Relevant bibliographies by topics / Electrophoretic exclusion

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  1. Journal articles
  2. Dissertations / Theses
  3. Books
  4. Book chapters
  5. Conference papers

Academic literature on the topic 'Electrophoretic exclusion'

Author: Grafiati
Published: 4 June 2021
Last updated: 1 February 2022

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Journal articles on the topic "Electrophoretic exclusion"

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Kenyon, Stacy M., Michael W. Keebaugh, and Mark A. Hayes. "Development of the resolution theory for electrophoretic exclusion." ELECTROPHORESIS 35, no. 18 (July 21, 2014): 2551–59. http://dx.doi.org/10.1002/elps.201300572.

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Meighan, Michelle M., Michael W. Keebaugh, Alicia M. Quihuis, Stacy M. Kenyon, and Mark A. Hayes. "Electrophoretic exclusion for the selective transport of small molecules." ELECTROPHORESIS 30, no. 21 (November 2009): 3786–92. http://dx.doi.org/10.1002/elps.200900340.

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Esplandiu, Maria J., David Reguera, and Jordi Fraxedas. "Electrophoretic origin of long-range repulsion of colloids near water/Nafion interfaces." Soft Matter 16, no. 15 (2020): 3717–26. http://dx.doi.org/10.1039/d0sm00170h.

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Zhu, Fanyi, Brent L. Nannenga, and Mark A. Hayes. "Electrophoretic exclusion microscale sample preparation for cryo-EM structural determination of proteins." Biomicrofluidics 13, no. 5 (September 2019): 054112. http://dx.doi.org/10.1063/1.5124311.

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Meighan, Michelle M., Jared Vasquez, Luke Dziubcynski, Sarah Hews, and Mark A. Hayes. "Investigation of Electrophoretic Exclusion Method for the Concentration and Differentiation of Proteins." Analytical Chemistry 83, no. 1 (January 2011): 368–73. http://dx.doi.org/10.1021/ac1025495.

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Kenyon, Stacy M., Noah G. Weiss, and Mark A. Hayes. "Using electrophoretic exclusion to manipulate small molecules and particles on a microdevice." ELECTROPHORESIS 33, no. 8 (April 2012): 1227–35. http://dx.doi.org/10.1002/elps.201100622.

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Zhu, Fanyi, and Mark A. Hayes. "Simulation and experiment of asymmetric electrode placement for electrophoretic exclusion in a microdevice." ELECTROPHORESIS 40, no. 2 (November 6, 2018): 304–14. http://dx.doi.org/10.1002/elps.201700497.

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Kazmierczak, S. C., F. Van Lente, A. M. McHugh, and W. E. Katzin. "Macroamylasemia with a markedly increased amylase clearance ratio in a patient with renal cell carcinoma." Clinical Chemistry 34, no. 2 (February 1, 1988): 435–38. http://dx.doi.org/10.1093/clinchem/34.2.435.

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Abstract We report hyperamylasemia, macroamylasemia, and a markedly increased amylase clearance/creatinine clearance ratio in a patient with renal cell carcinoma. Serum amylase activity was characterized as macroamylase by gel exclusion chromatography. Electrophoretic separation revealed an atypical band of amylase, migrating anodal to the S2 control fraction. Electrophoresis of urine revealed the presence of both S1 and S2 fractions, but not the atypical band found in serum. Quantification of the salivary- and pancreatic-type amylase fractions showed amylase in urine to be 100% salivary. Immunofixation disclosed the macroamylase to consist of an immune complex between amylase and IgA-lambda antibody. Binding-capacity studies showed that the serum immunoglobulin was present in excess and could bind 46% and 49% additional S-type amylase activity derived from saliva and the patient's urine, respectively. The amylase clearance/creatinine clearance ratio was markedly supranormal (0.134), unexpected in a patient with macroamylasemia. A biopsy specimen of the renal cell tumor was found to contain significant salivary-type amylase activity. These results suggest production of amylase by tumor tissue in the renal carcinoma and secretion of S-type amylase into the patient's urine. Evidently, macroamylase should be confirmed by gel exclusion chromatography.
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Duggleby, Ronald G. "Calculation of the molecular weight of proteins from electrophoretic and gel exclusion chromatographic experiments." Bioinformatics 10, no. 2 (1994): 133–35. http://dx.doi.org/10.1093/bioinformatics/10.2.133.

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Sherwood, J. D., and S. Ghosal. "Nonlinear electrophoresis of a tightly fitting sphere in a cylindrical tube." Journal of Fluid Mechanics 843 (March 28, 2018): 847–71. http://dx.doi.org/10.1017/jfm.2018.212.

