Amphiphilic tri- and penta-block copolymers containing a polyurethane central block with pendant carboxylic acid groups flanked by hydroxyl functional polyether tails were synthesized. Our intention was to investigate the activities of these copolymers as dispersants for magnetite nanoparticles in biological media. A benzyl alkoxide initiator was utilized to prepare poly(ethylene oxide) (BzO-PEO-OH), poly(propylene oxide) (BzO-PPO-OH) and poly(ethylene oxide-b-propylene oxide) (poly(BzO-EO-b-PO-OH)) oligomeric tail blocks with varying lengths of PEO and PPO. The oligomers had a hydroxyl group at the terminal chain end and a benzyl-protected hydroxyl group at the initiated end. The polyether oligomers were incorporated into a block copolymer with a short polyurethane segment having approximately three carboxylic acid groups per chain. The block co-polyurethane was then hydrogenated to remove the benzyl group and yield primary hydroxyl functionality at the chain ends. End group analysis by 1H NMR showed the targeted ratio of PEO to PPO demonstrating control over block copolymer composition. Number average molecular weights determined by both 1H NMR and GPC were in agreement and close to targeted values demonstrating control over molecular weight. Titrations of the pentablock copolymers showed that the targeted value of approximately three carboxylic acid groups per chain was achieved. Heterobifunctional poly(ethylene oxide) (PEO) and poly(ethylene oxide-b-propylene oxide) (PEO-b-PPO) copolymers were synthesized utilizing heterobifunctional initiators to yield polymers having a hydroxyl group at one chain end and additional moieties at the other chain end. For PEO homopolymers, these moieties include maleimide, vinylsilane, and carboxylic acid functional groups. Heterobifunctional PEO oligomers with a maliemide end group were synthesized utilizing a double metal cyanide coordination catalyst to avoid side reactions that occur with a basic catalyst. PEO oligomers with vinylsilane end groups were synthesized via alkoxide-initiated living ring-opening polymerization, and this produced polymers with narrow molecular weight distributions. Heterobifunctional PEO-b-PPO block copolymers were synthesized in two steps where the double metal cyanide catalyst was used to polymerize propylene oxide (PO) initiated by 3-hydroxypropyltrivinylsilane. The PPO was then utilized as a macroinitiator to polymerize ethylene oxide (EO) with base catalysis. Heterobifunctional PEO and PEO-b-PPO block copolymers possessing carboxylic acid functional groups on one end were synthesized by reacting the vinyl groups with mercaptoacetic acid via an ene-thiol addition. / Ph. D.

Amphiphilic block copolymers consisting of poly(ethylene oxide) and poly(lactide) have great potential for formulating drug delivery systems. Our approach was to synthesize poly(ethylene oxide-b-D,L-lactide), (PEO-b-PDLLA), block copolymers with controlled molecular weights and good functionality on the poly(ethylene oxide) end for the design of potential core-shell delivery vehicles for HIV drugs. PEO-b-PDLLA block copolymer was used as a polymeric nanocarrier to encapsulate the HIV protease inhibitor, Ritonavir, within magnetite nanoparticles. Well-defined multifunctional polymeric nanoparticles with controlled sizes and size distributions were fabricated by rapid nanoprecipitation using blends of the PEO-b-PDLLA block copolymer with poly(L-lactide), (PLLA) homopolymer. Heterobifunctional PEO oligomers were directly prepared by initiating ethylene oxide with functional alcohols bearing vinylsilane, vinylether and maleimide moieties to provide appropriate end groups for conjugating targeting ligands. The polyethers with narrow molecular weight distributions were utilized as macroinitiators for the synthesis of poly(lactide) block. Heterobifunctional diblock copolymers possessing carboxylic acids were prepared from ene-thiol addition reaction of mercaptoacetic acid across the vinyl group on the PEO end, while preserving the hydroxyl functionality on the other end. Additionally, PDLLAs bearing maleimide functionality with controlled molecular weights were synthesized using maleimide functional initiator. End group modification was performed via  Michael addition using cysteamine hydrochloride to introduce an amino group over the vinyl bond. The resulting carboxylic acid functional PEO-b-PDLLA diblock copolymers, and amino functional PDLLAs are potential biocompatible polymers that can be utilized to encapsulate an array of bioactive molecules, targeting ligands. / Master of Science

