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Polymer brushes are extremely versatile materials, as monomer choice allows the user to design a material with the desired physiochemical properties. Given the wide variety in monomer functionality, polymers can be fine-tuned for a specific application. In this work, polymer brushes bound to a silica support are designed and utilized to enhance performance of protein extraction and chromatographic separations. <br> The effectiveness of an analytical method is strongly affected by matrix composition, however, the presence of species other than the target analyte is usually unavoidable. An excellent technique will be able to identify and/or quantify the analyte even when its concentration is low compared with interfering molecules. Protein analysis is particularly challenging, since many proteins of clinical and scientific significance are present in complicated matrices such as plasma or cell lysates. <br>A common method to specifically separate a protein from a complicated matrix is solid phase extraction. In this method, a species (such as an antibody) with high specificity towards the target is immobilized onto a solid substrate (commonly beads or small particles for greater surface area). Next, the target is collected onto the surface, bound by the species. The solid substrate is rinsed of the liquid matrix, before elution of the target. Only the active species should interact with the analyte, and the surface should be otherwise inactive. However, nonspecific interactions lead to binding/adsorption of undesirable compounds. Therefore, an optimal substrate for protein extraction must be 1) easily and completely removable from the liquid phase, 2) have a high concentration of active sites for specific binding, and 3) exhibit low nonspecific binding. As part of this work, commercial magnetic particles were coated with a nonporous silica layer that tolerates the acid bath and silane coating necessary to attach a polymer layer. On the silane coating, a polymer layer was covalently bound; this layer contains epoxide active groups for immobilizing antibodies. These antibodies bind to the target molecule with high specificity, and low nonspecific binding. Obtained particles were evaluated for protein extraction, where antibodies as well as specifically engineered drug compounds were successfully bound to the particle surface.<br>Glycosylation influences several physiopathological processes in proteins. Glycans can act as receptors, modify protein solubility, and participate in folding conformation. Altered glycosylation is a common feature in tumorous cells. As such, many modifications in glycoproteins have been related to cancer, including increased branching of N-glycans or augmented units of sialic acid. Therefore, characterization of glycoproteins is important not only as a diagnostic tool, but also to monitor patients’ response to treatment. Furthermore, it is important in the growing field of monoclonal antibodies as drug carriers. <br>Among different methods used for glycosylation analysis, Hydrophilic Interaction Liquid Chromatography (HILIC) has showed important advantages over time-consuming digestion-MS based techniques. An adequate HILIC stationary phase can be used to rapidly differentiate glycoforms present in a sample. In the second part of this work, a polymer brush based bonded phase was developed as a HILIC stationary phase. The new polymer improved the separation of a model glycoprotein compared with a commercial HILIC column, while also exhibiting enhanced stability over a previous bonded phase synthetized in our group.<br><br>

The objective of this research is to develop and apply a HILIC UHPLC stationary phase that allows for separation of intact glycoproteins. In Chapter 1 I give an overview of the problems of current glycosylation profiling with regards to biotherapeutics, and my strategy to separate the intact glycoprotein with HILIC. Chapter 2 describes the methods used to produce the nonporous packing material and stationary phase. In Chapter 3 I describe previous work in developing a HILIC polyacrylamide stationary phase, and further improvements I have made. Chapter 4 describes development of an assay in collaboration with Genentech of therapeutic mAb glycosylation. In Chapter 5, I show HILIC-MS of digested ribonuclease B as a beginning step to analyze glycosylated biomarkers.

