The biomedical application of nanotechnology has come into the spotlight, with the promise of ‘personalised’ therapeutics that couple early diagnosis with targeted therapeutic activity. Due to the rapid growth of the biomedical applications of nanoparticles, along with the lack of understanding concerning their interactions with biomolecules, there is a pressing need for the development of standard methods directed at investigating the effect of introducing these unique particles into the human body. The central aim of this research is to establish a platform directed at assessing the biological fate of pioneering therapeutic particulate agents, such as metallophthalocyanines (MPcs) and multi-walled carbon nanotubes (FMWCNTs). In particular, we proposed, that Quartz Crystal Microbalance with Dissipation (QCM-D) technology may be employed to assess the composition of blood protein corona deposited on the therapeutic surface, and subsequently assess the biocompatibility of such particles. The proposed method of protein detection utilises the nanogram sensitivity of QCM-D technology to monitor highly specific antibody-antigen interactions. In particular those interactions which occur when probe antibodies are used to detect adsorbed blood proteins deposited on target particle-modified sensor surfaces. Protein detection analysis was directed toward identification of surface bound human serum albumin, complement factor C3c, and human plasma fibrinogen. Preliminary analysis of generic biomedical surfaces indicated human serum albumin demonstrates a higher binding affinity towards positively charged surfaces (i.e. cysteamine self-assembled monolayer), followed by hydrophobic surfaces. Detection of complement C3c, corresponded with literature, where lower levels were detected on negatively charged surfaces (i.e. mercapto undecanoic acid self-assembled monolayer), and higher levels of more hydrophobic surfaces (i.e. 11-amino undecane thiol self-assembled monolayer). Human plasma fibrinogen was observed to favour hydrophilic over hydrophobic self-assembled monolayer surfaces, which was in accordance with literature. Application of the proposed protein detection method for biocompatibility analysis of target therapeutic molecules, namely metallophthalocyanines and acid functionalised multi-walled carbon nanotubes, demonstrated a dependence on modified-surface film characteristics, such as surface charge and topography with regards to human serum albumin and human plasma fibrinogen analysis representing new insights into their potential biomolecular interactions The highest levels of detected human serum albumin and complement C3c were detected on the GePcSmix-modified surfaces. AlPcSmix-modified surfaces analysis suggested the highest levels of human plasma fibrinogen. Two methods of acid functionalisation were employed, using both nitric and sulphuric acid, and pure nitric acid. A general increase in detected human serum albumin, corresponding with an increase in functionalisation time, was observed. Complement C3c detection suggested an increase in deposited complement C3c, with increasing functionalisation time, when assessing nitric acid functionalised multi-walled carbon nanotubes, and a decrease, with increasing functionalisation time, when assessing nitric and sulphuric acid functionalised multi-walled carbon nanotubes. Analysis of human plasma fibrinogen was inconclusive, as were cytotoxicity experiments utilising MCF-7 cells in the presence of metallophthalocyanine complexes, raising simultaneously important considerations for their application and study. In the first such detailed examination of its kind it was concluded that the proposed method of protein detection, using QCM-D, allows for the rudimentary but rapid means of analysis of select protein corona deposited on particulate biomedical surfaces.

