This thesis work focused on polymer modification of silicon surface to improve its resistance to protein adsorption. Surface modification was achieved through surface-initiated atom transfer radical polymerization (SI-ATRP) grafting of poly(N,N-dimethyl amino) ethyl methacrylate (PDMAEMA). Since PDMAEMA is CO2-responsive, CO2 cleaning of the modified surface was also investigated. SI-ATRP was chosen to graft PDMAEMA brushes on silicon surface for high graft densities and its good control of polymer molecular weight and polydispersity. Surface characterization of PDMAEMA-modified silicon surfaces included hydrophilicity, layer thickness and surface chemical elemental composition. Protein adsorption experiments were carried out to evaluate the protein resistance of the modified surfaces. Albumin adsorption from single protein solution, as well as from human plasma, decreased significantly after PDMAEMA grafting, and the adsorbed amount decreased with increasing polymer chain length. The maximum decrease in adsorption of 90% relative to the unmodified silicon, was reached at a graft layer thickness of 40 nm (measured in the dry state). Protein resistance in plasma showed PDMAEMA -modified silicon provided significant resistance to most of the tested proteins. Compared to the PEO-modified surface, the PDMAEMA surface showed much greater resistance to albumin adsorption, but, surprisingly, it adsorbed relatively large amounts of vitronectin and prothrombin. Vitronectin may have been degraded in contact with PDMAEMA-modified surface. Also, it was the only surface out of the four, which adsorbed significant amounts of prothrombin. These unexpected observations indicate further investigation will be required to fully assess the protein-resistant properties of these PDMAEMA surfaces. CO2-induced protein desorption was also studied. Cleaning experiments were performed by bubbling CO2 into vials containing the protein-adsorbed PDMAEMA-modified surface after 2 h protein solution exposure. Radiolabelling of albumin showed that the CO2 cleaning effectiveness was related with the PDMAEMA thickness. It was found that a surface with graft thickness 20 nm (dry) responded more strongly to CO2 than one with 15 nm thickness. Western blotting results confirmed that CO2 contributed to protein desorption from the PDMAEMA surface. / Thesis / Master of Applied Science (MASc)

Copolímeros, macromoléculas orgânicas ou inorgânicas com alta massa molar, consistem de unidades monômericas repetidas, unidas por ligações covalentes e que apresentam mais de um tipo de monômero. Neste trabalho estudamos três copolímeros constituídos por dois blocos distintos, isto é copolímeros dibloco, onde um dos blocos é constituído pelo polimetacrilato de metila, PMMA e o outro pelo polimetacrilato de N,N dimetilamino, PDMAEMA, e o homopolímero de PDMAEMA. A fórmula geral dos copolímeros dibloco estudados é PMMAm-b-PDMAEMAn onde o número de monômeros de cada bloco é representado pelos índices m e n. Os copolímeros PMMA1-b-PDMAEMA6,3 (MM, 54.200), PMMA1-b-PDMAEMA3,0 (MM 27.558), o PMMA1-b-PDMAEMA1,1 (MM 25.555) e o homopolímero PDMAEMA (MM 41.614,9) tiveram suas massas molares e a razão entre os monômeros de cada bloco caracterizados por cromatografia de gel permeação, GPC, e NMR. Determinamos a concentração micelar crítica (CMC) dos copolímeros e verificamos, por RMN e fluorescência, o efeito da concentração e do pH na sua agregação. A interação dos copolímeros com vesículas unilamelares grandes, LUVs, preparadas com misturas de fosfatidilcolina, PC, e fosfatidilglicerol, PG, foi estudada em diferentes condições de pH e força iônica. A interação dos polímeros com as LUVs também foi estudada medindo-se o diâmetro hidrodinâmico e potencial zeta das LUVs na presença dos polímeros. Observou-se que, quando a razão polímero/lipídio é alta, os polímeros se ligam às LUVs, neutralizando completamente a carga das