Capillary electrophoresis often uses complexing agents since the interaction between the analyte and the complexing agent can result in achieving or improving the separation. Examples of such methods can be electrokinetic chromatography or affinity capillary electrophoresis (ACE). ACE is used to determine the complexing parameters. In case of chiral separation, this issue gets complicated, since the parameters of the two analytes (enantiomers) are not completely independent to one another. Therefore, a procedure has been proposed in this thesis, that should always be used to evaluate the complexing parameters of two enantiomers. Statistical evaluation of these parameters was assessed as well. This work also proposes a method that allows to determine the relative migration order of two enantiomers in two different complexing separation systems. The mathematical description of electrophoresis is based on continuity equations, that are inherently nonlinear. However, these equations can be linearized to obtain an approximate analytical solution. There was recently presented a generalized model, that enables inclusion of complete complexing equilibria in the theoretical description of electromigration. Thus, various phenomena, including nonlinear ones, associated with complexation can be predicted. This...

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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.

De nos jours, la stéréochimie des médicaments est devenue un enjeu important aussi bien pour l'industrie pharmaceutique que pour les autorités réglementaires. Il a été démontré que les nucléotides / nucléosides ou les structures en double hélice et tétrade de guanine présentaient certaines propriétés énantio sélectives. Néanmoins, à ce jour, très peu d’études se sont focalisées sur l’utilisation de l’ADN en tant que sélecteur chiral. Grâce à l’utilisation d’une méthode de remplissage partiel, les propriétés de discrimination chirale d'un répertoire d'oligonucléotides (ONs) en série ADN caractérisé par diverses compositions de bases et de structures ont été testées sur une large gamme de mélanges racémiques par électrophorèse capillaire (EC), méthode séparative performante utilisant de faibles volumes d’échantillons. A des concentrations d'ADN sub-millimolaire, il a été montré que tous les ONs en série ADN testés, présentaient des capacités d'énantio discrimination vis-à-vis de plusieurs composés pertinents. Les couples d’énantiomères séparés sont, soit des composés cationiques possédant un groupement phényle, soit des analytes sans charge nette ou avec une charge positive et comportant deux cycles aromatiques. Une étude portant sur les capacités séparatives de plusieurs séquences d'homopolymères poly-dT de longueurs différentes (de 5 à 60-mer) a ensuite été menée sur certains couples d’énantiomères. Les résultats ont montré qu’une longueur minimale de 30 bases, où l'ADN semble adopter une conformation de type pelote, présentait de meilleures propriétés d'énantioséparation qu’une séquence constituée d’un maximum de 10 bases. De plus, la reconnaissance chirale des ONs en série ADN implique principalement des bases d'ADN libres dont la diversité chimique augmente leur capacité d'énantio résolution. Finalement, afin d'étudier la contribution thermodynamique impliquée dans les séparations énantiomériques obtenues par les ONs simples brins testés, des mesures de constantes d’affinité pour les énantiomères du tryptophane ont été réalisées vis-à-vis du Poly-dT30 par trois techniques différentes. Les méthodes utilisées n’ont pas permis de déterminer une différence d’affinité entre les deux énantiomères. / Nowadays, drug stereochemistry has become a significant issue for both the pharmaceutical industry and the regulatory authorities. It has been demonstrated that nucleotides/ nucleosides or duplex and G-quadruplex structures showed some enantioselective properties. Nevertheless, to date, the use of DNA as chiral selector has been largely neglected. Using partial filling capillary electrophoresis (CE) method, highly efficient technique with little volume consumption need, the assessment of the enantioselective properties of a repertoire of arbitrarily chosen DNA oligonucleotides (ONs) characterized by diverse base compositions and structural features was studied for a series of various racemates. Under (sub) millimolar DNA concentration conditions, it was shown that all the ONs tested presented enantiodiscrimination properties for interesting organic compounds. The resolved compounds are either cationic carrying one phenyl group or contain two aromatic cycles with no net or one positive charge. Then, sequence prerequisites of ONs for the CE enantioseparation process were studied for a series of homopolymeric sequences (Poly-dT) of different lengths (from 5 to 60-mer) and for the discrimination of various enantiomers. The results showed that the sequence length of 30-mer (or more) of the ONs was better for the enantioseparation properties, where the DNA adopted a coil-like conformation, than ONs with a sequence length ≤ 10-mer. The base-unpaired state constituted also an important factor in the chiral resolution ability of ONs. Moreover, the chemical diversity enhanced the enantioresolution ability of single-stranded ONs. Finally, several attempts have been conducted to study the thermodynamic contribution involved in enantiomeric separation obtained with DNA strands. Binding affinity constants were determined for tryptophan enantiomers towards Poly-dT30 by three different techniques. The used methods did not allow determining a difference of affinity between enantiomers.

