great interest to find an efficient and accurate size-based separation method. In this study, the full-feed depletion mode of split-flow thin cell fractionation (FFD-SF) was employed for a size-based fractionation of two types of starch granules (corn and potato) on a large scale. The fractionation efficiency (FE) of fraction-a for corn and potato granules was 98.4 and 99.4%, respectively. The FFD-SF fractions were analyzed using optical microscopy (OM) and gravitational field-flow fractionation (GrFFF). The respective size distribution results were in close agreement for the corn starch fractions, while they were slightly different for the potato starch fractions. The thermal properties of FFD-SF fractions were analyzed, and the results for the potato starch showed that the peak temperature of gelatinization (Tp) slightly decreases as the size of the granules increases. Additionally, the enthalpy of gelatinization (ΔH) increases when the granule size increases and shows negative correlation with the gelatinization range (ΔT).

13.
Carbohydr Polym ; 206: 21-28, 2019 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-30553314

RESUMO

Non-solvent precipitated starch (non-SPS) is a novel component for starch-based emulsions. Herein, three non-SPS materials were prepared using ethanol as a precipitant of waxy maize starch granules (WMs). The WMs were either untreated (SP) or pre-treated via acid-hydrolysis (AHSP). In addition, SP was modified using n-octenyl succinic anhydride (OSA), yielding OSASP. This study aimed to investigate the influence of the non-SPS preparation method on the size, molar mass (M), and apparent density (ρapp) of the materials when subjected to different dissolution/dispersion procedures using asymmetrical flow field-flow fractionation (AF4). The results showed that the molar mass, size, and apparent density depended on the type of non-SPS with a decrease in Mw (1.8-9.4 g/mol) and rrms (60-148 nm) upon re-dispersion in different media in the order: SP > OSASP > AHSP. Moreover, different types of non-SPS materials displayed different conformational properties and were stable in aqueous solution at room temperature in the investigated time (24 h).

14.
J Chromatogr A ; 1587: 189-196, 2019 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-30558845

RESUMO

A theoretical model is proposed to analyze the shape effect on the retention behaviors of rod-like particles in field-flow fractionation. This model is improved from a previous model for slender-body rods by Park and Mittal [Chromatography (2015) 2: 472-487]: The model can predict the retention behaviors of the rods, of which shape is assumed as a prolate ellipsoid, with low and high aspect ratios in various flow conditions of the flow-field flow fractionation. The effects of rod aspect ratio on the retention behaviors of the rods with the same volume are investigated in each operation mode. In normal mode, the retention ratio decreases with increasing aspect ratio. In steric-entropic mode, where we substantially improved the model to evaluate the rod orientation and the cross-sectional concentration distribution more rigorously based on our recent studies [Nanomaterials (2018) 8:130; Chem. Eng. Sci. (2018) 189:396-400], the retention ratio increases with the increasing aspect ratio. In steric mode, the retention ratio decreases with increasing aspect ratio again. Those results are discussed based on how the cross-sectional concentration distributions are affected by the aspect ratio. The new criteria for the prediction of each mode are also discussed and suggested Comparison with the experimental data shows the qualitative agreement.


Assuntos
Entropia , Fracionamento por Campo e Fluxo/métodos , Modelos Teóricos , Difusão
15.
Anal Bioanal Chem ; 410(20): 4867-4873, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29808297

RESUMO

The analysis of aggregates of therapeutic proteins is crucial in order to ensure efficacy and patient safety. Typically, the analysis is performed in the finished formulation to ensure that aggregates are not present. An important question is, however, what happens to therapeutic proteins, with regard to oligomerization and aggregation, after they have been administrated (i.e., in the blood). In this paper, the separation of whole blood, plasma, and serum is shown using asymmetric flow field-flow fractionation (AF4) with a minimum of sample pre-treatment. Furthermore, the analysis and size characterization of a fluorescent antibody in blood plasma using AF4 are demonstrated. The results show the suitability and strength of AF4 for blood analysis and open new important routes for the analysis and characterization of therapeutic proteins in the blood.