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We investigate electrophoresis of a tightly fitting sphere of radius $R-h_{0}$ on the axis of a circular tube of radius $R$, using lubrication theory and ideas due to Schnitzer & Yariv (Phys. Fluids, vol. 26, 2014, 122002). The electrical charge clouds on both the cylindrical wall and the surface of the sphere are assumed thin compared to the gap between the sphere and cylinder, so that charge clouds do not overlap and ion exclusion effects are minimal. Nevertheless, non-uniform pumping of counter-ions within the charge clouds leads to a change in the ionic concentration outside the charge clouds in the narrow gap between sphere and cylinder. The electro-osmotic slip velocities at the two surfaces are modified, leading to a decrease in the electrophoretic velocity of the sphere at low Péclet numbers and an increase in the velocity at high Péclet numbers. When the field strength $E_{0}$ is low, it is known that the electrophoretic velocity $U_{0}$ is proportional to $E_{0}(\unicode[STIX]{x1D701}_{s}-\unicode[STIX]{x1D701}_{c})$ which is zero when the zeta potential $\unicode[STIX]{x1D701}_{s}$ on the sphere surface is equal to the zeta potential $\unicode[STIX]{x1D701}_{c}$ on the cylinder. The perturbation to the above low field strength electrophoretic velocity (at high Péclet number) is predicted to be proportional to $E_{0}^{3}(\unicode[STIX]{x1D701}_{s}+\unicode[STIX]{x1D701}_{c})^{2}(\unicode[STIX]{x1D70E}_{s}+\unicode[STIX]{x1D70E}_{c})$, where $\unicode[STIX]{x1D70E}_{s}$ and $\unicode[STIX]{x1D70E}_{c}$ are the surface charge densities on the sphere and cylinder. The choice of materials with similar or identical zeta potentials (and surface charge densities) for the cylinder and sphere should therefore facilitate the observation of velocities nonlinear in the field strength $E_{0}$, since the reference linear electrophoretic velocity will be small.
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Dissertations / Theses on the topic "Electrophoretic exclusion"

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Sjöholm, Elisabeth. "Characterisation of kraft pulps by size-exclusion chromatography and kraft lignin samples by capillary zone electrophoresis." Doctoral thesis, KTH, Pulp and Paper Technology, 1999. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2846.

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In the present thesis two analytical methods forcharacterisation of underivatised pulp and lignin samplesobtained from kraft pulping of hardwood and softwood areevaluated. The first method is the use of lithiumchloride/N,N-dimethylacetamide (LiCl/DMAc) for dissolution andsize-exclusion chromatography (SEC) of pulps. The applicabilityof LiCl/DMAc-SEC is demonstrated for birch wood kraft pulpswith different relations between zero-span tensile strength andviscosity. The second method concerns the applicability ofcapillary zone electrophoresis (CZE) for characterising blackliquor and isolated lignin samples with respect to mobility,i.echarge density. A method for determining the averagemobility (µav) of the mobility distributions to easecomparison between samples is also presented.

The solubility in LiCl/DMAc and the elution behaviour in SECdiffer between hardwood and softwood kraft pulps. Hardwoodkraft pulps are completely dissolved in LiCl/DMAc, whereas highamounts of lignin and presence of glucomannan restrict thesolubility of softwood kraft pulps. The undissolved fraction ofsoftwood kraft pulps consists of larger amounts of mannose andlignin but has a diminished xylose content compared with theinitial pulp. Xylan and cellulose of hardwood kraft pulps arefairly well separated by LiCl/DMAc-SEC. In contrast, themolecular weight distributions (MWD) of softwood kraft pulpsare more complex. It was found that the hemicelluloses ofsoftwood pulps elute over the entire molecular weight range,indicating various degrees of association with cellulose. Theneutral monosaccharide composition implies that associationsbetween galactoglucomannan and cellulose increase withdecreasing amount of galactose. The elution behaviour ofsoftwood kraft pulp xylan suggests that this xylan consist ofsubstructures with varying propensity for associating withcellulose and/or mannan. In absence of associations betweencellulose and hemicellulose, cellulosic solutions of LiCl/DMAcconsist of cellulose aggregates, which is seen as a shoulder onthe high molecular weight end of the MWD of cellulose.According to the profiles of the MWD and light scatteringmeasurements, it is possible to break these aggregates bymechanical treatment of the solutions, without causing severecleavage of the glycosidic bonds. The relation between MWD andzero-span tensile strength was studied on hardwood kraft pulpsdegraded by gamma irradiation, oxygen/alkali or alkali. For alltreatments, the MWD of cellulose is shifted to a lowermolecular weight range as degradation proceeds. In thechemically treated pulps, a shoulder on the lowmolecular-weight end of the cellulose distribution graduallydevelops, which is not seen for the gamma treated pulps. Theobserved decrease in shape factor/fibre strength of thechemically treated-pulps is proposed to be due to a combinationof heterogeneous degradation and removal of hemicellulosewhereas the decrease in Mw of cellulose is of minorimportance.

The mobility distributions obtained by CZE differ betweenblack liquor, isolated dissolved lignin and isolated residuallignin. The µav measured at pH 12 reveals that theresidual lignin isolated from pine wood kraft pulp has asignificantly lower charge density than the lignin removed fromthe pulp throughout the cook. At the end of the kraft cook ofbirch, the µav of the isolated residual lignin is aboutthe same as that of the isolated dissolved lignin, whichsuggests that the solubility is sufficient for the pulp ligninto be dissolved. Comparisons between the µav at pH 12 andpH 10 indicate that the isolated dissolved lignin samplesobtained in the middle of the cook have a lower acidity thanthe other samples. The observed difference in µav betweenblack liquor and isolated dissolved lignin may be due toassociations between lignin fragments and carbohydrate polymersin the black liquor.

Keywords:Kraft pulps, Black liquor, Cellulose,Hemicellulose, Lignin, LiCl/DMAc, Dimethylacetamide,Size-exclusion chromatography, Capillary zoneelectrophoresis

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Fasciano, Jennifer Marie. "Use of Surfactant Modifiers for High-Performance Liquid Chromatography of Aliphatic and Aromatic Acids and Capillary Electrophoresis of Glycosaminoglycans." Miami University / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=miami1448126648.