vesículas. Quando a concentração de LUVs é próxima à dos polímeros, forma-se uma rede que conduz à agregação e precipitação dos complexos. Estudamos o efeito dos polímeros na permeabilização de LUVs e vesículas unilamelares gigantes (GUVs) preparadas com misturas de PC:PG. Os copolímeros permeabilizaram as LUVs, dependendo da razão polímero/lipídio, do pH, força iônica e das características hidrofóbicas e hidrofílicas de cada copolímero. Quanto maior a porcentagem de PG nas LUVs maior a interação com os copolímeros. A ligação dos copolímeros às LUVs deve produzir segregação dos fosfolipídios negativos na bicamada das LUVs (i.e., separação lateral de fases) facilitando a permeabilização das vesículas. Demonstramos que os copolímeros se ligam à superfície das GUVs modificando a sua forma e levando ao rompimento das vesículas. Estes efeitos foram modulados pelo pH e a força iônica do meio. O efeito de permeabilização dos copolímeros foi correlacionado com as razões entre os blocos hidrofóbicos e hidrofílicos. Quando o copolímero tem uma maior fração de PDMAEMA, o bloco mais hidrofílico do copolímero, este efeito é mais evidente. A porcentagem de permeabilização, após um tempo definido, para copolímeros de mesma massa molar, como o PMMA1-b-PDMAEMA3,0 (MM 27.558) e o PMMA1-b-PDMAEMA1,1 (MM 25.555), é muito maior com o copolímero com maior porção hidrofílica, o PMMA1-b-PDMAEMA3,0. O homopolímero DMAEMA também se mostrou eficiente na interação com as LUVs, porém menos que o PMMA1-b-PDMAEMA6,3.que possui maior numero de unidades DMAEMA e uma sequencia de monômeros de MMA. Demonstramos, nesta Tese, que o efeito de copolímeros sintéticos contendo regiões hidrofóbicas e hidrofílicas são bons modelos de peptídeos e proteínas permitindo avaliar quantitativamente o efeito dessas interações em modelos de membranas. / Copolymers are organic or inorganic macromolecules with high molecular weight, consisting of repeated monomer units joined by covalent bonds and exhibit more than one type of monomer. Here, we studied three copolymers consisting of two different blocks, i.e. diblock copolymers, where one block is constituted by methyl polymethacrylate, PMMA and other by polymethacrylate N, N-dimethylamino, PDMAEMA and a homopolymer PDMAEMA. The general formula of the diblock copolymers studied was PMMAm-b-PDMAEMAn where the number of monomers of each block is represented by indexes m and n. The PMMA1-b-PDMAEMA6,3 copolymers (MW, 54,200), PMMA1 PDMAEMA3,0-b (MW 27,558), the PMMA1 PDMAEMA1,1-b (MW 25,555) and PDMAEMA homopolymer (MW 41614.9) had their molecular weights and the ratio between the monomers of each block characterized by gel permeation chromatography, GPC, and NMR. The critical micelle concentration (CMC) of the copolymers was determined by fluorescence and the aggregation of the copolymers verified by NMR. The effect pH on the copolymers CMC was also determined. The interaction of copolymers with large unilamellar vesicles, LUV, prepared with mixtures of phosphatidylcholine, PC, and phosphatidylglycerol, PG, was studied under different conditions of pH and ionic strength. The interaction of the polymers with the LUVs was also studied measuring the hydrodynamic diameter and zeta potential of the LUVs in the presence of the polymers. It was observed that when the ratios polymer / lipid are high, the polymers bind to the LUVs, completely neutralizing the charge of the vesicles. When the concentration of LUVs is close to that of the polymers, it forms a network that leads to aggregation and precipitation of the complexes. We studied the effect of polymers in permeabilization LUVs and giant unilamellar vesicles (GUVs) prepared with PC:PG. The copolymers permeabilized the LUVs, depending on the ratio polymer / lipid, pH, ionic strength and the hydrophobic and hydrophilic characteristics of each copolymer. The higher the percentage PG LUVs lead to greater interaction with the