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Cette thèse rapporte le greffage chimique de brosses de polymères neutres de poly(acrylate de tert-butyle) (PtBA) et de brosses chargées d’acide polyacrylique (PAA) sur des substrats de mica afin d’étudier leur conformation en fonction de la densité de greffage, du pH et de la force ionique. Le greffage est réalisé par polymérisation contrôlée par transfert d’atome (ATRP) initiée depuis la surface de mica afin de contrôler la croissance du polymère et sa densité de greffage. L’étude de la conformation des brosses de PtBA et de PAA a été menée avec la technique AFM en mesurant les épaisseurs des films à sec et gonflés sous différentes conditions de solvant, de pH et de force ionique. Une monocouche d’amorceurs est tout d’abord greffée sur du mica porteur de groupes hydroxyles créés par plasma (Ar/H2O). Cette couche a été caractérisée par des mesures d’angle de contact et par la technique TOF-SIMS. L’amorceur greffé a ensuite permis d’initier l’ATRP directement depuis la surface pour former des brosses neutres de PtBA liés de façon covalente au mica. La croissance linéaire de l’épaisseur du film avec la masse molaire du polymère en solution et le taux de conversion montre que la polymérisation est contrôlée. De plus, la ré-initiation des chaînes greffées atteste du caractère vivant de la polymérisation. L’hydrolyse des brosses de PtBA, confirmée par des mesures d’angle de contact, d’épaisseur et par FT-IR, conduit à des brosses de PAA. Les différentes couches greffées sont stables à l’air, en milieu organique et en milieu aqueux et leur gonflement est réversible. Le degreffage de la couche de PAA est observé suite à une longue exposition à pH basique. Cette étude représente le premier exemple de brosses greffées chimiquement sur du mica par polymérisation initiée depuis la surface. La variation des paramètres de la réaction de greffage de l’amorceur, tels que la concentration et la durée de réaction, a permis de contrôler le taux de recouvrement de l’amorceur et la densité de greffage du polymère. Une grande gamme de taux de recouvrement de l’amorceur est accessible et se traduit par un intervalle de densités de greffage allant de faibles à élevées (e.g. 0,04 chaîne/nm2 à 0,5 chaîne/nm2). L’étude de la conformation des chaînes de PtBA dans le DMF montre que cet intervalle de densités recouvre le régime crêpe au régime brosse. Le gonflement de brosses de PAA et la variation de la hauteur de la brosse L ont été étudiés en fonction de la densité de greffage, du pH et du sel ajouté cs (NaCl). Une transition brusque de collapsée à étirée est observée avec l’augmentation du pH, indépendamment de la densité de greffage. A pH neutre, les brosses sont collapsées et se comportent comme des brosses neutres en mauvais solvant. A pH basique, les brosses sont gonflées et chargées et se trouvent dans un régime de Pincus caractéristique des polyélectrolytes forts. En présence de sel, les charges sont partiellement écrantées et les répulsions électrostatiques dominent toujours dans la brosse. Cette étude contribue à une meilleure compréhension du comportement complexe des brosses de polyélectrolytes faibles et apporte un soutien expérimental à la théorie sur le comportement de ces brosses. / Neutral polymer brushes of poly(tert-butyl acrylate) (PtBA) and polyelectrolyte brushes of poly(acrylic acid) (PAA) were chemically grafted on mica in order to study their conformation as a function of grafting density, pH and ionic strength. The brushes were prepared via surface-initiated atom-transfer radical polymerization (SI-ATRP). This approach allows the control of the polymer growth and of the polymer grafting density. The study of brush conformation was investigated by measuring the dry and the swollen film thicknesses by Atomic Force microscopy (AFM) under various environmental conditions. Mica substrates were activated by a plasma method leading to OH-functionalized surfaces to which a radical initiator was covalently bound using standard siloxane protocols. The initiator grafting on the mica substrate was confirmed by water contact angle measurements and time-of-flight secondary ion mass spectrometry (TOF-SIMS). The covalently immobilized initiator successfully underwent SI-ATRP with tert-butyl acrylate, yielding end-grafted PtBA brushes that are covalently linked to mica. A linear relationship of the polymer thickness with respect to the molecular weight of the free polymer and with respect to the monomer conversion is obtained confirming that SI-ATRP is well controlled. The PtBA brushes were then hydrolyzed to PAA as confirmed by water contact angle measurements, polymer thickness measurements and FT-IR. The grafted layers show a good stability in air, organic solvent and aqueous solution and a reversible swelling. Film cleavage is observed for long exposure time in basic solution. This study represents the first example of chemically grafted brushes on mica via SI-ATRP. The polymer grafting density of poly(tert-butyl acrylate) was controlled by tuning the initiator surface coverage. By adjusting parameters such as the immobilization reaction time and concentration of the initiator, a wide range of initiator surface coverages and hence polymer densities on mica were possible ranging from 0.04 chain/nm2 to 0.5 chain/nm2). The swelling behavior of PAA brushes was investigated as a function of the polymer grafting density, pH and ionic strength cs (NaCl). A sharp transition from collapsed to stretched conformation was found with increasing pH. At neutral pH, the brushes are collapsed and behave like neutral brushes in poor solvent. At high pH, the brushes are swollen and charged and belong to the Pincus regime. In the presence of salt, the Coulombic repulsions are screened. The observed behavior of PAA brushes resembles the one of strong polyelectrolyte brushes. This study contributes to a better understanding of the complex behaviour of weak polyelectrolyte brushes and brings experimental support to theoretical studies.