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Haider, Syed. "Enhanced gel electrophoresis (GE) and inductively coupled plasma-mass spectrometry (ICP-MS) based methods for the identification and separation of proteins and peptides." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/10279.

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The main focus of the PhD study was to develop new gel electrophoresis and ICP-MS based methods to analyze a wide variety of the bio-molecules such as proteins, phosphoproteins and metalloproteins etc. The tricine-sodium dodecyl sulfate-polyacrylamide gel electrophoresis (tricine-SDS-PAGE) method is commonly used to resolve low molecular mass proteins, however, it requires a high percentage gel and a very complicated procedure to achieve this separation. This study describes a modification to tricine-SDS-PAGE to make it more effective for the separation of smaller proteins and for coupling to ICP-MS. The modified method employs low percentage PAGE gels and low reagent concentrations that provide efficient separations, good quantitation and low matrix levels that are compatible with ICP-MS. This modified method was applied to analyze phosphopeptides. Phosphopeptides are very small in size and difficult to separate using the other techniques such as Laemmli SDS-PAGE, original tricine-SDS-PAGE, immobilized metal affinity chromatography (IMAC), size exclusion chromatography (SEC) etc. In this study a simplified procedure is described based on modifying the original tricine-SDS-PAGE method. A comparative study showed that this modified method successfully resolved a digest mixture of very low to high molecular mass phosphopeptides/peptides. In off-line coupling of this method with ICP-MS, much better recoveries of the peptides from the gel were obtained as compared to traditional methods which indicate the compatibility of this modified method for quantitative studies. An on-line coupling of the modified system with ICP-MS was also demonstrated and it was applied for the separation, detection and quantification of phosphopeptides. Another application of this modified system was the separation of serum proteins. Blood serum contains five major protein groups i.e., albumin, alpha-1 globulin, alpha-2 globulin, beta globulin and gamma globulin. The separation of these five major proteins in a single gel is difficult to achieve using traditional methods. The modified system was shown to be superior for the separation of these serum proteins in a 7% (m/v) native-PAGE gel and a cellulose acetate membrane. A further study was carried out into controlling the factors that cause metal loss and protein fragmentation in SDS-PAGE. Using a reducing sample buffer, and heating to high temperatures (90-100ºC) in alkaline or acidic conditions may cause protein fragmentation and decrease the metal binding affinity. 70ºC was found suitable to prepare the sample at neutral, alkaline or acidic pH as no fragmentation observed. To prevent metal loss, the binding constant (log K) values of metal-amino acids, play the major role. Those metals which have high binding affinities with the amino acids in proteins can also be affected by the variation of the pH so prior information about pH to maintain the binding constant values is essential to minimize metal loss. This was observed in the loss of zinc, and to a lesser extent copper from human serum albumin (HSA) as measured by inductively coupled plasma mass spectrometry (ICP-MS). The method described above was applied for the separation and quantification of the serum proteins obtained from age-related macular degeneration (AMD) patients (where the AMD patients were from Moorfields Eye Hospital, London). Zn and Cu were quantified employing external calibration. Zn concentration showed variation whilst Cu did not show any significant variations in samples from AMD patients. A brief study of the interaction of cisplatin and oxaliplatin with HSA and transferrin was also performed. Cisplatin bound much faster than oxaliplatin with HSA. After 24 hours incubation, cisplatin showed a decrease in signal intensity which indicates that cisplatin binding decreases with time. Cisplatin binding with transferrin as compared to HSA was not significant, which could be the result of unstable Pt-transferrin complex formation. Oxaliplatin did not show high binding to either protein, perhaps due to the presence of the bulky, non polar DACH ligand.
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Le, Minh Thang. "Approches analytiques pour l'analyse et la caractérisation d'anticorps thérapeutiques dégradés : intérêt de la spectrométrie de masse en mode non-dénaturant." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS567.

