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In this work the two experimental dental implant materials FAT and FAW, made of fluoroapatite particles embedded in polymer matrices, and films of the proteins lysozyme, amylase and bovine serum albumin (BSA), adsorbed to the two dental implant materials, were investigated with time-of-flight secondary ion mass spectrometry (ToF-SIMS) and the multivariate data analysis technique discriminant principal component analysis (DPCA).

<p>The objective of this thesis was to investigate and characterize the interaction between blood proteins and different surfaces with emphasis on protein adsorption to bioceramics and model surfaces. Special effort was made to monitor the spontaneous and selective adsorption of proteins from human plasma and to examine the orientation, conformation and functional behavior of single proteins after adsorption. </p><p>Five different ceramic biomaterials: alumina (Al₂O₃), zirconia (ZrO₂), hydroxyapatite (Ca₁₀(PO₄)₆(OH)₂) and two glass-ceramics, AP40 (SiO₂-CaO-Na₂O-P₂O₅-MgO-K₂O-CaF₂) and RKKP (AP40 with Ta₂O₃-La₂O₃), were exposed to human plasma and their protein binding capacities and affinities for specific proteins were studied by chromatography, protein assays, two-dimensional gel electrophoresis and Western blotting. The studies showed that all materials adsorbed approximately the same high amount of plasma proteins and that they therefore should be fully covered by proteins in an <i>in vivo</i> setting. The adsorbed proteins were different for most materials which could explain their previously observed different levels of tissue integration <i>in vivo</i>. </p><p>Four of the proteins that behaved differently, ceruloplasmin, prothrombin, α₂-HS-glycoprotein and α₁-antichymotrypsin, were selected for characterization with atomic force microscopy and ellipsometry. The studies, which were performed on ultraflat silicon wafers (silica), showed that the proteins oriented themselves with their long axis parallel to the surface or as in case of ceruloplasmin with one of its larger sides towards the surface. All of them had globular shapes but other conformational details were not resolved. Furthermore, prothrombin (none of the others) formed multilayers at high proteins concentrations. </p><p>The functional behaviour of the adsorbed proteins, referring to their cell binding and cell spreading capacity on silica and a positive cell adhesion reference surface (Thermanox®), was affected by the underlying substrate. Ceruloplasmin, α₂-HS-glycoprotein and α₁-antichymotrypsin stimulated cell attachment to silica, but suppressed attachment to Thermanox®. Prothrombin stimulated cell attachment to both surfaces. The attachment was in most cases mediated both by cell membrane-receptors (integrins) and by non-specific interactions between the cell and the material. </p><p>This thesis showed that the compositional mixture, orientation, conformation and functional behavior of the adsorbed proteins are determined by the properties of the underlying surface and if these parameters are controlled very different cellular responses can be induced.</p>

The objective of this thesis was to investigate and characterize the interaction between blood proteins and different surfaces with emphasis on protein adsorption to bioceramics and model surfaces. Special effort was made to monitor the spontaneous and selective adsorption of proteins from human plasma and to examine the orientation, conformation and functional behavior of single proteins after adsorption. Five different ceramic biomaterials: alumina (Al2O3), zirconia (ZrO2), hydroxyapatite (Ca10(PO4)6(OH)2) and two glass-ceramics, AP40 (SiO2-CaO-Na2O-P2O5-MgO-K2O-CaF2) and RKKP (AP40 with Ta2O3-La2O3), were exposed to human plasma and their protein binding capacities and affinities for specific proteins were studied by chromatography, protein assays, two-dimensional gel electrophoresis and Western blotting. The studies showed that all materials adsorbed approximately the same high amount of plasma proteins and that they therefore should be fully covered by proteins in an in vivo setting. The adsorbed proteins were different for most materials which could explain their previously observed different levels of tissue integration in vivo. Four of the proteins that behaved differently, ceruloplasmin, prothrombin, α2-HS-glycoprotein and α1-antichymotrypsin, were selected for characterization with atomic force microscopy and ellipsometry. The studies, which were performed on ultraflat silicon wafers (silica), showed that the proteins oriented themselves with their long axis parallel to the surface or as in case of ceruloplasmin with one of its larger sides towards the surface. All of them had globular shapes but other conformational details were not resolved. Furthermore, prothrombin (none of the others) formed multilayers at high proteins concentrations. The functional behaviour of the adsorbed proteins, referring to their cell binding and cell spreading capacity on silica and a positive cell adhesion reference surface (Thermanox®), was affected by the underlying substrate. Ceruloplasmin, α2-HS-glycoprotein and α1-antichymotrypsin stimulated cell attachment to silica, but suppressed attachment to Thermanox®. Prothrombin stimulated cell attachment to both surfaces. The attachment was in most cases mediated both by cell membrane-receptors (integrins) and by non-specific interactions between the cell and the material. This thesis showed that the compositional mixture, orientation, conformation and functional behavior of the adsorbed proteins are determined by the properties of the underlying surface and if these parameters are controlled very different cellular responses can be induced.