Vanliga fenoliska antioxidanter som används i polymerer orsakar färgändringar i polymeren. Detta arbete berör antioxidanter med jämförelsevis begränsad färgändring, med fokus på att utveckla metoder för analys av dessa. UV-stabilisatorerna UV2, UV5, UV1, UV4, UV3 och UV6 är också inkluderade i detta arbete. Metodutvecklingen involverade både kapillärelektrofores och ”matrix assisted laser desorption ionization-time of flight mass spectrometry” (MALDI-TOF). Den bästa metoden för analys av de flesta av additiven inkluderade MALDI-TOF med 2’,6’-dihydroxyacetophenon (10 mg/ml) i TA50 som matris och hexafluoroisopropanol som lösningsmedel. När en metod för detektion av analyterna hade tagits fram, så inleddes utveckling av en metod för extraktion av additiv från polymera material. Extraktion av UV5 var framgångsrik vid användning av toluen vid 80 °C i ultraljudsbad i tre timmar. Det extraherade UV5 detekterades sedan med metoden som hade utvecklats för det rena additivet. / Ordinary phenolic antioxidants used in polymers give rise to color formations. This work concerns antioxidants with limited color-formations in comparison, with the focus being development of methods for analysis of these. Also included in this work are the high molecular weight UV-stabilizers UV2, UV5, UV1, UV4, UV3 and UV6. The method development involved both capillary electrophoresis and matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF). The best method for analysis of most additives involved using MALDI-TOF with a matrix consisting of 2’,6’-dihydroxyacetophenone (10 mg/ml) in TA50 and with hexafluoro isopropanol as the solvent. When a method for detection of the analytes had been obtained, a method for extraction of the additives from polymers was developed. UV5 was successfully extracted using toluene as the extracting solvent at 80 °C under sonication for three hours. The extracted UV5 was then detected using the method developed for the pure additive.

In this thesis the possibilities of using capillary electrophoresis as a separation technique for analysis of proteins and microbubbles is presented. A complete analytical process consists of five necessary steps of which one is the actual analysis step. For this step a suitable analytical technique is needed. Capillary electrophoresis (CE) is one of the common analytical separation techniques used for analysis of a diversity of analytes, and can be both used in routine analysis and for research purposes. The reason for using CE, compared to other liquid-based separation techniques, is mainly short analysis time, high resolution, and negligible sample volumes and solvent waste. Depending on the characteristics of the analytes, and the sample matrix, different modes of CE can be used, where capillary zone electrophoresis (CZE) is the most employed one. The basic principle of CZE is separation of the analytes due to differences in total mobility, which is dependent on the charge and size of the analytes, and the electroosmotic flow (EOF). The EOF can be controlled by several parameters e.g. choice of background electrolyte (BGE), and the optimization of the parameters has been discussed throughout the thesis. To improve the properties of the BGE, an ethylammonium nitrate (EAN) water solution was used as BGE for CE analysis in Paper I. The precision of the EOF with this method was determined by adjusting the pH of the BGE, the concentration of EAN in the BGE, and the electric field. Model proteins were thereafter analysed using the optimal parameters yielding a precision sufficient for routine control. One example of the applications of CE is separation of novel contrast agents, which consist of polyvinyl alcohol microbubbles (PVA-MBs). In Paper II, a method for analysis of PVA-MBs in biological samples using CE with UV-detection was developed. It was also established that intact PVA-MBs could be distinguished from ultrasound degraded PVA-MBs in the same set-up. / <p>QC 20171012</p>