copolymers. The binding of the copolymers to the LUVs with negative charge induced phase separation of phospholipids in the bilayer of LUVs (ie, lateral phase separation) facilitating the permeability of the vesicles. We demonstrate that copolymers bind to the surface of GUVs changing its shape and leading to rupture of vesicles. These effects are modulated by pH and ionic strength of the media. The permeabilization effect of the copolymers was correlated with the ratios of the hydrophobic and hydrophilic blocks. When the copolymer has a larger fraction of PDMAEMA, the more hydrophilic block copolymer, this effect is more evident. The percentage of permeabilization, after a set time, for the same molar mass copolymers such as b-PDMAEMA3,0 PMMA1 (MW 27,558) and PMMA1 PDMAEMA1,1-b (MW 25,555), is much more efficient with copolymer with greater hydrophilic portion, the b-PMMA1 PDMAEMA3,0. The DMAEMA homopolymer also proved efficient in interacting with the LUVs. We demonstrated that synthetic copolymers containing hydrophobic and hydrophilic regions are good models of peptides and proteins allowing quantitatively evaluate the effects of these interactions on model membranes

Copolímeros, macromoléculas orgânicas ou inorgânicas com alta massa molar, consistem de unidades monômericas repetidas, unidas por ligações covalentes e que apresentam mais de um tipo de monômero. Neste trabalho estudamos três copolímeros constituídos por dois blocos distintos, isto é copolímeros dibloco, onde um dos blocos é constituído pelo polimetacrilato de metila, PMMA e o outro pelo polimetacrilato de N,N dimetilamino, PDMAEMA, e o homopolímero de PDMAEMA. A fórmula geral dos copolímeros dibloco estudados é PMMAm-b-PDMAEMAn onde o número de monômeros de cada bloco é representado pelos índices m e n. Os copolímeros PMMA1-b-PDMAEMA6,3 (MM, 54.200), PMMA1-b-PDMAEMA3,0 (MM 27.558), o PMMA1-b-PDMAEMA1,1 (MM 25.555) e o homopolímero PDMAEMA (MM 41.614,9) tiveram suas massas molares e a razão entre os monômeros de cada bloco caracterizados por cromatografia de gel permeação, GPC, e NMR. Determinamos a concentração micelar crítica (CMC) dos copolímeros e verificamos, por RMN e fluorescência, o efeito da concentração e do pH na sua agregação. A interação dos copolímeros com vesículas unilamelares grandes, LUVs, preparadas com misturas de fosfatidilcolina, PC, e fosfatidilglicerol, PG, foi estudada em diferentes condições de pH e força iônica. A interação dos polímeros com as LUVs também foi estudada medindo-se o diâmetro hidrodinâmico e potencial zeta das LUVs na presença dos polímeros. Observou-se que, quando a razão polímero/lipídio é alta, os polímeros se ligam às LUVs, neutralizando completamente a carga das vesículas. Quando a concentração de LUVs é próxima à dos polímeros, forma-se uma rede que conduz à agregação e precipitação dos complexos. Estudamos o efeito dos polímeros na permeabilização de LUVs e vesículas unilamelares gigantes (GUVs) preparadas com misturas de PC:PG. Os copolímeros permeabilizaram as LUVs, dependendo da razão polímero/lipídio, do pH, força iônica e das características hidrofóbicas e hidrofílicas de cada copolímero. Quanto maior a porcentagem de PG nas LUVs maior a interação com os copolímeros. A ligação dos copolímeros às LUVs deve produzir segregação dos fosfolipídios negativos na bicamada das LUVs (i.e., separação lateral de fases) facilitando a permeabilização das vesículas. Demonstramos que os copolímeros se ligam à superfície das GUVs modificando a sua forma e levando ao rompimento das vesículas. Estes efeitos foram modulados pelo pH e a força iônica do meio. O efeito de permeabilização dos copolímeros foi correlacionado com as razões entre os blocos hidrofóbicos e hidrofílicos. Quando o copolímero tem uma maior fração de PDMAEMA, o bloco mais hidrofílico do copolímero, este efeito é mais evidente. A porcentagem de permeabilização, após um tempo definido, para copolímeros