Owing to their key role in mucosal functioning as surface barriers with biospecific interaction potentials, the mucins are interesting candidates for use as surface modifiers in biomaterials applications. In this work, “mild” fractionation procedures were used to prepare mucins of bovine (BSM), porcine (PGM), and human (MG1) origin. Biophysicochemical analysis showed the prepared mucins to differ in size, charge, conformation, and composition. In turn, these factors were shown to govern mucin adsorption on hydrophilic and hydrophobic model surfaces. To enable for detailed coating analysis, methods for the qualitative and quantitative analysis of mucin-based coatings were developed. Of particular interest, a method for the determination of the fraction of surface-exposed, presumed bioactive proteins in a complex mucin coating was described. It was shown, using microscopy and activation assays, that mucin precoating effectively suppresses the neutrophil response towards a polymeric model biomaterial. Under optimal coating conditions, all mucins performed equally well, thus indicating them to be functionally similar. Coating analysis suggested that efficient mucin surface-shielding is critical for good mucin coating performance. Following a study on the complexation of albumin with preadsorbed mucin, we investigated the effect of mucin precoating on the conformation and neutrophil-activating properties of adsorbed host proteins. We found that mucin precoating greatly reduces the strong immune-response normally caused by adsorbed proinflammatory proteins (IgG and sIgA). Detailed coating analysis revealed that the fraction of surface-exposed protein in the mucin-protein composite influences the neutrophil response. Unexpectedly low neutrophil activation for composites containing near-monolayer concentrations of exposed IgG, suggested IgG to act synergistically with mucin on the surface. Conformational analysis supported this by showing that a preadsorbed mucin layer could stabilize adsorbed IgG through complexation. Our findings link well to the complex in vivo situation and suggest that functional mucosal mimics can be created in situ for improved biomaterials performance.