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La manipulation des anticorps monoclonaux thérapeutiques (Acm) reconstitués avant administration aux patients est susceptible d’entraîner leurs dégradations physiques (e.g. dénaturation, agrégation). Ceci peut avoir un impact sur leur efficacité et sécurité. Afin d’étudier la conformation et la stabilité des Acms reconstitués, nous avons développé des méthodes séparatives couplées avec la spectrométrie de masse (MS) en conditions non-dénaturantes (« native »). Une méthode de CZE-native MS utilisant un revêtement constitué d’une triple-couche ionique a été développée pour séparer et détecter les différentes conformations (monomère natifs, dénaturés, dimères) d’Infliximab. Une étude approfondie réalisée en analysant de l’infliximab digéré a permis d’établir que la formation du dimère était liée à la dénaturation du fragment Fab. L’intérêt des revêtements statiques (commerciaux et préparés in situ) ont été étudiés pour analyser les Acms par CZE-UV et CZE-MS. Nos résultats ont montré l’intérêt d’un nouveau revêtement monolithique. Un couplage simultané de la SEC avec la MS et un détecteur de fluorescence a été développé. Nous avons ainsi identifié les conditions expérimentales qui entraînaient des dénaturations et des dimérisations artificielles. Cette méthode a ensuite été également appliquée avec succès pour la caractérisation d’un échantillon de Trastuzumab stressé. Une méthode orthogonale en utilisant la SEC-mobilité ionique-MS a été employé pour évaluer la proportion de monomères dénaturés par rapport aux monomères natifs. La méthodologie ainsi développée permettra la détection de très faibles taux d'anticorps dégradés dans des poches d'infusion. Ceci permettra de définir les paramètres critiques à maîtriser lors de la reconstitution et la manipulation d’anticorps à usage hospitalier
Manufacturing and manipulation of therapeutic monoclonal antibodies (mAb) in the hospital before administration to patient is prone to induce their physical degradations (e.g., denaturation, aggregation). This may impact their efficacy and safety. To study the stability of mAbs, capillary zone electrophoresis (CZE) and size exclusion chromatography (SEC), coupled to native mass spectrometry (MS) have been developed. CZE-native MS method using a triple-layer coating was developed to detect and separate different conformational states (unfolded monomer, dimer) of Infliximab in a single analysis. In-depth study with digested infliximab confirmed that dimer formation was related to the Fab fragment. We also focused on covalent coatings in order to find the more adapted coating to analyze mAbs by CZE-UV and CZE-MS. We also developed for SEC a simultaneous coupling with MS and a fluorescence detector to detect the degraded mAbs. We have identified the biases inducing conformational changes (e.g. dimerization, denaturation) that may arise during native MS. We also successfully characterized aggregates and denatured monomer in stressed Trastuzumab sample. In addition, the orthogonal method SEC-ion mobility-MS has been employed to separate and measure the denatured monomers compared to their related native conformations. Moreover, the developed system enables the detection of a very low levels of degraded mAbs in infusion bags. It allows to define the critical parameters to be controlled during the reconstitution and manipulation of therapeutic mAbs in hospital
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Maldaner, Fernanda Pavani Stamm. "Avaliação da potência do hormônio da paratireóide humano recombinante por bioensaio, métodos cromatográficos e eletroforético." Universidade Federal de Santa Maria, 2017. http://repositorio.ufsm.br/handle/1/13313.

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Fundação de Amparo à Pesquisa do Estado do Rio Grande do Sul - FAPERGS
The human parathyroid hormone (hPTH) is a polypeptide secreted by the parathyroid glands that is essential for the maintenance of the calcium ion homeostasis in the blood. The recombinant DNA technology has enabled the expression of hPTH gene in Escherichia coli, and thus the large-scale production of recombinant human parathyroid hormone (rhPTH 1-34), teriparatide, which contain the active amino-terminal fragment of the full length hPTH. The rhPTH is clinically used to treat osteoporosis at high risk of fractures in postmenopausal women, men with osteoporosis primary or hypogonadal and adults with glucocorticoid-induced osteoporosis (GIO). Cappilary zone electrophoresis (CZE) method was developed and validated for the assessment of rhPTH in biopharmaceutical formulations. The analysis for CZE method was performed on a fused-silica capillary (effective length, 40 cm; 50 μm i.d.), using electrolyte solution consisted of 50 mM dihydrogen phosphate solution at pH 3.0. The capillary was maintained at 25º C, the applied voltage was 20 kV. Injections were performed using a pressure mode at 50 mbar for 45 s, with detection by photodiode array detector set at 200 nm. Separation was obtained with a migration time of 5.3 min, and was linear over the concentration range of 0.25-250 μg mL-1 (r2 = 0.9992). The limits of detection and quantitation were 0.12 and 0.40 μg/mL, respectively. Specificity and stability-indicating capability were established in degradation studies, which also showed that there was no interference of the excipients. The accuracy was 100.28% with bias lower than 0.85%. Moreover, the in vitro cytotoxicity test of acidic, photolytic and thermal degradated forms showed significant differences (p<0.05) compared to intact molecule. The cell proliferation and alkaline phosphatase activity bioassays in UMR-106 cells were developed and applied to assess the biological activity of rhPTH in biopharmaceutical formulations The results of content/potency were correlated to those of the validated reversed-phase liquid chromatography (RP-LC), size-exclusion liquid chromatography (SE-LC) and CZE methods, showing significant correlation (p> 0.05) Thus, the application of the validated physico-chemical methods together with in vitro bioassays, was suggested to improve quality control of rhPTH biotechnology-derived product and to support studies of biosimilars.
O hormônio da paratireóide humano (hPTH) é um polipeptídeo produzido e secretado pelas glândulas paratireóides, e é fundamental para a manutenção da homeostase dos íons cálcio no sangue. A tecnologia do DNA recombinante possibilitou a expressão do gene do hPTH em Escherichia coli, e a produção em grande escala do hormônio da paratireóide humano recombinante (rhPTH 1-34), também denominado Teriparatida, o qual apresenta a sequência de aminoácidos responsável pela porção biologicamente ativa do paratôrmonio natural. O rhPTH é clinicamente indicado para o tratamento da osteoporose de alto risco de fraturas em mulheres pós-menopausa, de homens com osteoporose primária ou hipogonadal, e da osteoporose associada à terapia sistêmica com glicocorticóides. Neste trabalho foi desenvolvido e validado método por eletroforese capilar de zona (ECZ) para a avaliação de rhPTH em produtos biofarmacêuticos. No método por ECZ, utilizou-se capilar de sílica fundida (40 cm de comprimento efetivo x 50 μm d.i.) e solução eletrolítica composta de fosfato de sódio dihidrogenado 50 mM, pH 3,0. O capilar foi mantido a temperatura de 25ºC, e a tensão aplicada foi de 20 kV. O tempo de injeção foi de 45 s, com pressão de 50 mBar, e detecção por arranjo de diodos (DAD), em 200 nm. A separação eletroforética foi obtida com tempo de migração de 5,3 min, sendo linear na faixa de concentração de 0,25-250 μg/mL (r2 = 0,9992). Os limites de detecção e quantificação foram de 0,12 e 0,40 μg/mL, respectivamente. A especificidade foi avaliada através de análises com os excipientes da formulação biofarmacêutica e estudos de degradação, demonstrando a seletividade do método. A exatidão foi 100,28% com bias inferior a 0,85%. Além disso, realizou-se o teste de citotoxicidade in vitro das formas degradadas, apresentando, para as amostras submetidas às condições ácida, fotolítica e térmica, diferença significativa (p< 0,05) em relação à molécula íntegra. Os bioensaios de proliferação celular e da atividade da fosfatase alcalina em células UMR-106 foram desenvolvidos e aplicados para avaliação da atividade biológica de rhPTH em formulações biofarmacêuticas. Os resultados de teor/potência foram correlacionados com os métodos já validados por cromatografia líquida em fase reversa (CL-FR), cromatografia líquida por exclusão molecular (CL-EM) e ECZ, apresentando correlação significativa (p> 0,05). Assim, sugere-se que o métodos físico-químicos validados sejam aplicados paralelamente aos bioensaios in vitro para aprimorar o controle da qualidade do produto biotecnológico de rhPTH, e para avaliação da biossimilaridade de rhPTH.
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Barakat, Fatima. "Développement de méthodes analytiques pour l’analyse d’oligonucléotides thérapeutiques bio-conjugués à des lipides." Thesis, Bordeaux, 2020. http://www.theses.fr/2020BORD0292.