de mesma massa molar, como o PMMA1-b-PDMAEMA3,0 (MM 27.558) e o PMMA1-b-PDMAEMA1,1 (MM 25.555), é muito maior com o copolímero com maior porção hidrofílica, o PMMA1-b-PDMAEMA3,0. O homopolímero DMAEMA também se mostrou eficiente na interação com as LUVs, porém menos que o PMMA1-b-PDMAEMA6,3.que possui maior numero de unidades DMAEMA e uma sequencia de monômeros de MMA. Demonstramos, nesta Tese, que o efeito de copolímeros sintéticos contendo regiões hidrofóbicas e hidrofílicas são bons modelos de peptídeos e proteínas permitindo avaliar quantitativamente o efeito dessas interações em modelos de membranas. / Copolymers are organic or inorganic macromolecules with high molecular weight, consisting of repeated monomer units joined by covalent bonds and exhibit more than one type of monomer. Here, we studied three copolymers consisting of two different blocks, i.e. diblock copolymers, where one block is constituted by methyl polymethacrylate, PMMA and other by polymethacrylate N, N-dimethylamino, PDMAEMA and a homopolymer PDMAEMA. The general formula of the diblock copolymers studied was PMMAm-b-PDMAEMAn where the number of monomers of each block is represented by indexes m and n. The PMMA1-b-PDMAEMA6,3 copolymers (MW, 54,200), PMMA1 PDMAEMA3,0-b (MW 27,558), the PMMA1 PDMAEMA1,1-b (MW 25,555) and PDMAEMA homopolymer (MW 41614.9) had their molecular weights and the ratio between the monomers of each block characterized by gel permeation chromatography, GPC, and NMR. The critical micelle concentration (CMC) of the copolymers was determined by fluorescence and the aggregation of the copolymers verified by NMR. The effect pH on the copolymers CMC was also determined. The interaction of copolymers with large unilamellar vesicles, LUV, prepared with mixtures of phosphatidylcholine, PC, and phosphatidylglycerol, PG, was studied under different conditions of pH and ionic strength. The interaction of the polymers with the LUVs was also studied measuring the hydrodynamic diameter and zeta potential of the LUVs in the presence of the polymers. It was observed that when the ratios polymer / lipid are high, the polymers bind to the LUVs, completely neutralizing the charge of the vesicles. When the concentration of LUVs is close to that of the polymers, it forms a network that leads to aggregation and precipitation of the complexes. We studied the effect of polymers in permeabilization LUVs and giant unilamellar vesicles (GUVs) prepared with PC:PG. The copolymers permeabilized the LUVs, depending on the ratio polymer / lipid, pH, ionic strength and the hydrophobic and hydrophilic characteristics of each copolymer. The higher the percentage PG LUVs lead to greater interaction with the copolymers. The binding of the copolymers to the LUVs with negative charge induced phase separation of phospholipids in the bilayer of LUVs (ie, lateral phase separation) facilitating the permeability of the vesicles. We demonstrate that copolymers bind to the surface of GUVs changing its shape and leading to rupture of vesicles. These effects are modulated by pH and ionic strength of the media. The permeabilization effect of the copolymers was correlated with the ratios of the hydrophobic and hydrophilic blocks. When the copolymer has a larger fraction of PDMAEMA, the more hydrophilic block copolymer, this effect is more evident. The percentage of permeabilization, after a set time, for the same molar mass copolymers such as b-PDMAEMA3,0 PMMA1 (MW 27,558) and PMMA1 PDMAEMA1,1-b (MW 25,555), is much more efficient with copolymer with greater hydrophilic portion, the b-PMMA1 PDMAEMA3,0. The DMAEMA homopolymer also proved efficient in interacting with the LUVs. We demonstrated that synthetic copolymers containing hydrophobic and hydrophilic regions are good models of peptides and proteins allowing quantitatively evaluate the effects of these interactions on model membranes

No description available.