The increasing demands for biopharmaceuticals to treat different diseases have raised concerns about controlling the quality and efficacy of such pharmaceuticals. The design and formulation of a stable protein or peptide based biopharmaceutical runs into the limitation that at high concentrations (> 100 mg/ml) or during long storage process the drug undergoes aggregation. During synthesis, purification, storage or packaging of these drugs different kinds of stresses like chemical, oxidative, thermal, shear, etc. are encountered. These stresses promote the non-native aggregation of protein and peptide based drugs. Injection or administration of such drugs if contaminated with aggregates causes patient discomfort or development of an antibody which can adversely affect patient’s conditions. This brings out the necessity of finding a way so that such aggregation is avoided. Nanoparticles have been used as vehicles for drug delivery and diagnostic agents in biology for a while. The surface of the nanoparticles is known to adsorb small as well as large molecules with different kinetics and energetics of interaction. I have used nanoparticles to adsorb proteins to protect them against aggregation when they are subjected to denaturing conditions. The effectiveness of the nanoparticles in stopping protein aggregation, recovery of the proteins and reversibility of the adsorption process, the catalytic activity of the proteins before and after adsorption on the surface have all been studied in details. The work described here has been divided in 8 chapters and the contents of each chapter are described below. In Chapter 1 I have provided a brief introduction to the protein aggregation problem. The motivation and scope of the current work has been presented in this chapter. Materials and methods have been described in Chapter 2. Synthesis of gold and silica nanoparticles, their characterization and stability under experimental conditions have been illustrated in this chapter. The spectroscopic assays and techniques which I have used to study the effect of gold and silica nanoparticles on protein aggregation have been discussed at lengths in this chapter. In Chapter 3 I have demonstrated the effect of gold nanoparticles on thermal aggregation of alcohol dehydrogenase (ADH). The size of the nanoparticle was varied in the range of 15-60 nm and the effect was measured by various spectroscopic assays and techniques. I have observed that gold nanoparticles prevent thermal aggregation of ADH and the efficiency is high. Gold nanoparticles in nanomolar or even picomolar concentrations are capable of preventing the aggregation of ADH at micromolar concentrations. In Chapter 4 the role of gold nanoparticles as suppressor of protein aggregation was extended to another protein, insulin. Chemically induced aggregation of insulin using dithiothreitol (DTT) in the presence of gold nanoparticles was studied in the same manner as was done for ADH. Similar prevention property of gold nanoparticles was established by making the observation independent of the method of denaturation or the type of protein used in the prevention experiments. In Chapter 5 huge second harmonic light scattering (SHS) signal from pure gold nanoparticles has been used to measure the free energy of interaction of ADH and insulin with nanoparticles in solution, for the first time. The change in the second harmonic scattered signal was monitored which decreased steadily as a function of added protein concentration to the aqueous solution of gold nanoparticles. The fitting of the second harmonic signal decay was done with a modified Langmuir adsorption isotherm to extract the free energy change in the interaction and the number of protein molecules adsorbed on the surface. In Chapter 6 I have demonstrated a way to recover the adsorbed ADH and insulin from the gold nanoparticle surface and tested the activity of ADH by an assay. The structure of the proteins in the adsorbed state has been probed by CD spectroscopy and described in this chapter. It is found that ADH retains its activity in the adsorbed state. Both the proteins retain the native secondary structures in their adsorbed state. However, the structures change drastically under denaturing conditions. In Chapter 7 the effect silica nanoparticles which are known to have hydrophilic surface has been examined on the aggregation of ADH and insulin in pretty much the same way as was done with gold nanoparticles. The efficiency of silica nanoparticle was found to be lower compared to gold nanoparticles. In addition, the size dependency of prevention efficiency of silica and gold nanoparticles was found to be completely opposite to each other. In Chapter 8 I have presented the overall summary and possible future directions of this work

