Functionalized membranes provide an elegant platform for selective separations and sorptions. In this dissertation, application of functionalized membranes for surfactant and metal sorption studies are discussed. Sorption behavior of surfactants is also studied using quartz crystal microbalance (QCM) and other techniques. Adsorption of the ethoxylated surfactants on polymeric materials (cotton and polyester) and model gold surface was quantified from a non-aqueous siloxane based solvent (D5) and water. The role of ethylene oxide group and the effect of nature of polymeric materials on adsorption behavior was quantified and established. In the case of gold-water interface, the adsorption data was fitted to calculate adsorption/desorption rate constants. The study is important towards applications involving use of the surfactants in cleaning operations. PAA functionalized membranes were prepared and used for separation of the surfactants from the siloxane solvent. Finally the pH sensitivity of the PAA-surfactant complex was verified by successful regeneration of the membrane on permeation of slightly alkaline water. The preparation and application of thiol and sulfonic acid functionalized silica mixed matrix membranes for aqueous phase metal ion sorption is also studied. The functionalized particles were used as the dispersed phase in the polysulfone or cellulose acetate polymer matrix. The effects of the silica properties such as particle size, specific surface area, and porous/nonporous morphology on the metal ion sorption capacity were studied. Silver and ferrous ions were studied for metal sorption capacities. The ferrous ions were further reduced to prepare membrane immobilized iron nanoparticles which are attractive for catalytic applications. One dimensional unsteady state model with overall volumetric mass transfer coefficient was developed to model the metal ion sorption using mixed matrix membrane. The study demonstrates successful application of the functionalized mixed matrix membranes for aqueous phase metal capture with high capacity at low transmembrane pressures. The technique can be easily extended to other applications by altering the functionalized groups on the silica particles. The study is important towards water treatment applications and preparation of membrane immobilized metal nanoparticles for catalytic applications.

A técnica de Microbalança de Cristal de Quartzo (QCM) tem sido utilizada para a aplicação em biossensores. Esta técnica consiste no monitoramento da freqüência de oscilação do cristal de quartzo e a variação de freqüência está relacionada com a variação de massa na superfície do cristal por meio da equação de Sauerbrey. Porém, sabe-se que há discrepância entre a massa calculada pela equação de Sauerbrey e a massa real aderida na superfície do cristal de quartzo, sendo tal discrepância causada por fatores tais como a viscoelasticidade, o que é especialmente observado para macromoléculas e sistemas biológicos. Com a técnica de Admitância Eletroacústica (AE) é possível analisar a massa real devido à análise em separado dos parâmetros que compõem o circuito equivalente do cristal de quartzo e também inferir informações sobre a estrutura das monocamadas montadas sobre a superfície do cristal de quartzo. Neste trabalho foi utilizada técnica de AE para se potencializar e detalhar o estudo da formação de monocamadas automontadas e interações entre diferentes proteínas e carboidratos. Em muitos casos verificou-se que durante a formação de determinadas monocamadas, grande parte da variação de massa estava relacionada a interações fracas e não-específicas. Também durante a formação das monocamadas de tióis de cistamina, verificou-se que a estrutura da monocamada é extremamente dependente das concentrações iniciais de cistamina utilizadas para formar a monocamada. As interações entre proteínas e carboidratos foram realizadas após formação de multicamadas nas quais as proteínas eram imobilizadas para depois estudar-se, então, sua interação com carboidratos específicos. No caso da Jacalina, um tipo de lectina, observou-se interações bastante específicas com a fetuína e interações fracas com a alfa-lactose. A atividade da enzima GumH também foi testada com sucesso utilizando a técnica de AE. / The Quartz Crystal Microbalance (QCM) has been largely used for biosensor applications. This technique consists on monitoring quartz crystal oscillation frequency. The relationship of quartz crystal frequency variation with mass deposited on the crystal surface is described by Sauerbrey´s equation. However, the relationship is not directly inferred and discrepancy exists caused mainly by viscoelasticity features of mass adsorbed on the quartz crystal surface. The viscoelastic influence is very common to be observed especially for macro-molecules and biological systems. By using Electroacoustic Admittance (EA) technique it is possible to calculate and separate the real mass deposited over the quartz crystal from other contributions. Therefore, the EA was used to infer about self-assembly monolayer structure being deposited over the quartz crystal. In this work EA technique was used to study details of self-assembled monolayer formation and specific interactions between different proteins and carbohydrate molecules. It was observed that during monolayer formation the majority of mass variation was related to non-specific interactions. For instance, regarding cystamine monolayer formation it was observed that the monolayer structure is dependent on the cystamine concentrations in the liquid medium. The study of interactions between proteins and carbohydrates was conducted by means of multilayers approach in which the proteins are immobilized previously to study the interaction between its active sites and carbohydrates. In the specific case of Jacalin, a type of lectin, it was observed a large formation of specific bonding between this protein and alpha-lactose or fetuin. The GumH enzyme activity was also tested successfully by using of EA technique.