Dans ce travail, nous nous sommes intéressés aux émulsions stabilisées par une famille de copolymères diblocs biocompatibles polydiméthylsiloxane-b-poly(méthacrylate de diméthylaminoéthyle) (PDMS-b-PDMAEMA). Le bloc PDMAEMA, porteur de fonctions amines, est sensible au pH et à la force ionique. En faisant varier ces deux paramètres, des émulsions directes, inverses et multiples E/H/E ont pu être obtenues en une seule étape d’émulsification, par cisaillement d’une phase aqueuse et d’une phase huile biocompatible (Miglyol® 812 ou myristate d’isopropyle). Pour un copolymère présentant des longueurs de blocs hydrophile et hydrophobe similaires, le PDMS60-b-PDMAEMA50, des émulsions multiples stables sur plus de deux ans sont obtenues avec les deux huiles, pour des pH proches du pKa du PDMAEMA et dans une vaste gamme de sel ajouté. Il a en outre été établi sur des cellules intestinales humaines que les émulsions formées à partir de ces copolymères ne présentent pas de cytotoxicité et peuvent être utilisées pour développer des applications pour l’homme.La diminution du pH de la phase aqueuse conduit à la déstabilisation des émulsions doubles en émulsions directes, permettant d’obtenir la libération contrôlée des espèces encapsulées dans les gouttelettes d’eau internes. Des essais d’encapsulation ont été réalisés avec une molécule modèle, le saccharose, et un antioxydant naturellement présent dans le thé vert, la catéchine, molécule fragile facilement dégradée. Ces molécules peuvent être libérées à loisir par diminution du pH et déstabilisation de l’émulsion multiple, la formation de liaisons hydrogènes entre les molécules encapsulées et le copolymère limitant cependant le relargage. Il a également été démontré que les émulsions ont un effet protecteur sur la catéchine lors du stockage et permettent d’exalter son pouvoir antioxydant.Enfin, nous avons étudié la formation d’émulsions stabilisées par le PDMS-b-PDMAEMA par voie microfluidique. Une méthode originale a été développée pour permettre de former de façon simple des émulsions doubles sur des puces en PDMS. Des émulsions E/H/E ont été obtenues dans des conditions de pH et de force ionique bien précises, et la catéchine a pu également être encapsulée au cœur des gouttelettes internes par cette méthode. / In this work, we studied different kinds of emulsions stabilized by biocompatible diblock copolymers polydimethylsiloxane-b-poly(dimethylaminoethyle methacrylate) (PDMS-b-PDMAEMA). PDMAEMA is sensitive to pH and ionic strength thanks to the amine groups carried by the chain. Varying the latter parameters, we obtained direct, inverse and W/O/W double emulsions in only one emulsification step, by shearing an aqueous phase and a biocompatible oil (Miglyol® 812 or isopropyle myristate). For a copolymer having hydrophilic and hydrophobic blocks of similar lengths, PDMS60-b-PDMAEMA50, very stable multiple emulsions (more than two years) were obtained, for pH close to pKa of PDMAMEA and in a large range of salt concentrations. Cytotoxicity measurements were performed on intestinal human cells, proving the possibility of using the emulsions stabilized with these copolymers to develop applications for health care.pH lowering allows to turn direct emulsions to multiple ones, leading to the controlled release of encapsulated species in the inner water drops. Encapsulation tests have been carried out with a model molecule, sucrose, and with an antioxidant extracted from green tea, catechin. Both molecules could be released from our emulsions by reducing the pH, despite the formation of hydrogen bonds between the encapsulated compounds and the copolymer which prevented complete deliverance. We demonstrated the ability of our multiple emulsions to protect the fragile catechin molecule during storage and preserve its antioxidant capacity.Additionally, we achieved the formation of PDMS-b-PDMAEMA stabilized emulsions by microfluidics. An innovative method was developed to allow the formation of double emulsions on PDMS microchips in an easy way. W/O/W emulsions were obtained for precise pH and salt concentrations, and catechin could also be successfully encapsulated in the internal water droplets by this method.