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Les oligonucléotides antisens (ASO) ont la capacité d’inhiber ou de moduler l’expression d’un gène cible par différents mécanismes. La bioconjugation de l’ASO avec un lipide est une approche très prometteuse qui a montré une amélioration de la délivrance de la séquence antisens et par conséquent, de l’efficacité thérapeutique de l’oligonucléotide. Ces nouveaux agents thérapeutiques, les oligonucléotides lipidiques (LON), sont des molécules amphiphiles capables de s’auto-assembler sous forme d’objets supramoléculaires. Leur développement pharmaceutique requiert des méthodes analytiques adaptées pour évaluer la pureté des LON synthétisés et pouvoir les quantifier dans les formulations mais aussi pour caractériser les assemblages supramoléculaires formés.Dans ce travail, différentes méthodes ont été évaluées en chromatographie liquide (HPLC) à polarité de phase inversée par appariement d’ions et à interactions hydrophiles, en électrophorèse capillaire (CE) et en chromatographie d’exclusion stérique (SEC) pour l’analyse de LON de structures chimiques variées. Malgré les nombreux paramètres étudiés, l’asymétrie des pics obtenus en HPLC, limite son utilisation à des fins de dosage. En revanche, une méthode quantitative a été développée et validée en CE en présence de cyclodextrines (CD). La constante de complexation entre le LON libre et les CD ainsi que la mobilité électrophorétique du complexe ont été déterminées. Enfin, le potentiel de la SEC et de la CE pour la caractérisation des objets supramoléculaires de LON a été évalué
Antisense oligonucleotides (ASO) have the ability to inhibit or modulate the expression of a target gene by various mechanisms. Bioconjugation of ASO with a lipid is a very promising approach which has shown an improvement in the delivery of the antisense sequence and therefore, in the therapeutic efficacy of the oligonucleotide. These new therapeutic agents, lipid oligonucleotides (LON), are amphiphilic molecules and are able to self-assemble to form supramolecular objects. Their pharmaceutical development requires suitable analytical methods to study the purity of the LONs synthesized and to be able to quantify them in the formulations but also to characterize the supramolecular assemblies formed.In this work, different methods were investigated in ion-pairing reversed-phase HPLC and hydrophilic interaction chromatography, capillary electrophoresis (CE) and size exclusion chromatography (SEC) for LON analysis with various chemical structures. Despite the different parameters studied, the asymmetry of the peaks obtained by HPLC limits its use for assays. On the other hand, a quantitative method has been developed and validated in CE in the presence of cyclodextrins (CD). The complexation constant between free LON and CDs as well as the electrophoretic mobility of the complex were determined. Finally, the potential of SEC and CE for the characterization of supramolecular objects of LON was assessed
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Raak, Norbert, Raffaele Andrea Abbate, Albena Lederer, Harald Rohm, and Doris Jaros. "Size Separation Techniques for the Characterisation of Cross-Linked Casein: A Review of Methods and Their Applications." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-234862.

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Casein is the major protein fraction in milk, and its cross-linking has been a topic of scientific interest for many years. Enzymatic cross-linking has huge potential to modify relevant techno-functional properties of casein, whereas non-enzymatic cross-linking occurs naturally during the storage and processing of milk and dairy products. Two size separation techniques were applied for characterisation of these reactions: gel electrophoresis and size exclusion chromatography. This review summarises their separation principles and discusses the outcome of studies on cross-linked casein from the last ~20 years. Both methods, however, show limitations concerning separation range and are applied mainly under denaturing and reducing conditions. In contrast, field flow fractionation has a broad separation range and can be easily applied under native conditions. Although this method has become a powerful tool in polymer and nanoparticle analysis and was used in few studies on casein micelles, it has not yet been applied to investigate cross-linked casein. Finally, the principles and requirements for absolute molar mass determination are reviewed, which will be of increased interest in the future since suitable calibration substances for casein polymers are scarce.
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"Foundational Investigation of Electrophoretic Exclusion." Doctoral diss., 2015. http://hdl.handle.net/2286/R.I.36375.