In this study, the templating role of bimolecular triple hydrogen bonded honeycomb network consisting perylene-3,4,9,10-tetracarboxydi-imide and melamine is investigated, using scanning tunneling microscopy. Although the stability of the network upon modification is a major obstacle toward higher complexity, three different approaches in this work highlight formation of successful architectures in a sequential way. 1. Insertion of pore modifier star shaped molecules based on tri(phenylene ethynylene)benzene core in the pores to construct a new template. 2. Insertion of iodinated molecules in the pores to study the network as a nanoreactor. 3. Electrochemical deposition of metals in the pores. Self-assembly monolayer of four different molecules based on tri(phenylene ethynylene)benzene core on uniform gold surface revealed different structures. The degree of the order within the structures depends highly on the symmetry of the molecules, and hence asymmetric molecule formed disordered structure. Upon insertion into the pores of the network, one of molecules did not match the pores size, while others fitted and illustrated rotation depending on the strength of their interaction with the network components and the substrate. The rotation is significantly reduced by modifying the molecules. These new architectures are used as templets hosting C₆₀ molecules which resulted in isolated single C₆₀ molecules. Self-assembly of iodinated molecule under different conditions on uniform gold surface leads to formation of different structures including monomers and dimers. Upon thermal treatment on the uniform surface oligomers are formed, whereas for the molecules confined in the pores of the network, the covalent bond formation was limited to dimerisation. Electrochemical copper deposition into the pores of the network under acidic condition (pH = 1 - 2) is not possible because of the stability of the network. However, by increasing pH of the electrolyte (pH = 5 – 7), a bilayer of Cu and anion is formed in the pores of the network, confirmed by scanning tunneling microscopy and X-ray photoelectron spectroscopy.

Ces travaux de recherche s’inscrivent dans le cadre du développement de nouvelles surfaces biocompatibles capables de contrôler l’adhésion d’agents pathogènes responsables de maladies neurodégénératives telles que les maladies de Creutzfeld Jacob, Alzheimer, Parkinson et Lewis. Deux axes de recherche ont été privilégiés. Notre approche se focalise en amont des dosages sur l’amélioration des procédures de stockage des prélèvements biologiques réalisés dans des tubes de type Eppendorf. Ces tubes en polypropylène induisent une perte du matériel génétique de plus de 70% accentuant la faible concentration en agent pathogène pour la détection immunoenzymatique. Dans le but de réduire les phénomènes indésirables d’adhésion des agents pathogènes à la surface des supports de stockage, deux voies de traitement ont été envisagées dans ce travail de thèse. La première consiste à modifier la surface du tube Eppendorf en une étape par décharge plasma fluoré, la seconde à créer de nouvelles surfaces hydrophiles en deux étapes couplant la technique des plasmas froids au greffage de polymères, les agents pathogènes pouvant être hydrophiles ou hydrophobes. Avec cette dernière technique, une voie originale a été abordée de part l’utilisation de solutions de greffage complexes composées à la fois de polymères et de molécules tensioactives. Les surfaces ainsi obtenues présentent une nano-structuration. Toutes les étapes de modification de la surface interne des tubes de stockage ont été caractérisées. Ces surfaces sont alors décrites selon leur caractère hydrophile ou hydrophobe grâce à la détermination des énergies de surface polaire et apolaire, selon leur charge de surface obtenue par mesure du potentiel d’écoulement, selon leur composition chimique déterminée par spectroscopie à photoélectrons X (XPS) et enfin selon leur topographie et leur rugosité relevées par microscopie à force atomique (AFM). Les interactions entre les groupements fonctionnels ainsi obtenus à la surface des tubes de stockage après les divers traitements et les protéines antigéniques considérées ont été interprétées en se référant aux différents modèles de l’adhésion pour des gammes de pH proches des protocoles biologiques usuels. Afin de s’assurer que ces nouvelles surfaces permettent bien une diminution de l’adhésion des agents infectieux sur la paroi interne des tubes de polypropylène, des analyses immunoenzymatiques ont été réalisées au sein des centres hospitaliers participant au projet STREP NEUROSCREEN n° LSHB-CT 2006-03 7719 (CRPP de Liège et CHU de Lyon). Ces analyses ont permis de montrer que la modification des surfaces entraîne une diminution de l’absorption des agents pathogènes jusqu'à 100% permettant ainsi une meilleure détection. / The research work presented in this thesis considers the development of newµbiocompatible surfaces that are able to control the adhesion of specific proteins responsible for the development of neurodegenerative diseases such as Creutzfeldt–Jakob, Alzheimer, Parkinson and Lewis body disease. Our approach was focused on problems prior to the detection step, which were never considered before, particularly on the improvement of Eppendorf tubes that are used for the storage of body fluids like cerebrospinal fluid and blood. Namely these tubes made of polypropylene induce the depletion of biological material, in some cases even over 70%, resulting in a