Chapter 1 includes a review on dendrimers, their synthesis and applications, with a particular focus on urea-linked dendritic species. The synthetic strategy utilised in this body of work was based on the preparation of a number of branched synthetic building blocks possessing differing terminal functionality. These branched dendrons, bearing three terminal residues and based on the cheap starting material tris(hydroxymethyl)aminomethane (TRIS) 23, involved the coupling of 3.3 equivalents of an appropriately para-substituted benzoic acid chloride with BOC protected TRIS 24 in DCM in the presence of triethylamine. The p-nitro, p-methoxy and p-methyl benzoyl chloride starting materials were obtained commercially, whilst N-(4-carboxyphenyl)maleimide was synthesised according to literature procedures. The BOC protected dendrons (25–27, 34) were synthesized in yields ranging from 50–92%. Deprotection of the BOC protected dendrons 25 and 26 in DCM with TFA, followed by the addition of 1M Na2CO3 afforded the TFA salts 35 and 36, respectively. The corresponding free base amines 37 and 38 were obtained on further treatment of the TFA salts with sodium carbonate. Deprotection of the BOC protected dendrons 27 and 34 afforded the free amines 39 and 48 directly after treatment with sodium carbonate. Synthesis of functionalised branched molecules containing 6- and 9-peripheral functionalities was achieved by refluxing 2 or 3 equivalents of the free amine dendrons with the bi- or tri- functional isocyanate cores, 15 and 45, in refluxing DCM, in most cases the products precipitated from the reaction mixture after 18 h and were isolated simply by filtration, otherwise the removal of the solvent from the reaction mixture afforded the spectroscopically pure product. Conversion of the peripheral nitro functionalised species 14 and 21 to the corresponding amines occurred smoothly via hydrogenation using 5% Pd/C under elevated temperature and pressure (DMF, 55 ºC, 600 psi) and afforded the polyamine 6-mer 51 in 92% yield and the 9-mer 50 in 90% yield, respectively. Similarly, conversion of the methoxy coated 9-mer 42, to the corresponding phenolic compound (AlBr3, dodecane thiol, DCM) afforded the 9-mer polyphenol 52 in an 87% yield. All compounds prepared were fully characterised and crystal structures were obtained for 26 and 35. Chapter 2 includes a review on self-assembled monolayers of organosulfur compounds on gold, applications, patterning techniques and techniques for the characterisation of these surfaces. A number of surface monomers were successfully synthesized, to be used for various surface functionalisations, including the formation of an amine reactive N-hydroxysuccinimide (NHS) disulfide 53, via the DCC coupling of 11,11’-dithiobisundecanoic acid 54 with N-hydroxysuccinimide with an isolated yield of 30%. A novel protein-resistant monomer 58 was also synthesized from 11-undecanoic acid 55 via an acid chloride coupling with triethylene glycol monomethyl ether 58, and isolated in a 72% yield. A number of attempts were made to produce an acyl azide SAM monomer 59, with success finally achieved via the acid chloride coupling of 11,11’-dithiobisundecanoic acid 54 with 5-amino-1,3-benzenedicarbonyl diazide 62 to produce 59 with an isolated yield of ~ 30%. Gold surfaces were prepared on atomically flat silicon wafers using an argon-ion sputterer. SAM films were formed on the gold surfaces via traditional solution based self-assembly methodology. A UV patterning protocol was developed, and a successful patterning trial using the NHS terminated monomer to backfill the UV exposed areas of a dodecane thiol monolayer was achieved and visualized using AFM and fluorescence microscopy after treating the surface with aminofluorescein. The covalent attachment of green fluorescent protein to the monolayer surface via reaction with the NHS terminated monolayer was demonstrated. The fluorescence of the biomolecule was preserved. The formation of a monolayer using the acyl azide monomer 59, was characterised by contact angle and XPS analysis. However, preliminary studies into the activation of the acyl azide surface into the reactive isocyanate were unsuccessful. There is however, significant scope for further investigations into this interesting surface technology. Chapter 3 includes a review on heterobifunctional linker technology with a particular focus on amine and thiol reactive moieties and literature examples of heterobifunctional linkers of this type. Synthesis of heterobifunctional reagents such as 71 and 74 via a two step synthetic methodology involving the coupling of maleic anhydride with the parent amino-acids in acetic acid, followed by a one pot cyclisation and NHS esterification using DCC in DMF were successful, with overall yields of 