Les surfaces de polymères électro-stimulables font partie de la catégorie des surfacesintelligentes. Elles sont capables de modifier leurs propriétés lorsqu’elles sont stimulées par unchamp électrique. Au cours de cette thèse nous avons fabriqué des surfaces de chaines depolyélectrolytes faibles greffées (PAA, P2VP, PDMAEMA), soit par auto-assemblage, soit partransfert via la balance de Langmuir. Nous avons ensuite étudié l’organisation des chaines depolyélectrolytes à la surface en fonction des conditions de pH et de sel de la sous-phase dans labalance de Langmuir. Avant de stimuler ces chaines de polyélectrolytes greffées à l’aide d’unchamp électrique, nous avons étudié leur sensibilité à la variation de pH et à la variation de laconcentration en sel. Pour cela des mesures d’épaisseurs de films de polyélectrolytes et desmesures d’angle de contact ont été effectuées. Ces études préliminaires nous ont permis desélectionner des valeurs de densité de greffage des chaines de polyélectrolytes ainsi que le pH etla concentration en sel de la solution adaptés pour la stimulation des surfaces par un champélectrique. Nous avons alors montré que les chaines greffées de PAA et de PDMAEMA étaienttrès sensibles à la variation de la tension électrique lorsque le pH est proche du pKa ou du pKb dela surface : pour une charge de la surface identique aux charges des chaines de polyélectrolytes,ces dernières vont adopter une conformation de brosse tandis qu’elles seront collapsées lorsque lacharge de la surface est de signe opposé aux charges des chaines. Cette transition réversible deschaines en fonction de la valeur de la tension appliquée permet de contrôler les propriétés demouillage et d’adhésion de ces surfaces. En revanche, pour un pH proche du pKb, les chainesgreffées de P2VP sont peu sensibles à l’application d’un champ électrique. Nous avons supposéque cela était dû à une variation de pH local au sein des chaines lorsque le champ électrique estappliqué. / Electro-responsive polymer surfaces are able to change their properties when they are stimulatedby an electric field. In this work, we grafted weak polyelectrolyte on surfaces by self-assembly orby transferring the molecules using the Langmuir-Schaefer method. First we studied theorganization of the polyelectrolyte chains at the surface for different pH and salt concentration ofthe subphase used in the Langmuir trough. Then we explored the response of the surfaces to pHand salt concentration changes by measuring the thickness variation of the polyelectrolyte filmsand the changes in contact angle. These preliminary studies allowed us to select the graftingdensity of polyelectrolyte chains and the pH and salt concentrations of the aqueous solutionadapted for the stimulation of the surfaces by an electric field. We then demonstrated that PAAand PDMAEMA grafted chains were very sensitive to the variation of the applied voltage whenthe pH is close to the pKa or from the pKb of the surface. If the charge of the surface has the samesign as the charges on the polyelectrolyte chains, the latter would adopt a brush conformation,whereas if the charge of the surface has the opposite sign compared to the sign of the charges onthe polyelectrolyte chains, the chains would collapse. This reversible transition of the chainsconformation with the sign of the applied voltage allowed us to control the wetting and theadhesion properties of these surfaces. Nevertheless, for a pH close to the pKb, the P2VP graftedchains are almost unresponsive to the application of an electric field. We supposed that this is theconsequence of a local pH variation inside the grafted chains when the electric field is applied.