low concentration of these proteins for the further immunoenzymatic detection. With the purpose to reduce the adhesion of specific proteins on the surface of supports, two courses of treatments were anticipated. The first one consists of surface modification by highly reactive fluorine plasma treatment and the second one incorporates development of new hydrophilic surfaces by coupling two techniques, plasma activation and subsequent grafting of polymer materials. With the latter approach, an original way of surface modification has been attained by using complex solutions of polymers and surfactants that permits controlled configuration of nanostructured surfaces. All steps of surface modifications were well characterized by different physicochemical methods. The surface hydrophilic/hydrophobic character was determined by measurements of polar and apolar surface energy, surface charge by magnitude of zeta potential, surface chemistry was evaluated by x-ray photoelectron spectroscopy (XPS), while the surface roughness and topography were monitored by atomic force microscopy (AFM). The interactions between functional groups of treated supports and proteins were interpreted referring to different models of adhesion established for a range of pH values close to the classical biological protocols. Finally, in order to validate that the new surfaces are able to prevent or decrease the adhesion of neurodegenerative agents on the surfaces of Eppendorf tubes, the immunoenzymatic analyses were carried out in hospital centres of partners that were participating to the project STREP NEUROSREEN n° LSHB-CT-2006-03 7719 (Centre de Recherche sur les Protéines Prion; Liege (ULG), Hospices Civils de Lyon (CHUL) and Lancaster University (L-UNI)). These analyses showed that the treatments led to a decrease of antigen adsorption up to 100%, enabling (allowing) better detection of pathogenic agents.

Ce travail de thèse s’inscrit dans le contexte de la désulfuration par absorption des gaz utilisables dans des technologies émergentes comme les piles à combustible ou le procédé Fischer-Tropsch. Cette purification peut être réalisée à des températures modérées (200-300°C) sans régénération d'échantillon. L’absence de traitements à haute température permet d'envisager l'utilisation des solides nanostructurés qui devraient montrer naturellement une réactivité élevée. En fonction du schéma précis du procédé, on pourra être amené à éliminer des molécules de nature différente : H2S ou des molécules réfractaires comme mercaptans ou thiophènes. Pour répondre à ces exigences, la thèse s'est déroulée en deux parties. Dans la première partie des échantillons à base de nanoparticules de ZnO pur et dopé (M0,03Zn0,97O, M=Fe, Co, Ni, Cu) ont été préparés, caractérisés et leur réactivité vis-à-vis d’H2S a été étudiée. Il a été trouvé que le cuivre est le dopant qui permet d’améliorer le plus les performances de l’échantillon. L'étude du mécanisme de sulfuration par MET, DRX in situ et XPS a permis de conclure que la diffusion des ions O2- à travers la couche de ZnS est l'étape limitante de la sulfuration. Son accélération en présence de cuivre serait due à la formation d'une solution solide Cu2S-ZnS riche en lacunes anioniques. La deuxième partie du travail a été consacrée à l'élimination du thiophène. Un nouveau solide nanocomposite 2,8NiO-H1,8Ni0,6(OH)MoO4 a été mis au point. Sa structure ouverte sous forme de feuillets et sa capacité à se réduire facilement en présence d’H2 créent des conditions propices pour l'interaction avec le thiophène et permettent ainsi d'augmenter considérablement sa vitesse de sulfuration en comparaison avec l'échantillon classique à base de Ni/ZnO. Sa haute réactivité avec le thiophène en fait un excellent candidat pour éliminer les traces d’autres espèces sulfurées (COS, CS2, mercaptans). / This work focuses on the desulfurization by absorption of gases which can be used inemerging technologies such as fuel cells or Fischer-Tropsch process. This purification canbe achieved at low temperatures (200-300°C) without regeneration of the sorbent. Theabsence of high temperature treatment allow to use nanostructured solids wich can normallymust exibit higher reactivity. Depending on the process chosen, we will have to eliminatemolecules of different nature : H2S or molecules like mercaptans or thiophene. To answerthese requirements, the thesis work consisted of two parts. In the first part, nanoparticles ofpure and doped ZnO (M0,03Zn0,97O, M=Fe,Co,Ni,Cu) were synthesized and characterized,and their reactivity towards H2S was investigated. It was found that copper is the dopandwhich allow to improve considerably the performances of the sorbent. The study ofsulfidation mechanism by TEM, in situ XRD and XPS allow to conclude that diffusion ofO2- ions trough the ZnS layer is the rate limiting step of sulfidation. The acceleration in thepresence of copper may be due to formation of a solid solution Cu2S-ZnS rich in anionicvacancies. The aim of the second part of this work was to eliminate thiophene. A newnanocomposite solid 2,8NiO-H1,8Ni0,6(OH)MoO4 was prepared. Its layered open structureand its ability to be easily reduced create favorable conditions for interactions withthiophene, and in this way, allow to increase considerably its sulfidation rate (in comparisonwith the sulfidation rate of the classical sample Ni/ZnO). Its high reactivity with thiophenemakes it an excellent candidate for the elimination of other sulfure containing molecules(COS, CS2, mercaptans).