9% and 32% respectively for the two reaction steps. The one pot extension of 74 with 6-aminohexanoic acid, followed by DCC, facilitated NHS esterification was achieved successfully in a yield of 30%. Attempts to extend 74 with the synthesised amino acid 88 were unsuccessful due to the insolubility of 88 in organic solvents. A different synthetic strategy was devised towards the synthesis of 85 with the coupling of 74 and mono BOC protected ethylene diamine 91 in DCM to give 93 in an isolated yield of 60%. Deprotection of the terminal amine was achieved via reaction with TFA in DCM however all attempts to prepare the free amine were unsuccessful. Subsequent attempts to couple 94 with both succinic anhydride and 92 were unsuccessful. A maleimide functionalized crown ether was synthesised as a molecule for protein modification via the reaction of 74 with 4’-aminobenzo-15-crown-5 97 to produce 98 in an 80% yield. All compounds were fully characterised with crystal structures obtained for 74, 79 and 89.

Doctor of Philosophy / Department of Chemistry / Christer B. Aakeröy / A set of multifunctional molecules [isomeric forms of 1-(pyridylmethyl)-2,2'-biimidazole] was synthesized and subjected to systematic co-crystallizations with selected hydrogen- and halogen-bond donors in order to explore the impact of interaction type, geometry and electrostatics on the resulting supramolecular architectures. The structural outcome with hydrogen-bond donors (carboxylic acids) is somewhat unpredictable because of the presence of the acid···biimidazole heterosynthon that can compete with biimidazole···biimidazole homosynthon. In contrast, the solid-state supramolecular behavior of those probe molecules is largely unchanged in halogen-bonded co-crystals. Only two types of primary interactions, the two-point hydrogen bonds responsible for pairing biimidazole moieties, and the single-point halogen bonds responsible for the co-crystal formation and structure extension, are present in these systems. The results highlight that, by incorporating geometric biases along with orthogonal interactions, one can effectively prevent synthon crossover which is of paramount importance in complex crystal engineering endeavors. Heterobifunctional ligands pave the way for elaborate metallo-supramolecular systems, and are also useful for combining metal-ligand bonding with other types of non-covalent interactions. Nine new acetylacetonate ligands featuring either pyridyl- or thiophenyl-heterocycles were successfully prepared, and their metal binding abilities were studied with selected di- and tri-valent transition metal ions. As expected, the acetylacetonate ligation to metal dications remains consistent. In each case, the metal is four-coordinate and resides in a square planar environment. Differences in the overall architectures arise from the role played by the terminal heterocycles and the solvent. In seven (out of nine) structures, the heterocyclic end is involved in a structure-directing interaction and it is more prevalent in ligands bearing 4-pyridinyl unit. Divergent molecules containing bulky substituents tend to produce porous materials via frustrated packing. Two rigid tetrahedral cores, tetraphenylmethane and 1,3,5,7-tetraphenyladamantane, grafted peripherally with four (trimethylsilyl)ethynyl moieties were found to have only isolated voids in their crystal structures. Hence, they were modified into tecton-like entities, tetrakis(4-(iodoethynyl)phenyl)methane [I₄TEPM] and 1,3,5,7-tetrakis(4-(iodoethynyl)phenyl)adamantane [I₄TEPA], and the effect of motif-forming characteristics of iodoethynyl units on molecular arrangement and crystal porosity was analyzed. I₄TEPM not only holds increased free volume compared to its precursor, but also forms one-dimensional channels. Furthermore, it readily co-crystallizes with Lewis basic solvents to afford two-component porous materials even though they suffer from stability issues. As the binding sites in I₄TEPM and I₄TEPA are tetrahedrally-predisposed, they can be further utilized for the modular assembly of highly symmetric, three-dimensional extended architectures. With that in mind, these two building blocks were subsequently allowed to react with various halide salts, and it was found that the reactions between I₄TEPM and tetraphenylphosphonium halides readily yield four-fold interpenetrated diamondoid networks sustained by C–I⋯X⁻ (X⁻ = chloride, bromide, iodide) halogen-bonding interactions. The halide anions exhibit mutual-induced fitting of their coordination and act as four-connecting tetrahedral nodes, while the tetraphenylphosphonium cations render essential templating information and structural support.