Ce travail de thèse avait pour objectif d'élaborer un système vecteur ciblantl'endothélium pathologiquement activé dans les tissus enflammés, infectés ou tumoraux.Ce vecteur est sous forme de nanoparticules décorées de ligands glycosides capablesd'interagir avec l'E-sélectine, un récepteur exprimé sur les cellules endothélialesactivées.Nous avons mis au point une synthèse de copolymère amphiphile avec une architectureà bloc muni sur sa partie hydrophile d'un ligand glucidique. Ce copolymère a été par lasuite utilisé pour la préparation de nanoparticules de type coeur/couronne. La partiehydrophobe centrale est entourée d'une couronne hydrophile dont l'encombrementstérique et la mobilité limitent l'opsonisation de la particule. Le ciblage actif a été assurépar la présence d'un ligand du récepteur de l'E-sélectine aux extrémités des chaînes depolymères hydrophiles à la surface du vecteur.Avec ces nanoparticules dont les propriétés de surface sont prédéfinies, nous avonsmontré in vitro l'association efficace avec les cellules endothéliales activées, ce qui apermis de valider ce concept de ciblage moléculaire actif par l'intermédiaire du couplerécepteur/ ligand. Un tel système permettra d'améliorer l'indice thérapeutique et labiodistribution des principes actifs anti-inflammatoire et/ou anticancéreux.

With the emergence of novel and more effective drug therapies, increased importance is being placed upon the methods by which these drugs are being delivered to the body. In conventional drug delivery systems, there is very little control over the release of drug. The effective concentration at the target site can be achieved by intermittent administration of grossly excessive doses, which, often results in constantly, unpredictable variations in plasma concentrations, with the risk of reaching levels below or above the therapeutic range leading to marked side effects. A plethora of formulation strategies mainly based on polymeric/lipid nanoparticles, are described in literature. Even though these systems are therapeutically advantageous in comparison to conventional systems, they remain insensitive to the changing metabolic states of the body although the symptoms of most metabolic diseases follow a rhythmic pattern.A more appropriate and effective approach of managing some of these conditions lies in the chronotherapy. This approach allows for pulsed or self-regulated drug delivery which is adjusted to the staging of biological rhythms, since the onset of certain diseases exhibits strong circadian temporal dependence. In order to reach the objective of mimicking the biophysical and biochemical processes of pathological states, many innovations in material design for drug delivery systems (DDS) that are able to release the therapeutic payload-on-demand were done to release the therapeutic agent only when it is required, according to the physiological need. The development of multidisciplinary research teams has brought huge advantages in the design, fabrication and utilization of such smart systems, especially in the pharmaceutical field. Interestingly, numerous smart polymeric materials exhibit a response to a specific stimulus. A step further, the elaboration of purpose-built monomers can give rise to compounds with tunable sensitivities or multi-stimuli responsiveness. These smart polymers demonstrate an active responsiveness to environmental (or external) signals and change their physicochemical properties as designed (e.g. conformation, solubility, shape, charge or size). As far as the stimuli are concerned, they consist of physical (e.g. temperature, ultrasound, light, electricity, magnetic or mechanical stress), chemical (e.g. pH, ionic strength) and biological signals (e.g. enzymes, biomolecules). Due to the intrapersonal variabilities which may make internal stimuli hazardous, externally controlled systems rely on externally applied stimuli that are produced by