Kyoto University (京都大学) / 0048 / 新制・論文博士 / 博士(工学) / 乙第12460号 / 論工博第4042号 / 新制||工||1497(附属図書館) / 28070 / (主査)教授 岩田 博夫, 教授 伊藤 紳三郎, 教授 辻井 敬亘 / 学位規則第4条第2項該当

L'objectif de cette thèse est de créer de nouvelles surfaces nanostructurées avec des revêtements bioactifs et d'étudier leurs propriétés physico-chimiques afin de développer de meilleurs modèles d'implants dentaires et d'optimiser leur ostéo-intégration. Cette fonctionnalisation a été réalisée en deux étapes ; on a commencé par la nano structuration de la surface de TiO2 par anodisation pour créer des sites réactifs sur les bords extérieurs des nanotubes qui agissent comme des points d'ancrage du revêtement bioactif et améliorent le verrouillage mécanique entre le revêtement et le substrat. Ensuite, la modification chimique est réalisée par revêtement de la surface nanostructurée avec des revêtements bioactifs de phosphate de calcium (CaP) et phosphate de calcium dopé par strontium (Sr.CaP). Ce revêtement a été réalisé par électrodéposition pulsée. La caractérisation physico-chimique par MEB, XPS et IR a montré que le dopage avec Sr favorise un composé non-apatitique similaire à DCPD ou DCPA (Dicalcium Phosphate Dihydrate ou Anhydrous), tandis que le revêtement de CaP non-dopé ressemble à un composé d'apatite amorphe ACP. L'addition de strontium s'offre le double avantage de favoriser les mécanismes de la croissance cellulaire et d'obtenir une phase inorganique avec de bio-performances meilleurs que les composés apatitiques. Nous avons également évalué les propriétés d'adsorption de ces surfaces fonctionnalisées en étudiant l'adsorption des protéines (BSA).Cette adsorption a été réalisée sur nanotubes fonctionnalisés vierges, nanotubes enrobés avec CAP et CAP dopé Sr et elle a été évalués selon le temps de déposition et la valeur du pH de la solution qui affecte la charge de la protéine et de la surface. L'évaluation cinétique et structurelle révèle diffèrent géométries d'adsorption en fonction du pH, du temps d'adsorption et aussi en fonction de la nature chimique de la surface. Ces résultats de l'adsorption et conformation de protéine forment une base de données pour comprendre et contrôler ses activités et réactions avec le vivant lorsqu'elle est utilisée dans le system des implants dentaires / The objective of this thesis is to create new nanostructured surfaces with bioactive coatings and to study theirs physicochemical properties in order to develop better dental implants designs and promote their osseointegration. This functionalization was performed in two steps; starting by the nanostructuration of TiO2 surface by anodisation to create reactive sites on the edges of titanium nanotubes which acts as points of “attachment" to bioactive coatings. The second step was the surface chemical modification by coating the nanostructured surface with bioactive coatings of calcium phosphate (CaP) and strontium doped calcium phosphate (Sr.CaP). This coating was performed by pulsed electrodeposition. The physicochemical characterization by XPS, SEM and IR showed that doping with Sr promotes a non-apatitic compound similar to DCPD or DCPA (Dicalcium Phosphate Dihydrate or Anhydrous), while undoped CaP coating looks like an amorphous apatite-like compound ACP. The addition of strontium has the double advantage of optimizing the cellular multiplication and of giving an inorganic phase with bio-performance better than apatitic compounds. We also evaluated the adsorption proprieties of these functionalized surfaces by investigating the adsorption of proteins (BSA). This adsorption was performed onto tblank nanotubes, nanotubes coated with CaP and Sr doped CaP and evaluated according to deposition time and to the pH value of the solution that affect both protein and surface charge. The kinetic and structural evaluation reveals different adsorption geometries according to pH and adsorption time and also according to the chemical nature of surface. Such results of protein adsorption and conformation may form a database to understand and control protein activities and reactions with living body when used for dental implants system