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abstract: Electrophoretic exclusion is a counter-flow gradient focusing method that simultaneously separates and concentrates electrokinetic material at a channel entrance utilizing electric and fluid velocity fields. However, its effectiveness is heavily dependent on the non-uniform field gradients about the entrance. This work assesses the capability of electrophoretic exclusion to capture and enrich small molecules and examines the channel entrance region both quantitatively and qualitatively to better understand the separation dynamics for future design. A flow injection technique is used to experimentally evaluate electrophoretic exclusion of small molecules. Methyl violet, a cationic dye, and visible spectroscopy are used to monitor flow and electrophoretic dynamics at the entrance region resulting in successful capture and simultaneous enrichment of methyl violet at the channel interface. Investigation of the entrance region is performed using both experiment data and finite element analysis modeling to assess regional flow, electric fields, diffusion, convection, and electrophoretic migration. Longitudinal fluid velocity and electric field gradient magnitudes near the channel entrance are quantified using Particle Tracking Velocimetry (PTV) and charged fluorescent microspheres. Lateral studies using rhodamine 123 concentration monitoring agree qualitatively with simulation results indicating decreased gradient uniformity for both electric and fluid velocity fields closer to the channel wall resulting in a localized concentration enhancement at lower applied voltages than previously observed or predicted. Resolution interrogation from both a theoretical assessment and simulation construct demonstrate resolution improvement with decreased channel width and placement of an electrode directly at the interface. Simulation resolution predictions are in general agreement with early experimental assessments, both suggesting species with electrophoretic mobilities as similar as 10-9 m2/(Vs) can be separated with the current design. These studies have helped evolve the understanding of the interface region and set the foundation for further interface developments.
Dissertation/Thesis
Doctoral Dissertation Chemistry 2015
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"Adapting Electrophoretic Exclusion to a Microdevice." Doctoral diss., 2012. http://hdl.handle.net/2286/R.I.15880.

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abstract: Complex samples, such as those from biological sources, contain valuable information indicative of the state of human health. These samples, though incredibly valuable, are difficult to analyze. Separation science is often used as the first step when studying these samples. Electrophoretic exclusion is a novel separations technique that differentiates species in bulk solution. Due to its ability to isolate species in bulk solution, it is uniquely suited to array-based separations for complex sample analysis. This work provides proof of principle experimental results and resolving capabilities of the novel technique. Electrophoretic exclusion is demonstrated at a single interface on both benchtop and microscale device designs. The benchtop instrument recorded absorbance measurements in a 365 μL reservoir near a channel entrance. Results demonstrated the successful exclusion of a positively-charged dye, methyl violet, with various durations of applied potential (30 - 60 s). This was the first example of measuring absorbance at the exclusion location. A planar, hybrid glass/PDMS microscale device was also constructed. One set of experiments employed electrophoretic exclusion to isolate small dye molecules (rhodamine 123) in a 250 nL reservoir, while another set isolated particles (modified polystyrene microspheres). Separation of rhodamine 123 from carboxylate-modified polystyrene spheres was also shown. These microscale results demonstrated the first example of the direct observation of exclusion behavior. Furthermore, these results showed that electrophoretic exclusion can be applicable to a wide range of analytes. The theoretical resolving capabilities of electrophoretic exclusion were also developed. Theory indicates that species with electrophoretic mobilities as similar as 10-9 cm2/Vs can be separated using electrophoretic exclusion. These results are comparable to those of capillary electrophoresis, but on a very different format. This format, capable of isolating species in bulk solution, coupled with the resolving capabilities, makes the technique ideal for use in a separations-based array.
Dissertation/Thesis
Ph.D. Chemistry 2012
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10

"Foundational Studies for Array-based Electrophoretic Exclusion of Proteins." Doctoral diss., 2019. http://hdl.handle.net/2286/R.I.53824.

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abstract: Disease prevention and personalized treatment will be impacted by the continued integration of protein biomarkers into medical practice. While there are already numerous biomarkers used clinically, the detection of protein biomarkers among complex matrices remains a challenging problem. One very important strategy for improvements in clinical application of biomarkers is separation/preconcentration, impacting the reliability, efficiency and early detection. Electrophoretic exclusion can be used to separate, purify, and concentrate biomarkers. This counterflow gradient technique exploits hydrodynamic flow and electrophoretic forces to exclude, enrich, and separate analytes. The development of this technique has evolved onto an array-based microfluidic platform which offers a greater range of geometries/configurations for optimization and expanded capabilities and applications. Toward this end of expanded capabilities, fundamental studies of subtle changes to the entrance flow and electric field configurations are investigated. Three closely related microfluidic interfaces are modeled, fabricated and tested. A charged fluorescent dye is used as a sensitive and accurate probe to test the concentration variation at these interfaces. Models and experiments focus on visualizing the concentration profile in areas of high temporal dynamics, and show strong qualitative agreement, which suggests the theoretical assessment capabilities can be used to faithfully design novel and more efficient interfaces. Microfluidic electrophoretic separation technique can be combined with electron microscopy as a protein concentration/purification step aiding in sample preparation. The integrated system with grids embedded into the microdevice reduces the amount of time required for sample preparation to less than five minutes. Spatially separated and preconcentrated proteins are transferred directly from an upstream reservoir onto grids. Dilute concentration as low as 0.005 mg/mL can be manipulated to achieve meaningful results. Selective concentration of one protein from a mixture of two proteins is also demonstrated. Electrophoretic exclusion is also used for biomarker applications. Experiments using a single biomarker are conducted to assess the ability of the microdevice for enrichment in central reservoirs. A mixture of two protein biomarkers are performed to evaluate the proficiency of the device for separations capability. Moreover, a battery is able to power the microdevice, which facilitates the future application as a portable device.
Dissertation/Thesis
Doctoral Dissertation Chemistry 2019
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Books on the topic "Electrophoretic exclusion"

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Lepane, Viia. Characterization of aquatic humic substances by size exclusion chromatography and capillary electrophoresis. Tallinn: TTU Press, 2001.