Well-defined heterobifunctional homopolyethers and amphiphilic block copolyethers containing a variety of functionalities were designed, synthesized, and characterized via GPC and 1H NMR. These have included controlled molecular weight cholesterol-PEO-OH, mono- and trivinylsilyl-PEO-OH, monovinylsilyl-PEO-PPO-OH, monovinylsilyl-PEO-PPO-PEO-OH, maleimide-PEO-OH, stearyl alcohol-PEO-OH, propargyl alcohol-PEO-OH, trivinylsilyl-PPO-OH, trivinylsilyl-PPO-PEO-OH, and benzyl alcohol-initiated poly(allyl glycidyl ether)-OH. The focus of polymers utilized in this study involved the mono- and trivinylsilyl polyethers. The vinylsilyl endgroups on these materials were functionalized with various bifunctional thiols through free radical addition of SH groups across the vinylsilyl double bonds. The resultant end-functional polyethers were adsorbed onto magnetite nanoparticles and the stabilities of the polymer-magnetite complexes were compared as a function of the type of anchoring moiety and the number of anchoring moieties per chain. Anchoring chemistries investigated in this work included carboxylates, alkylammonium ions, and zwitterionic phosphonates. The anchor group-magnetite bond stability was investigated in water and phosphate buffered saline (PBS). Through these studies, the zwitterionic phosphonate group was shown to be a better anchoring group for magnetite than either carboxylate or ammonium ions. Tri-zwitterionic phosphonate anchor groups provided stability of the complexes in PBS for a broad range of polymer loadings. Thus, investigations into the stability of polyether-magnetite complexes in PBS focused on hydrophilic zwitterionic phosphonate-PEO-OH and amphiphilic zwitterionic phosphonate-PPO-b-PEO-OH oligomer coatings on the surface of magnetite. Superparamagnetic magnetite nanoparticles are of interest as potential contrast-enhancement agents for MRI imaging. Thus, transverse NMR relaxivities of these complexes were studied as a function of chemical composition and nanostructure size and compared to commercial contrast agents. The amphiphilic polyether-magnetite nanoparticles were shown to be stable in both aqueous media as well as physiological media and have much higher transverse relaxation values, r2, than those of commercial contrast agents and other materials in the literature. / Ph. D.