Im Rahmen dieser Arbeit wurden für die Herstellung neuartiger funktioneller Oberflächenbeschichtungen Polymerbürstensysteme basierend auf linearen, thermoresponsiven Poly-2-oxazolinen (POX) entwickelt und ausführlich charakterisiert. Als Grundbaustein für die Herstellung von POX-Bürsten wurden drei endfunktionalisierte thermoresponsive POX mittels kationisch ringöffnender Polymerisation synthetisiert, wobei jeweils 2-Cyclopropyl-2-oxazolin (cPrOX) als thermoresponsive Wiederholungseinheit und 2-Methyl-2-oxazolin (MeOX) als hydrophiles Comonomer zu verschiedenen Anteilen verwendet wurden. Mittels VIS-spektroskopischen Trübungsmessungen wurde für alle POX in Wasser ein LCST-Entmischungsverhalten mit einem reversiblen und scharfen Phasenübergang nachgewiesen, wobei die Trübungstemperaturen stark von der Polymerhydrophilie sowie der Molmasse und der Polymerkonzentration in Lösung abhingen. Die Herstellung der POX-Polymerbürsten auf der Basis der synthetisierten POX erfolgte über einen „grafting to“-Ansatz, bei welchem die Polymere in einem thermisch initiierten Prozess über ein funktionalisiertes Kettenende kovalent an ein Substrat angebunden wurden. Als Hauptmethode zur Charakterisierung der physikochemischen Eigenschaften der hergestellten Schichten, insbesondere deren temperaturabhängiges Schaltverhalten in Wasser, wurde spektroskopische Ellipsometrie verwendet. Zusätzlich kamen Rasterkraftmikroskopie, Kontaktwinkel und Quarzkristallmikrowaage mit Dissipationsaufzeichnung zum Einsatz. Im Gegensatz zum sehr scharfen, diskontinuierlichen Phasenübergang der POX in Lösung konnte für alle POX-Bürsten ein kontinuierlicher Übergang von einem gestreckten Bürstenzustand bei niedrigen Temperaturen in einen kollabierten Zustand bei hohen Temperaturen bestimmt werden, wobei das Quellvermögen und die temperaturabhängigen Quellkurvenverläufe durch die Polymereigenschaften und die Bürstenparameter beeinflussbar waren. Durch die Kombination eines POX mit Polyacrylsäure (PAA) als zweite Komponente konnten zudem neuartige binäre Polymerbürstensysteme hergestellt werden, welche ein komplexes pH- und temperaturabhängiges Schaltverhalten sowie ein steuerbares Proteinadsorptionsvermögen in Abhängigkeit von der Bürstenpräparationsmethodik, der POX-PAA-Zusammensetzung sowie der Temperatur und dem pH-Wert der umgebenden Pufferlösung aufwiesen. Zur ausführlichen Charakterisierung der Schichteigenschaften wurde neben den bereits benannten Methoden der spektroskopischen Ellipsometrie, Rasterkraftmikroskopie und der Kontaktwinkelmessung auch Röntgenphotoelektronenspektroskopie genutzt. Abschließende Zelladhäsionsexperimente mit humanen mesenchymalen Stammzellen auf den bürstenmodifizierte Oberflächen unter physiologischen Bedingungen offenbarten deutliche Unterschiede in der Affinität der Zellen zur Adhäsion auf POX-Homopolymerbürsten in Abhängigkeit der Bürstenhydrophilie. Darüber hinaus konnte die Zelladhäsion auch auf POX-PAA-Mischbürstensystemen gesteuert werden.

Nanomedicine is based primarily on the concept of drug formulation through nanotechnology. The main idea is based on the encapsulation of an active ingredient by a nanoparticle (NP) to allow it to accumulate in tumors, to penetrate a biological barrier or to target a biological component. However, the performance of these formulations is disappointing, and, in recent years, it has been noticed that their effectiveness has not improved in the last decade. Some recent hypotheses highlight our lack of knowledge about the interactions of nanotechnologies with living organism and more particularly the lack of techniques to quantify these interactions. We therefore explore in this thesis the development and adaptation of a new microscopy technique, dynamic differential microscopy (DDM), to study the interactions of nanotechnologies with biological matrices. Two subjects are discussed, the first on the interactions of NPs with the proteins of biological fluids and, the second one, on the capacity of NPs to diffuse in interstitial tissues. First, we reviewed quantification techniques that were allowing the measurement of protein adsorption at the surface of NPs. We then identified fundamental questions of this adsorption, namely, if it was generally structured in monolayers or in multilayers and if it was reversible or irreversible. A meta-analysis, based on these questions, could therefore guide the development of the DDM technique to measure protein adsorption and therefore answer these questions. The methodology proposed for the quantification of protein adsorption is based on the measurement of the fluorescence signal which comes from fluorescently tagged proteins adsorbed on non-fluorescent NPs. This methodology was successfully applied for the quantification of the adsorption of lysozyme, albumin and serum proteins. The technique demonstrated that all the proteins studied adsorbed in monolayers and that their adsorption was reversible. An atypical adsorption mechanism which was