<p> The development of high-quality screening assays for the identification of biologically active ligands is critical in drug discovery. This thesis is aimed at developing new advances m capillary electrophoresis (CE) for the characterization of the conformational stability and enzymatic activity of protein targets with small molecules. CE provides a convenient platform for unbiased assessment of multiple thermodynamic and kinetic parameters associated with biomolecular interactions involving regulatory protein or isomerase enzymes, where various sample pretreatment steps can be integrated directly in-capillary during analysis. The first two chapters of the thesis (Chapters II, III) outline the development of dynamic ligand exchange-affinity capillary electrophoresis (DLEACE) as a novel strategy for the screening of allosteric ligands based on the differential stability of urea-induced unfolding of various apolholo-protein states of cAMP receptor protein constructs. This work introduced a label-free and multivariate approach for ligand selection based on complementary thermodynamic parameters that allowed for determination of the dissociation constant of protein-ligand interactions over a wide dynamic range (> 10^4, Kd = nM-mM). The subsequent two chapters of the thesis (Chapters IV, V) describe the development of a novel kinetic assay for unbiased characterization of isomerase activity associated with D/L-amino acid metabolism using hydroxyproline epimerase as a model system. Stereoselective resolution of various hydroxyproline isomers was accomplished via off-line or on-line chemical derivatization with dynamic complexation usmg chiral selector(s) in order to screen potential inhibitors for putative epimerase and racemase activity. The integration of both thermodynamic and kinetic strategies for differentiation of mutant from wild-type enzymes was important for revealing the function of a catalytic acid/base cysteine pair in the epimerase active site. Overall, this thesis outlines an integrative framework based on CE for high-quality screening, which is relevant in reducing the high attrition rate of lead candidates in drug development. </p> / Thesis / Doctor of Philosophy (PhD)

Biological markers (i.e., biomarkers) are essential in clinical and epidemiological studies as they may provide mechanistic insights into the developmental origins of disease, as well as improve diagnostic testing and risk assessment for disease prevention. However, major challenges remain due to the lack of rapid yet selective analytical methods for high throughput screening that are also amenable to volume-restricted specimens. This thesis includes two major research themes that take advantage of capillary electrophoresis (CE) separations, including (1) the targeted analysis of urinary iodide and thiocyanate for assessment of nutritional adequacy and tobacco smoke exposures in the population, and (2) the discovery of new biomarkers in sweat specimens that may improve universal newborn screening programs for cystic fibrosis (CF) infants beyond impaired chloride transport. Chapter II examines the prevalence and risk factors associated with iodine deficiency in 24 h urine samples collected from 800 participants across four clinical sites in Canada as part of the Prospective Urban and Rural Epidemiological (PURE) study when using CE with UV detection in conjunction with sample self-stacking. Importantly, regional variations in iodine status were revealed with participants from Quebec City and Vancouver at greater risk for iodine deficiency than Hamilton and Ottawa. Overall, iodine supplement use, thyroxine prescription, urinary sodium excretion, and self-reported dairy intake were found to be protective factors against iodine deficiency. Chapter III applied a validated CE assay to measure urinary thiocyanate as a biomarker of tobacco smoke and dietary exposures in an international cohort of 1000 participants from the PURE study spanning 14 countries with varied income status, smoking habits, and diet quality. Current smokers residing in high-income countries had the highest extent of cyanide exposure indicative of greater harms from tobacco smoke compared to middle- and low-income countries after adjusting for smoking intensity and other covariates. Chapter IV introduces a rapid CE method with indirect UV detection to simultaneously measure sweat chloride and bicarbonate from presumptive CF infants’ residual sweat samples. Although bicarbonate did not provide clinical value in neonatal CF diagnosis, sweat chloride testing by CE may reduce test failure rates due to insufficient volumes from infants in a clinical setting. Lastly, Chapter V applied an untargeted strategy to characterize the sweat metabolome from presumptive CF infants when using multisegment injection-capillary electrophoresis-mass spectrometry (MSI-CE-MS). A panel of sweat metabolites were found to discriminate CF from non-CF (i.e., unaffected carriers) infants, including aspartic acid, glutamine, oxoproline, and pilocarpic acid, which also correlated with sweat chloride. The clinical utility of these sweat metabolites to prognosticate late-onset CF infants from indeterminate sweat chloride test results was also explored. In summary, this thesis contributes innovative separation methods for biomarker screening and discovery in clinical and epidemiological studies for the prevention and early treatment of human diseases that benefit from optimal nutrition. / Dissertation / Doctor of Philosophy (PhD)

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