Verankerte Polymere können die Funktionalität einer Oberfläche beeinflussen. Der Schwerpunkt dieser Arbeit liegt auf der Untersuchung von Polymerbürsten aus Polyacrylsäure (PAA) und Poly(N,N-dimethylaminoethyl methacrylat) (PDMAEMA). Auf Oberflächen, die mit PAA Bürsten beschichtet sind, können Proteine im nativen Zustand immobilisiert werden. Für PDMAEMA ist eine Reaktion auf externe Reize bekannt. So kann dessen untere kritische Lösungstemperatur (LCST) zur Einstellung der Hydrophobizität von Oberflächen verwendet werden. Erstmalig im Rahmen dieser Arbeit wurde untersucht, wie sich hydrostatischer Druck von bis zu 1000 bar auf die Funktionalität der verwendeten Polymerbürsten auswirkt. Aus Diblock-Kopolymeren wurden Langmuir-Filme unterschiedlicher Ankerdichte mit der Langmuir-Schäfer Technik auf feste Substrate übertragen. Die Funktionalität der PAA Bürsten wurde vor und nach der Adsorption von Rinderserumalbumin (BSA) in gepufferter D2O-Lösung mit Hilfe der Neutronenreflektometrie (NR) bei 1 bar und 900 bar an der fest-flüssig Grenzfläche untersucht. Es wurden Volumenfraktionsprofile der PAA Bürste und adsorbierten BSA extrahiert, woraus sich eine lineare Abhängigkeit zwischen Ankerdichte und Menge an adsorbiertem Protein feststellen ließ. Erhöhung des hydrostatischen Druckes auf 900 bar veränderte weder die PAA Volumenprofile noch die Immobilisierung von BSA. Die PDMAEMA Bürsten wurden mittels NR bei Temperaturen von 20-60 °C und Drücken von 1-1000 bar untersucht. Zur Analyse der Daten wurde ein neuartiges Dichteprofil-Modell verwendet. Temperaturerhöhung führt zur stetigen Abnahme der Bürstendicke. Dies lässt sich durch den LCST induzierten Phasenübergang der Polymere vom hydrophilen in einen hydrophoben Zustand erklären. Es wurde gefunden, dass eine Erhöhung des hydrostatischen Druckes diesem Prozess entgegenwirkt. Strukturänderungen der Polymerbürsten bei Erhöhung der Temperatur um 10 K ließen sich durch Erhöhung des Druckes um 1000 bar rückgängig machen. / The functionality of an interface can be modified by polymer brushes. The focus of this work is on brushes of either polyacrylic acid (PAA) or poly(N,N-dimethylaminoethyl methacrylate) (PDMAEMA). PAA brushes provide a soft interface that prevents the denaturation of adsorbed proteins. PDMAEMA is known to respond to external stimuli. The lower critical solution temperature (LCST) of PDMAEMA can be used to tune the hydrophobicity of the interface with temperature. For the first time, the effect of elevated hydrostatic pressure, up to 1000 bar, on the functionality of these systems is investigated. Planar PAA and PDMAEMA brushes are prepared from precursor diblock copolymer Langmuir layers with varied grafting density utilizing the Langmuir-Schäfer transfer technique. For solvent-swollen PAA brushes, neutron reflectivity (NR) measurements are conducted at the solid-liquid interface after incubation in buffered D2O and after the adsorption of bovine serum albumin (BSA) from the aqueous liquid phase at 1 bar and 900 bar. Detailed volume fraction profiles of the PAA brush and adsorbed BSA proteins are extracted. The amount of adsorbed BSA is found to scale linearly with grafting density. An elevated hydrostatic pressure of 900 bar is found to have no impact on the structure of the PAA brush and its capability to bind BSA proteins. The PDMAEMA brushes are investigated by NR at the solid-liquid interface in a temperature range of 20 to 60 °C for hydrostatic pressures from 1 to 1000 bar. A novel theoretical model of the brush density profile is used to fit the experimental NR data. Increasing the temperature causes a continuous decrease of the polymer brush thickness due to a hydrophobic coil to globule transition of the polymer chains when crossing the LCST. Hydrostatic pressure is found to act antagonistic to temperature. The hydrophobic collapse of the PDMAEMA brush caused by a temperature increase of 10 K is counterbalanced by a pressure increase of 1000 bar.