stimuli-generating devices, which results in pulsed drug delivery. This type of delivery may be rapid and allows a transient release of a determined amount of drug within a short period of time immediately after a pre-determined off-release period. A novel strategy for the formation of multi-stimuli responsive materials endowed with pH, magnetic and light sensitivity was achieved. The approach relied on the incorporation of magnetic tetrahalogenoferrate(III) anions along a polymeric backbone based on poly(2-(N,N-dimethylamino) ethyl meth-acrylate) (PDMAEMA). Starting from the same PDMAEMA, quaternized pending amine groups with various halide derivatives gave rise to magnetic materials after anion metathesis. Measuring the magnetic susceptibility of these materials exhibited that the magnetic susceptibility increased as the substituted group size decreased (become smaller) which was apparently related to the steric hindrance around the ionic pendants. Additionally, a good correlation between the magnetic susceptibility and ferric content was found. Additional experimental and theoretical Raman analyses allowed the determination of the nature of the magnetic species constituting the materials. This strategy further offers the opportunity to tailor the magnetic response through partial ammonium salt formation. In order to merge the magnetic properties of ferric-based materials with another stimuli-responsive functionality, random copolymers containing DMAEMA (D) with diazobenzene (A) unit were prepared. So, three copolymers PDA were synthesized (with targeted D/A ratios 4/6 (PDA4), 6/4 (PDA6) and 8/2 (PDA8)). Meanwhile, different degrees of amine quaternization (10, 50 and 100 %) were applied, which led to the following polymeric salts PDAX/Y where X = 4, 6, 8 (referring to the percentage of the DMAEMA unit) and Y = 10, 50 and 100 (referring to the percentage of quaternized amine groups). Finally, the aforementioned materials were converted into magnetic polymers by anion exchange. As a result, magnetic responses correlated well with amount of iron oxide in these compounds and the amount of ionic pending groups along the backbone. Moreover, the remaining tertiary amines conferred pH sensitivity to the polymers whereas the diazobenzene units ensured light responsiveness through the well-established trans-to-cis isomerization.In order to functionalize these materials in the pharmaceutical field, an intelligent delivery system was prepared. Firstly, an attempt to formulate riboflavin-5’-phosphate sodium (RPS) loaded on PDA8 microspheres was made using double emulsion evaporation method. Meanwhile, prednisolone (PRD) microspheres were prepared using s/o/w emulsion technique. Subsequently, coating systems of cochineal red tablets were developed. These tablets were coated with polymer solution (using each of three types of copolymers: PDA8, PDA6, and PDA4) until the desired percentage of the coating was achieved (10, 15, and 20 % w/w). The cumulative release profiles of cochineal red tablets coated with PDA8, PDA6, and PDA4 showed a pH-sensitive release behavior. The release in the neutral media (pH ≈ 7.0) was very slow (less than 3 % after one hour). Then, after changing the pH to 1.2, an increase in the release of cochineal was observed. Furthermore, the cumulative release of cochineal red was at the highest value for the PDA8 and the lowest for PDA4 depending on the percentage of PDMAEMA moieties. Moreover, by increasing the percentage of the coating from (10, 15 to 20 % w/w), the cumulative release of cochineal decreased. Therefore, the copolymer PDAX can be used for controlling the release of drug by changing the pH value.Finally, the cochineal tablets coated with PDA6 (10 %) showed features of light sensitivity. The release of cochineal red from coated tablets was only due to the switching in the conformational trans/cis isomerization of azobenzene moieties upon irradiation, which was confirmed by comparing the release of coated tablets with uncoated tablets upon irradiation. / Doctorat en Sciences biomédicales et pharmaceutiques (Pharmacie) / info:eu-repo/semantics/nonPublished