Assuntos
Anticorpos/sangue , Proteínas Sanguíneas/análise , Fracionamento por Campo e Fluxo/métodos , Anticorpos/análise , Humanos , Imunoglobulina G/análise , Imunoglobulina G/sangue , Agregados Proteicos , Multimerização Proteica , Espectrometria de Fluorescência
16.
J Chromatogr A ; 1556: 97-102, 2018 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-29731290

RESUMO

We propose a new analytical scheme in which field-flow fractionation (FFF)-based separation of target-specific polystyrene (PS) particle probes of different sizes are incorporated with amplified surface-enhanced Raman scattering (SERS) tagging for the simultaneous and sensitive detection of multiple microRNAs (miRNAs). For multiplexed detection, PS particles of three different diameters (15, 10, 5 µm) were used for the size-coding, and a probe single stranded DNA (ssDNA) complementary to a target miRNA was conjugated on an intended PS particle. After binding of a target miRNA on PS probe, polyadenylation reaction was executed to generate a long tail composed of adenine (A) serving as a binding site to thymine (T) conjugated Au nanoparticles (T-AuNPs) to increase SERS intensity. The three size-coded PS probes bound with T-AuNPs were then separated in a FFF channel. With the observation of extinction-based fractograms, separation of three size-coded PS probes was clearly confirmed, thereby enabling of measuring three miRNAs simultaneously. Raman intensities of FFF fractions collected at the peak maximum of 15, 10 and 5 µm PS probes varied fairy quantitatively with the change of miRNA concentrations, and the reproducibility of measurement was acceptable. The proposed method is potentially useful for simultaneous detection of multiple miRNAs with high sensitivity.


Assuntos
Sondas de DNA/química , Fracionamento por Campo e Fluxo/métodos , MicroRNAs/análise , Tamanho da Partícula , Poliestirenos/química , Análise Espectral Raman/métodos , DNA de Cadeia Simples/química , Estudos de Viabilidade , Ouro/química , Nanopartículas/química , Reprodutibilidade dos Testes
17.
Anal Bioanal Chem ; 410(2): 451-458, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-29167934

RESUMO

In this work, asymmetrical flow field-flow fractionation (AF4) coupled with UV/Vis, multi-angle light scattering (MALS), and differential refractive index (dRI) detectors (AF4-UV-MALS-dRI) was employed for analysis of glutamate decarboxylase (LbGadB) from Lactobacillus brevis (L. brevis). AF4 provided molecular weight (MW) (or size)-based separation of dimer, hexamer, and aggregates of LbGadB. The effect of pH on oligomerization of LbGadB was investigated, and then AF4 results were compared to those from molecular modeling. The MWs measured by AF4-UV-MALS-dRI for dimeric and hexameric forms of LbGadB were 110 and 350 kDa, respectively, which are in good agreements with those theoretically calculated (110 and 330 kDa). The molecular sizes determined by AF4-UV-MALS-dRI were also in good agreement with those obtained from molecular modeling (6 and 10 nm, respectively, for dimeric and hexameric from AF4-UV-MALS-dRI and 6.4 × 7.6 and 7.6 × 13.1 nm from molecular modeling). The effects of temperature, salt type, and salt concentration on oligomerization of LbGadB were also investigated using dynamic light scattering (DLS). It was found that the hexameric form of LbGadB was most stable at pH 6 and in presence of NaCl or KCl. The results indicate that AF4, in combination of various online detectors mentioned above, provides an effective tool for monitoring of oligomerization of LbGadB under different conditions, such as temperature, pH, type of salts, and salt concentrations.