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Book chapters on the topic "Electrophoretic exclusion"

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Malsch, Reinhard, Job Harenberg, Lukas Piazolo, and Dieter L. Heene. "Inequivalence of Glycosaminoglycans Using High-Performance Size Exclusion Chromatography, Polyacrylamide Gel Electrophoresis and High-Performance Capillary Electrophoresis." In Nonanticoagulant Actions of Glycosaminoglycans, 1–14. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-1-4613-0371-8_1.

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Tse, Season, and Anne-Laurence Dupont. "Measuring Silk Deterioration by High-Performance Size-Exclusion Chromatography, Viscometry, and Electrophoresis." In ACS Symposium Series, 98–114. Washington, DC: American Chemical Society, 2000. http://dx.doi.org/10.1021/bk-2001-0779.ch008.

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Hoagland, David A. "Unified Thermodynamic Model for Polymer Separations Produced by Size Exclusion Chromatography, Hydrodynamic Chromatography, and Gel Electrophoresis." In ACS Symposium Series, 173–88. Washington, DC: American Chemical Society, 1996. http://dx.doi.org/10.1021/bk-1996-0635.ch010.

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Berkowitz, Steven A. "Chromatography (other than size-exclusion chromatography) and electrophoresis." In Biophysical Characterization of Proteins in Developing Biopharmaceuticals, 431–56. Elsevier, 2020. http://dx.doi.org/10.1016/b978-0-444-64173-1.00014-7.

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De Nobili, Maria, Gilberto Bragato, and Antonella Mori. "MOLECULAR SIZE DISTRIBUTION OF HUMIC SUBSTANCES: A COMPARISON BETWEEN SIZE EXCLUSION CHROMATOGRAPHY AND CAPILLARY ELECTROPHORESIS." In Understanding Humic Substances, 101–6. Elsevier, 1999. http://dx.doi.org/10.1016/b978-1-85573-815-7.50015-5.

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Conference papers on the topic "Electrophoretic exclusion"

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Zangle, Thomas A., Ali Mani, and Juan G. Santiago. "Experimental Study of Concentration Polarization at a Microchannel-Nanochannel Interface." In ASME 2007 International Mechanical Engineering Congress and Exposition. ASMEDC, 2007. http://dx.doi.org/10.1115/imece2007-42324.

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Recent advances in fabrication methods allow us to study and leverage the unique flow regimes offered by nano-scale fluidic channels, [1–3] and recent work suggests that the physics of microchannel/nanochannel interfaces present opportunities for novel methods of sample preconcentration and analysis. [4–6] In nanochannels, channel height is of the same order of the electric double layer (EDL) thickness, leading to a decreased electrical resistance relative to the fluidic resistance of the channel. More importantly, analyte molecules undergoing electrophoresis spend a significant amount of time within EDLs. This has a profound effect on the interfaces between micro- and nanochannels. In particular, for negatively charged walls and a nanochannel in series with two microchannels, the concentration of ions (of both signs) increases on the cathodic side of the nanochannel and decreases on the anodic side. This phenomenon is called concentration polarization (CP) or the exclusion enrichment effect. [4, 5] There is a dearth of basic studies of these phenomena and the coupling of electroosmotic flow with concentration polarization. We present experimental validation of a computational model which predicts the development of concentration polarization. Furthermore, we will show preliminary results demonstrating focusing and separation of analyte anions in the cathodic side microchannel. This focusing is due to a balance of advection and electrophoretic migration. Anionic analytes focus and separate according to electrophoretic mobility.
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Stachowiak, Jeanne C., Erin E. Shugard, Pamela Caton, Bruce P. Mosier, Ron Renzi, Rafael V. Davalos, Gregory J. McGraw, Blake A. Simmons, Victoria A. Vandernoot, and Brent A. Haroldsen. "Automated Sample Preparation System for Rapid Biological Threat Detection." In ASME 2005 International Mechanical Engineering Congress and Exposition. ASMEDC, 2005. http://dx.doi.org/10.1115/imece2005-80945.

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Rapid, automated sample preparation of bacterial cells and spores is required for threat analysis by remotely deployed chemical and biological warning systems. Sandia is designing, building, and testing an automated front-end sample preparation system based on miniature and microfluidic components, with the goal of concentrating bacterial species collected from the air, harvesting and solubilizing proteins from them, and delivering them to Sandia’s MicroChemLab capillary gel electrophoresis system1,2 for analysis (Fig. 1). Miniature, motorized valves and pumps control flow between system components connected by fused silica capillaries (Fig. 4). Sample processing modules include concentration by dielectrophoresis in an array of insulating posts or by mechanical filtration; heat-activated chemical lysis; mechanical filtration; removal of chemical lysis agents by size exclusion chromatography (SEC); and in-capillary fluorescent labeling.
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Cheung, A., and K. F. Hebert. "A TUMOR SERINE PROTEASE INHIBITOR WHICH MAY FUNCTION AS A TISSUE PLASMINOGEN ACTIVATOR INHIBITOR." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1644448.