Ce travail concerne la modification de surface de nanoparticules magnétiques (MNP) par des copolymères réactifs renfermant des cycles azlactone, aux fins de l’élaboration de nano-supports destinés à l’immobilisation de biomolécules. Trois stratégies basées sur des techniques de polymérisation radicalaire contrôlée ont été mises en œuvre.Dans la première, un copolymère poly(méthacrylate de poly(éthylène glycol)-stat-2-vinyl-4,4-diméthylazlactone) (poly(PEGMA-stat-VDM)) a été préparé par polymérisation radicalaire par transfert d’atome (ATRP) selon la technique « grafting from » à partir des MNP et utilisé pour la bioconjugaison de thymine peptide nucleic acid (PNA). La présence de l’écorce polymère et l’immobilisation du PNA ont été confirmées par différentes techniques complémentaires (FTIR, VSM).La deuxième stratégie est basée sur l’élaboration de MNP greffées pour la bioconjugaison de l’acide folique, via l’ARTP du PEGMA et de la VDM. L’analyse par microscopie électronique à transmission (TEM) a montré qu’après bioconjugaison les MNP possèdent une très bonne aptitude à la dispersion en milieu aqueux.La troisième stratégie met en œuvre la technique «grafting onto » de copolymères poly(oxyde d’éthylène)-bloc-poly(2-vinyl-4,4-dimethylazlactone) (PEO-b-PVDM) pour la préparation de nanosupports magnétiques recyclables. Des copolymères à blocs PEO-b-PVDM ont été préparés par la technique de polymérisation RAFT puis greffés sur des MNP fonctionnalisées amino-silane. Les analyses en TEM et par spectroscopie de corrélation de photons ont révélé l’aptitude à la dispersion aqueuse et à la formation de nanoclusters. Les clusters ainsi obtenus ont été utilisés en tant que nanosupports magnétiques recyclables pour l’adsorption d’anticorps. / We herein report the surface modification of magnetite nanoparticle (MNP) with copolymers containing active azlactone rings via a grafting ‘from’ and grafting ‘onto’ controlled radical polymerization (CRP) for use as a nano-solid support for immobilization with biomolecules. Three different approaches were presented as following. First, synthesis of poly(poly(ethylene glycol) methyl ether methacrylate-stat-2-vinyl-4,4-dimethylazlactone) (PEGMA-stat-VDM)-grafted MNP via a grafting ‘from’ atom transfer radical polymerization (ATRP) and its application as a platform for conjugating thymine peptide nucleic acid (PNA) monomer were presented. The presence of polymeric shell and the immobilization of thymine PNA on MNP core were confirmed by fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometry (VSM) techniques. The second strategy is based on the synthesis of MNP grafted with PEGMA and VDM via ATRP for conjugation with folic acid (FA). The existence of PEGMA and VDM in the structure was characterized by FTIR, TGA and VSM. After the FA conjugation, Transmission Electron Microscopy (TEM) results indicated that the FA-conjugated MNP having high VDM content exhibited good dispersibility in water.Third, the synthesis of MNP grafted with poly(ethylene oxide)-block-poly(2-vinyl-4,4-dimethylazlactone) (PEO-b-PVDM) block copolymer via a grafting ‘onto’ strategy and its application as recyclable magnetic nano-support for adsorption with antibody were studied. PEO-b-PVDM diblock copolymers were first synthesized using reversible addition-fragmentation chain transfer (RAFT) polymerization and then grafted onto amino-functionalized MNP. TEM images and photo correlation spectroscopy (PCS) indicated an improvement in the particle dispersibility in water after coating with the copolymers. The nanoclusters with PEO-b-PVDM copolymer coating were used as recyclable magnetic nano-supports for adsorption with antibody.

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