also hypothesized in our meta-analysis was evidenced by DDM as well. Next, we applied DDM to study the diffusion of NPs in extracellular matrices. The contribution of deformability has been a parameter studied in terms of its relation to improve their diffusion within these confined environments. The diffusion of "soft" NPs was compared to that of "hard" NPs in an agarose gel, mimicking the extracellular matrix. Soft NPs have been observed to diffuse up to 100 times faster than hard NPs of the same size. Evaluation of the hydrodynamic and electrostatic contributions determined that the soft NPs shrinks in the gel, boosting their diffusion in comparison to hard NPs. In summary, this work highlights the important contribution of analytical techniques to the field of nanotechnologies applied to pharmacy and to our understanding of their interactions with living organisms. It is clear that the contribution of these techniques to our detailed understanding of nanomedicine properties has a direct relation with their clinical translation potential. / La nanomédecine repose essentiellement sur le développement de nouvelles formulations pour délivrer les médicaments à partir de nanotechnologies. L’idée principale est que l’encapsulation d’un principe actif par une nanoparticule (NP) pourrait lui permettre de s’accumuler dans des tumeurs, de pénétrer une barrière biologique ou bien pour cibler une composante biologique. Or, les performances de ces « nano-formulations » sont décevantes et, depuis quelques années, il a été remarqué que leur efficacité ne semble pas avoir évoluée dans le temps. De récentes hypothèses mettent de l’avant notre manque de connaissances vis-à-vis les interactions des nanotechnologies avec les éléments du vivant, et plus particulièrement, le manque de techniques robustes permettant de quantifier ces interactions. Nous proposons donc dans cette thèse le développement et l’adaptation d’une nouvelle technique de microscopie, la microscopie différentielle dynamique (DDM), pour étudier les interactions entre les nanotechnologies et les matrices biologiques. Deux thématiques seront abordées, la première, les interactions des NPs avec les protéines des fluides biologiques et, la seconde, la capacité des NPs à diffuser dans des tissus interstitiels. D’abord, nous avons revus les techniques de quantification permettant la mesure de l’adsorption de protéines à la surface des NPs. Nous avons ensuite identifié les questions fondamentales en lien avec cette adsorption. Deux phénomènes sont largement débattus dans la littérature, il s’agit de la formation de multicouches et de la réversibilité de l’adsorption. Une méta-analyse a donc permis d’orienter le développement de la technique par DDM pour mesurer l’adsorption de protéines, dans le but de répondre à ces interrogations. La méthodologie proposée pour la quantification de l’adsorption de protéines à la surface des NPs repose sur la mesure du signal de fluorescence de protéines fluorescentes adsorbées à la surface des NPs non fluorescentes. Cette méthodologie a été appliqué avec succès pour la quantification de l’adsorption des protéines du sérum, du lysozyme et de l’albumine. La technique a d’ailleurs permis de montrer que toutes les protéines étudiées s’adsorbaient en monocouches et que leur adsorption était réversible. Un mécanisme d’adsorption atypique a été mis en évidence dans le cadre de nos expériences et un parallèle a pu être fait avec certaines hypothèses émises avec notre méta-analyse. Ensuite, nous avons appliqué la DDM pour l’étude de la diffusion des NPs dans des matrices extracellulaires. La déformabilité des NPs a été étudiée afin de définir plus précisément sa contribution dans la diffusion à l’intérieur de milieux confinés. La diffusion des NPs « molles » a été comparée à celle des NPs « dures » dans un gel d’agarose, mimant la matrice extracellulaire. Les NPs molles ont été en mesure de diffuser jusqu’à 100 fois plus rapidement que les NPs dures de même taille. L’évaluation des contributions hydrodynamiques et électrostatiques a permis de déterminer que la taille des NPs molles, réduisant dans le gel, leur accordant un avantage diffusif par rapport aux NPs dures. En sommes, ces travaux ont permis de mettre en évidence l’importance des techniques analytiques pour l’étude des nanotechnologies appliquées à la médecine et pour affiner notre compréhension de leurs interactions avec le vivant. Il est clair que la contribution de ces techniques à l’avancement de nos connaissances théoriques relatives aux nanotechnologies aura un impact direct sur leurs chances d’effectuer une transition vers la clinique.