Assuntos
Glutamato Descarboxilase/química , Levilactobacillus brevis/enzimologia , Difusão Dinâmica da Luz , Estabilidade Enzimática , Fracionamento por Campo e Fluxo , Concentração de Íons de Hidrogênio , Levilactobacillus brevis/química , Modelos Moleculares , Multimerização Proteica , Refratometria , Sais/química , Temperatura
18.
J Chromatogr A ; 1528: 75-82, 2017 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-29126589

RESUMO

We investigate an explicit role of the ionic strength in the retention behaviors of polystyrene (PS) latex particles in sedimentation field-flow fractionation (SdFFF) by hinging upon the retention theory recently developed [1] asR=(Ro+vb*)/(1+vb*). Here R is an experimental retention ratio, and Ro is the analytical expression of the standard retention theory based on the parabolic flow velocity. The reduced boundary velocityvb* is expressed in terms of the ionic strength I of the carrier liquid as vb*=vb,o*/(1+εI), where vb,o*=0.070and ε=60 mM-1 for all the PS latex systems under investigation. We then apply this to study the explicit ionic strength effect on the retention behaviors of PS beads of 200, 300, 400, and 500nm, respectively. As a primary result, the strong dependence of the retention ratio on the ionic strength can be quantitatively accounted for in an excellent accuracy: The slip effect at the channel surface is significant, particularly when I≲0.5mM, without showing any distinguishable dependence on the specific additives to control I, such as FL-70, SDS, NaNO3, and NaN3. Based on the present study, we put forward an experimental means to estimate the ionic strength of an aqueous solution using an FFF technique.


Assuntos
Fracionamento por Campo e Fluxo , Modelos Químicos , Concentração Osmolar , Poliestirenos/química , Água/química
19.
Anal Bioanal Chem ; 409(19): 4551-4558, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28508088

RESUMO

The macromolecular composition of beer is largely determined by the brewing and the mashing process. It is known that the physico-chemical properties of proteinaceous and polysaccharide molecules are closely related to the mechanism of foam stability. Three types of "American pale ale" style beer were prepared using different mashing protocols. The foam stability of the beers was assessed using the Derek Rudin standard method. Asymmetric flow field-flow fractionation (AF4) in combination with ultraviolet (UV), multiangle light scattering (MALS) and differential refractive index (dRI) detectors was used to separate the macromolecules present in the beers and the molar mass (M) and molar mass distributions (MD) were determined. Macromolecular components were identified by enzymatic treatments with ß-glucanase and proteinase K. The MD of ß-glucan ranged from 106 to 108 g/mol. In addition, correlation between the beer's composition and foam stability was investigated (increased concentration of protein and ß-glucan was associated with increased foam stability).


Assuntos
Cerveja , Fracionamento por Campo e Fluxo/métodos , Peso Molecular
20.
Food Res Int ; 94: 13-19, 2017 04.
Artigo em Inglês | MEDLINE | ID: mdl-28290362

RESUMO

In this work, the ability of asymmetrical flow field-flow fractionation (AF4) coupled with UV-vis, multiangle light scattering (MALS), and quasi-elastic light scattering (QELS) (AF4-UV-MALS-QELS) for monitoring aggregation of components of egg yolk plasma was evaluated. The effect of external factors (i.e., pH, storage conditions, freezing and heat treatments) on the egg yolk plasma was studied. The results reveal that the aggregation mechanism of components of egg yolk plasma during heat and freezing treatment is different. The results suggest that the low density lipoproteins (LDLs) in egg yolk plasma undergo a 'clusters-fusion-gel' process under heat treatment at pH10. The alkaline conditions promote the formation of LDL aggregates. Also, storage conditions play a role in the formation of LDL aggregates. It was found that the hen eggs stored for 7days at room temperature contain less aggregate than those stored at 4°C for the same period. The combination of AF4 with online MALS-QELS provided conformational information in terms of the shape and size distribution of LDL aggregates. AF4-UV-MALS-QELS was proved to be a rapid and gentle method for the separation and characterization of egg yolk plasma aggregates.


Assuntos
Gema de Ovo/química , Armazenamento de Alimentos/métodos , Fracionamento por Campo e Fluxo/métodos , Luz , Lipoproteínas LDL/química , Temperatura , Animais , Galinhas , Difusão Dinâmica da Luz , Congelamento , Temperatura Alta , Humanos , Concentração de Íons de Hidrogênio , Plasma , Raios Ultravioleta
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