M.Sc. / With increasing industrial activities in South Africa, many of its waters are contaminated with both organic and inorganic pollutants. This is also a worldwide challenge which has resulted in an escalation in research efforts to combat it. Organic pollutants, for example, can be harmful to human health and the environment. Even when present at low concentrations, they tend to bio-accumulate and interact with endocrine systems. Therefore it is necessary that these pollutants are removed from effluents before they are integrated with water systems such as rivers and lakes. In an effort to utilize economic and efficient removal techniques, low cost and locally available materials have been used as potential adsorbents for the removal of these organic pollutants from synthetic wastewater. These coal-based materials were further fabricated into nanoporous sorbents through activation processes to improve their adsorption properties. The project reported in this dissertation was thus undertaken to explore, specifically, the efficacy of coal and coal-based sorbents (acid treated coal, activated carbon and activated fly ash) in their ability to remove phenolic compounds from wastewater.

MSc. (Applied Chemistry) / Remediation of POPs particularly the chlorinated compounds in water is therefore crucial. This research work describes the modification of polyethersulfone (PES) thin-film membrane composite (TFC) with functionalised carbon nanotubes (f-CNTs) using the phase invasion method. The oxidised CNTs were successfully decorated with Zero-Valent (ZV) Fe/Ni nanoparticles for the adsorption and degradation studies of polychlorinated organic pollutants (in this case the dichlorodiphenyltrichloroethanes (DDTs)). The in situ modification procedure was carried out using different quantities (0.04 wt%, 0.1 wt% and 0.2 wt%) of Fe/Ni-f-CNTs nanohybrids dispersed in a DMAc solution and dipping the polyethersulfone powder into a suspension containing the Fe/Ni-f-CNTs to form a nano-composite membrane. The formed composite membrane characteristics were investigated with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), contact angle (CA) and X-ray diffraction spectroscopy (XRD). The incorporation of nanohybrid in the PES membrane was found to increase the surface smoothness and the hydrophilicity of the composites. In addition, there was an increase in the adsorption of DDTs with increase in the nano-hybrid loading as indicated by the adsorption studies using the Langmuir isotherm and Freundlich isotherm studies. The data obtained from the batch studies closely fitted with the Langmuir isotherm based on the characteristic parameter RL found to lie within the standard range 0 < RL < 1 .

M.Sc. (Chemistry) / With the increase in the number of new Human Immunodeficiency Virus (HIV) infection and mortality rate worldwide partly due to diagnostic drawbacks which gives false negatives during the window period, it is imperative to find an alternative method of detection. The need for prompt, bed-side and field applicable analytical devices for biomedical purposes cannot be over emphasized in our fast paced world today. As a contribution to meeting these challenges, this dissertation reports (i) the development of novel electrochemical DNA/RNA aptamer biosensor for HIV sensing and (ii) the development of other DNA sequence specific electrochemical biosensors. These biosensors were based on composite platforms of dendrimer and gold nanoparticles...