This thesis covers different topics in the field of synthetic organic chemistry combined with the field of surface science and glycobiology. First, the text presents a series of orthogonally protected oligosaccharides (tri-, penta-, and heptasaccharides) of varying length and structures, which are synthesized with the aim of developing novel heterobifunctional biocompatible cross-linkers. Successful conjugation with different chemical handles is also described and used to illustrate the potential implementation of defined carbohydrate based compounds have potential use in biosensing applications. The results of incubation experiments using living cells indicate that the linker is incorporated into cell surfaces and enriched in microdomains. Second, synthesis of various saccharide-terminated alkane thiols immobilized on gold surfaces is reported. The protein adsorption and antifouling characteristics of these surfaces were investigated using model proteins and the common fouling organisms, Ulva linza and Balanus amphitrite. Further, oligo(lactose)-based thiols (di-, tetra-, and hexasaccharides) were synthesized and immobilized on gold nanoparticles to investigate how well these rigid, rod-like oligosaccharides can stabilize such nanoparticles for future use in constructing hybrid nanoparticles. Finally, the thesis describes synthesis of a systematic series of oligo(ethylene) glycols possessing either hydrogen- or methyl-terminated groups. Investigation of the fundamental characteristics of self-assembled monolayers, will give important insights into the design of protein repellant surfaces.

Copolymers that contain terminal or pendent functional groups have great potential in the biomedical area due to their biocompatibility and tunable properties.1-3 In this research, two vinyl functional epoxides, vinyldimethylsilylpropyl glycidyl ether (VSiGE) and ethoxy vinyl glycidyl ether (EVGE), were synthesized. These heterobifunctional monomers were polymerizable via the epoxide groups and can be functionalized via thiol-ene reactions through the pendent vinyl groups. A series of amphiphilic block copolyethers based on poly(ethylene oxide) and poly(1,2-butylene oxide) that incorporate VSiGE or EVGE were synthesized and characterized. The vinyl ether and vinyl silane functional groups were functionalized after polymerization and the functional polymers formed pH-sensitive micelles in aqueous medium. The copolyethers were loaded with ritonavir yielding well-controlled nanoparticles. Poly(L-glutamic acid) is comprised of naturally occurring L-glutamic acid repeating units that are linked together with amide bonds. In this research, we have prepared magnetic block ionomer complexes based on poly(ethylene oxide)-b-poly(L-glutamic acid) copolymers. This is of interest due to the biocompatibility and biodegradable nature of the poly(L-glutamic acid) component of the backbone. Allyl- and thiol-functional poly(ethylene oxide)-b-poly(L-glutamic acid) copolymers were also synthesized and coated onto the surface of iron oxide nanoparticles. Allyl- and thiol-tipped single particles were reacted with each other to prepare magnetic clusters. Transverse relaxivities of the clusters were found to be significantly higher than that of single particles. One major problem in commercial development of therapeutic proteins is their poor transport across cellular membranes and biological barriers such as the blood-brain barrier (BBB). One solution to this problem is to modify proteins with amphiphilic block copolymers such as PEO-b-PPO-b-PEO, Pluronics®. However, it isn't possible to independently tune the two PEO block lengths with commercial Pluronics® since a difunctional PPO macroinitator is utilized to grow both PEO blocks simultaneously (HO-EOn-b-POm-b-EOn-OH). Another challenge is introducing functional group which allows post-polymerization functionalization for specific applications. In this study, a series of heterobifunctional asymmetric amino-EOn1-b-POm-b-EOn2-OH block copolymers (APs) with different molecular weights of each block were synthesized and the amino terminal group was conjugated to an antioxidant enzyme, Cu/Zn superoxide dismutase (SOD1). The conjugates were characterized and their cellular uptake was investigated. / Ph. D.