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A protease inhibitor has been isolated from human colorectal adenocarcinomas by extraction with a low ionic strength-buffer and a combination of concanavalin A-Sepharose, Sephadex G-200, DEAE cellulose and chromatofocusing steps. The preparation appeared to be homogeneous upon gel exclusion chromatography and SDS polyacrylamide gel electrophoresis. It had an apparent Mr of ~66,000 and its isoelectric point was 4.6-4.7. The inhibitor was able to bind and inhibit urokinase, plasmin, trypsin, tissue plasminogen activator and thrombin. The bindings appeared to be stoichiometric and relative fast and diisopropylfluorophoshphate interfered with the bindings. However tPA was the only enzyme that was inhibited in a linear concentration-dependent manner.The inhibitor crossreacted with antiserum against al-antitrypsin but not with antisera against β2-macroglobulin, α2-antiplasmin, antithrombin III, or Cl-inhibitor. Whereas αl-antitrypsin completely inhibited the amidolytic activity of elastase, the tumor inhibitor had no effect on elastase under the same conditions.
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Liu, Kelvin J., Tushar D. Rane, Yi Zhang, Cyrus W. Beh, Sarah M. Friedrich, Dong Jin Shin, and Tza-Huei Wang. "An Integrated Platform for Single Molecule Free Solution Hydrodynamic Separation Using Yoctomoles of DNA and Picoliter Samples." In ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icnmm2012-73154.

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We report a microfluidic platform for sizing and separation of DNA called PicoSep that is among the most sensitive to date, requiring only yoctomoles of DNA (10−24 moles) and picoliters of sample (<10 pL). The cohesive integration of cylindrical illumination confocal spectroscopy based (CICS) single molecule counting with free solution hydrodynamic separation increases detection sensitivity >103-fold over traditional laser induced fluorescence (LIF) and vastly improves quantification accuracy. Separation is performed via single molecule free solution hydrodynamic separation (SML-FSHS). SML-FSHS relies on the wall exclusion mechanism to separate DNA as it is driven down buffer filled microchannel. High separation efficiency (plate number = 105 – 106) and high sizing resolution (37 bp – 2.1 kbp) are obtained across a wide dynamic range of DNA (100 bp – 27 kbp) in a single separation. Quantitative accuracy up to the limits imposed by molecular shot noise is achieved, and a limit of detection <20 molecules is demonstrated. Through the development of PicoSep, we have significantly reduced the cost and complexity of single molecule instrumentation while achieving sizing and quantification performance that surpasses capillary electrophoresis (CE). Unlike CE, no viscous sieving matrices, high voltage power supplies, or capillary wall coatings are necessary, making devices inexpensive, simple to fabricate, and easy to incorporate into lab on a chip systems.
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Niiya, K., P. Kostel, T. S. Zimmerman, and Z. M. Ruggeri. "CHARACTERIZATION OF A 40 kDa FRAGMENT OF VON WILLEBRAND FACTOR THAT CONTAINS THE GLYCOPROTEIN IIb/IIIa-BINDING DOMAIN." In XIth International Congress on Thrombosis and Haemostasis. Schattauer GmbH, 1987. http://dx.doi.org/10.1055/s-0038-1642874.

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We have isolated a 40 kDa fragment of von Willebrand factor (vWF) that contains the glycoprotein (GP) Ilb/IIIa-binding domain. The Staphylococcus aureus V8 protease-generated fragment II was digested with trypsin (1:50 enzyme:substrate ratio on a weight-to-weight basis). After addition of a 100fold molar excess of (p-amidinophenyl)methanesulfonyl fluoride in order to inhibit any residual trypsin activity, the whole digest was subjected to ion-exchange and size-exclusion high pressure liquid chromatography. Two major fragments were separated. Analysis by polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate (SDS) demonstrated that one of the two purified polypeptides had an apparent molecular weight of 40 kDa under both reducing and nonreducing conditions, suggesting that it was a single chain polypeptide. The other fragment had an apparent molecular weight of 22 kDa after reduction and 44 kDa unreduced, suggesting that it was a homodimer. Amino terminal sequence analysis of both fragments was performed by classical Edman degradation following electroelution from reduced SDS-polyacrylamide gels. The amino terminus of the 40 kDa fragment corresponded to residue Glu (1366) (as did the fragment II from which it was derived), while the amino terminus of the 22 kDa fragment corresponded to residue Val (1927) of the constituent 2050 residue subunit. The effect of both fragments on vWF binding to the platelet membrane GP IIb/IIIa complex was evaluated by measuring the residual binding of 125I-labeled vWF to thrombin-stimulated platelets in the presence of varying amounts of the unreduced fragments. The 40 kDa polypeptide inhibited 64 percent of vWF binding when tested at a concentration of 20 μK, whereas the 22kDa dimer was without effect. This study establishes that the GP IIb/IIIa-binding domain of vWF resides in a discrete, single-chain 40 kDa fragment derived from the 220 kDa, homodimeric fragment II generated by V8 protease. Moreover, we found evidence for the existence of inter-chain disulfide bonds within 22 kDa from the carboxyl terminus of the constituent subunit.
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