No description available.

Microbial fuel cells (MFCs) are a promising form of alternative energy capable of harnessing the potential energy stores in organic waste. The oxygen reduction reaction (ORR) forms an integral role in the generation of electricity in MFCs however it is also a potential obstacle in enhancing the performance of MFCs. Platinum, a commonly used catalyst for the ORR, is expensive and rare. Significant research has been conducted into developing alternative catalysts. Metallophthalocyanines (MPc) have garnered attention for use as catalysts. Iron phthalocyanine (FePc) has been shown to have catalytic activity towards the reduction of oxygen. Coupling of the catalyst to nanostructured carbon materials, such as multi-walled carbon nanotubes, has been observed to have several advantages as nanostructures have a high surface-to-volume ratio. In this study, we have attempted to assess the suitability of FePc, both its bulk and nanostructured form, as an oxygen reduction catalyst and acid functionalized multi-walled carbon nanotubes for use as a catalyst support using electrochemical techniques such as cyclic voltammetry and electrochemical impedance spectroscopy. We showed, for the first time, the catalytic nature of nanostructured FePc towards the ORR. Applying the data obtained from the electrochemical analyses, electrodes were modified using FePc and MWCNTs and applied to an Enterobacter cloacae-based MFC. Several operational parameters of the MFC, such as temperature and ionic strength, were optimized during the course of the study. We showed that optimized FePc:MWCNT-modified electrodes compared favourably to platinum-based electrodes in terms of power densities obtained in a microbial fuel cell.

The research undertaken in these studies aimed to investigate the feasibility of developing and manufacturing innovative solid lipid carriers, such as solid lipid nanoparticles (SLN) and/or nanostructured lipid carriers (NLC) using a hot high pressure homogenization method, for didanosine(DDI). In addition, studies using in vitro differential protein adsorption were undertaken to establish whether the SLN and/or NLC have the potential to deliver DDI to the central nervous system (CNS). Prior to initiating pre-formulation, formulation development and optimization studies of DDI-Ioaded SLN and/or NLC, it was necessary to develop and validate an analytical method for the in vitro quantitation and analysis of DDI. An accurate, precise and sensitive RP-HPLC method with UV detection set at 248 nm was developed, optimized and validated for the quantitative in vitro analysis of DDI in formulations. Pre-formulation studies were designed to evaluate the thermal stability of DDI and to select and characterize lipid excipients that may be used for the manufacture of the nanocarriers. It was established that DDI is thermostable at temperatures not exceeding 163°C and therefore a hot high pressure homogenization technique could be used to manufacture DDI-loaded SLN and/or NLC. Lipid screening studies revealed that DDI is poorly soluble in both solid and liquid lipids. A combination of Precirol® ATO 5 and Transcutol® HP was found to have the best solubilizing-potential for DDI of all lipids investigated. The inclusion of Transcutol® HP into Precirol® ATO 5 changed the polymorphic form of the solid lipid from the stable 13-modification to a material that exhibited the co-existence between α- and β-polymorphic forms. The relatively high solubility of DDI in Transcutol® HP compared to Precirol® ATO 5 was an indication that a solid lipid matrix prepared from a binary mixture of Precirol® ATO 5 and Transcutol® HP was likely to have a higher loading capacity and encapsulation efficiency for DDI than a matrix consisting of Precirol® ATO 5 alone. Furthermore, the potential for the solid lipid matrix to exist in the α- and/or β-modifications when Transcutol® HP was added to Precirol® ATO 5 suggested that expulsion of DDI from a solid lipid matrix during prolonged storage periods was likely to be minimal. Therefore it was considered logical to investigate the feasibility of incorporating DDI into NLC and not in SLN. However, due to the limited solubility of DDI in lipids, formulation development of DDI-loaded NLC commenced using small quantities of DDI. Formulation development and optimization studies of DDI-loaded NLC were initially aimed at selecting a surfactant system that was capable of stabilizing NLC in an aqueous environment. Solutol® HS alone or a ternary mixture consisting of Solutol® HS, Tween® 80 and Lutrol® F68 was found to stabilize the nanoparticles in terms of particle size and the polydispersity index. The use of the ternary