Ce travail de recherche est consacré à l’ingénierie d’un nouveau nanobiohybride à base de nanorubans de titanates pour la médecine régénérative. Dans un premier temps, les nanorubans ont été synthétisés par traitement hydrothermal et leurs caractéristiques morphologiques, structurales et chimiques ont été définies. Une caractérisation fine par différentes techniques de microscopie électronique à transmission a notamment permis de déterminer leur épaisseur; dimension qui n’avait encore jamais été mesurée. Par la suite, les nanorubans de titanates ont été fonctionnalisés par différents PEG hétérobifonctionnels préalablement synthétisés au laboratoire. Ces polymères présentent à l’une de leurs extrémités des groupements fonctionnels spécifiques pouvant se coupler à de nombreuses molécules biologiques. Des peptides de type collagène contenant des sites de reconnaissance cellulaire ont alors été greffés sur ces extrémités. Le nanobiohybride ainsi formé devra permettre l'adhésion et la prolifération des cellules favorisant in fine la cicatrisation et la régénération tissulaire. Pour évaluer les propriétés biologiques du nouveau nanobiohybride, la cytoxicité et le pouvoir agrégeant des nanorubans de titanes ont été déterminés par des tests MTT, réalisés sur deux populations de cellules (cardiomyocytes et fibroblastes) et par des tests d’agrégation plaquettaire (sang humain). Enfin, dans le cas d’une utilisation pour favoriser le processus de cicatrisation, le nouveau nanobiohybride a été formulé sous forme d’un hydrogel d’alginate de sodium permettant une application directe sur les tissus lésés. Pour confirmer l’intérêt de cette formulation galénique, des premiers tests in vivo ont été réalisés / This research work is devoted to new nanohybrid engineering composed of titanate nanoribbons for regenerative medicine. Over a first phase, nanoribbons were synthesized by hydrothermal treatment and their morphological, structural and chemical features were defined. A fine characterization by means of different techniques of transmission electron microscopy mainly enabled to determine their thickness; dimension which had never been measured so far. Subsequently, titanate nanoribbons were functionalized by different home-made heterobifunctional PEG. Those polymers present at one of their extremities specific functional groups being able to couple with numerous biological molecules. Some collagen type peptides containing cellular recognition sites were grafted onto those extremities. The so-formed nanobiohybrid will permit cellular adhesion and proliferation favouring in fine tissue healing and regeneration. To evaluate new nanohybrid biological properties, titanate nanoribbons cytoxicity and aggregating power were determined by MTT tests, performed on two cell populations (fibroblasts and cardiomyocytes) and platelet aggregation tests (human blood). Finally, when used to promote healing process, the new nanobiohybrid was formulated in the form of sodium alginate hydrogel permitting a direct application on damaged tissues. To confirm the interest of this galenic form, initial in vivo tests were realized

L'objectif principal de la thèse porte sur la synthèse contrôlée et la caractérisation d’architectures macromoléculaires complexes originales à base de POE. Les POEs α-undécènyle-ω-hydroxy sont obtenus par polymérisation anionique par ouverture de cycle de l’oxyde d’éthylène. Le groupement hydroxyle est modifié pour accéder à des POEs α-undécènyle-ω-méthacrylate et des POEs α-undécènyle-ω-acétylène. Ces premiers POEs sont ensuite utilisés pour préparer soit des POEs à structure en peigne par ATRP dans l'eau soit par l'intermédiaire de réaction « click », des POEs à structure en étoile tétrafonctionnelles, tandis qu’avec les seconds permettent d’obtenir des PI-b-POE par réaction « click » avec le polyisoprène ω-azoture. Les extrémités de chaîne de POE commerciaux α-méthoxy-ω-hydroxy sont modifiées en POEs α-méthoxy-ω-allyle ou en POEs α-méthoxy-ω-undécènyle pour synthétiser par réaction d’hydrosilylation des étoiles de POE à structures en étoile octafonctionnelles. / The main objective of the thesis focuses on the controlled synthesis and the characterization of original and complex macromolecular architectures based on PEO. α-Undecenyl-ω-hydroxy PEOs are obtained by anionic ring opening polymerization of ethylene oxide. The hydroxyl group is modified to access to α-undecenyl-ω-methacrylate PEOs and α-undecenyl-ω-acetylene PEOs. These first PEOs are used to prepare either comb-shaped PEOs by ATRP in water or through by click reaction of tetrafunctional star-shaped PEOs. Whereas the second PEOs allow obtaining block copolymers PI-b-PEO via click reaction with ω-azide polyisoprene. The chain-ends of commercial α-methoxy-ω-hydroxy PEO are modified in α-methoxy-ω-allyl PEOs or in α-methoxy-ω-undecenyl PEOs to synthesize by hydrosilylation reaction octafunctional star-shaped PEOs.