mixture as the surfactant system was preferred to using Solutol® HS alone as Lutrol® F68 and especially Tween® 80 have been successfully used to target the delivery of API to the brain. Aqueous DDI-free and DDI-Ioaded NLC containing increasing amounts of DDI were manufactured using hot high pressure homogenization at 800 bar for three cycles. The NLC formulations were characterized in terms of particle size, polydispersity index, zeta potential, and polymorphism, degree of crystallinity, encapsulation efficiency (EE), shape and surface morphology. The mean particle size for all formulations was below 250 nm with narrow polydispersity indices, indicating that narrow particle size distribution had been achieved. The d99% values for all formulations tested, were generated using laser diffractometry, and were below 400 nm, with span values ranging from 0.84 - 1.19 also suggesting that a narrow particle size distribution had been achieved. The zeta potential values measured in double distilled water with the conductivity adjusted to 50 μS/cm ranged from -18.4 to -11.4 mV. In addition, all the formulations showed a decrease in the degree of crystallinity as compared to the bulk lipid material and WAXS shows that the formulations existed in a single β-modification form. Furthermore DDI that had been incorporated into the NLC appeared to be molecularly dispersed in the lipid matrices. These parameters remained unaffected for most formulations following storage for two months at 25°C. In addition these formulations contained a mixture of spherical and non-spherical particles irrespective of the amount of DDI that was added during the manufacture of the formulations. These studies showed that it was feasible to develop and incorporate small amounts of DDI into NLC. However in order to use these delivery systems for oral administration of DDI to paediatric patients, strategies to improve the amount of DDI that could be loaded into the particles and to achieve high encapsulation efficiencies had to be developed. The limited solubility of DDI in lipid media was identified as a major factor that affected the loading capacity and encapsulation efficiency of DDI in the NLC. Therefore, a novel strategy aimed at increasing the saturation solubility of DDI in the lipid by attempting to increase the dissolution velocity of the drug in the lipid using a particle size reduction approach, was designed and investigated. DDI was dispersed in Transcutol® HP and the particle size of DDI in the liquid lipid medium was reduced gradually using hot high pressure homogenization and the product obtained from these studies was used to manufacture DDI-loaded NLC using a cold high pressure homogenization procedure. Although the encapsulation efficiency and drug loading following use of this approach was relatively high, the particles were large and showed a tendency to grow in size leading to the formation of microparticles after storage for two months at 25°C. In addition, the degree of crystallinity of the nanoparticles increased rapidly over the same storage period which led to expulsion of DDI nanoparticles for the NLC, despite the DDI loading in NLC being unaffected. It was clearly evident that this new approach of manufacturing solid lipid nanocarriers could be used as a platform not only for enhancing the loading capacity of DDI in solid lipid nanocarriers but also for other hydrophilic drugs. Differential protein adsorption patterns of DDI-loaded NLC were generated in vitro using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) in order to establish the potential for these systems to deliver DDI to the CNS. NLC formulations containing small amounts of DDI were used as these formulations showed a better stability profile than the formulation with a higher encapsulation efficiency and drug loading capacity. Furthermore, the encapsulation efficiency and drug loading of DDI were considered sufficient for use in 2-D PAGE studies. Data obtained from 2-D PAGE analysis reveal that DDI-loaded NLC preferentially adsorb proteins in vitro that are responsible for specific brain targeting in vivo. More importantly, these studies reveal that in addition to Tween® 80 that has already been shown to have the potential to target CDDS to the brain, Solutol® HS 15 has the potential to achieve a similar objective. Consequently, DDI-loaded NLC have the potential to deliver DDI to the brain and these results may be used as a platform for conducting in vivo studies to establish whether DDI can cross the blood brain barrier and enter the CNS when administered in NLC which may in turn lead to a major breakthrough in the management of HIV/AIDS and Aids Dementia Complex (ADC).