A deposição em regime de subtensão (DRS) de cádmio e chumbo foi estudada sobre ouro e filmes de selênio em meio ácido. Os estudos foram realizados utilizando a voltametria cíclica (VC) e a microbalança eletroquímica de cristal de quartzo (MECQ). Foi observado que o cádmio e o chumbo se depositam de formas diferentes sobre ouro e sobre os filmes de selênio. O cádmio quando depositado sobre o eletrodo de ouro ocupa um átomo de ouro por ad-átomo, fornecendo uma carga associada à formação da monocamada adsorvida de aproximadamente 42 µC cm-2, que corresponde a um recobrimento de 0,15 monocamadas. Os resultados com a MECQ mostraram que a deposição em regime de subtensão do Cd ocorre com uma forte presença da adsorção de ânions perclorato e bissulfato. A DRS de cádmio sobre os filmes de selênio ocorre de maneira semelhante a que foi observada sobre o eletrodo de ouro, porém a carga total da monocamada adsorvida foi de 195,7 µC cm-2, que é um pouco maior do que a carga total para a formação de uma monocamada de selênio sobre ouro. Além disso, foi observado que o cádmio difunde no filme de selênio, e que a co-adsorção de ânions e água durante a formação da monocamada de cádmio foi negligenciável. O ad-átomo de chumbo ocupa dois átomos de ouro e a carga de formação da monocamada é atribuída a contribuições de dois picos relacionados com a DRS. O recobrimento máximo chega a 0,3 monocamadas de chumbo sobre ouro, com a deposição do tipo loosely packed. O processo de DRS sobre os filmes de selênio ocorre com a formação de um único pico. A formação do segundo pico sofre interferência da formação de H2Se que ocorre na superfície do filme de selênio e modifica o tipo de empacotamento dos ad-átomos de chumbo sobre o substrato eletródico. O recobrimento obtido com a DRS foi de 0,7 monocamadas de chumbo sobre selênio. A co-adsorção de ânions e água foi constante, tanto em estudos sobre o eletrodo de ouro, como sobre os filmes de selênio. O estudo das propriedades dos filmes de selênio modificados por ad-átomos de cádmio e chumbo foi efetuado por medidas de cronoamperometria para altos tempos de polarização. Foi observado que o cádmio difunde para a fase do filme de selênio, em função do seu alto coeficiente de difusão no estado sólido, formando o composto CdSe. Por outro lado, este processo de difusão não foi observado para o chumbo, não havendo evidências de formação do composto PbSe. A combinação da voltametria cíclica com a microbalança eletroquímica de cristal de quartzo possibilitou acompanhar as mudanças nos mecanismos de formação de monocamadas de cádmio e chumbo em potenciais de subtensão, assim como a inibição da formação do H2Se. Este último efeito foi marcante na DRS de chumbo, onde foi alterada a forma de empacotamento do ad-átomo na superfície. / Cd and Pb underpotential deposition (UPD) on gold electrode and selenium thin film, from acid media, were studied using cyclic voltammetry (CV) and electrochemical quartz crystal microbalance (EQCM). Different form of deposition for cadmium and lead were observed on gold electrode and selenium thin film. The presence of one peak in the positive sweep with a total charge density value between 42 60 µC cm-2 was observed from the results obtained for Cd upd on Au. This result is attributed to a covering of 0.15 0.20 Cd monolayer on gold electrode with the occupation of one active site by each Cd ad-atom. EQCM results suggest a large increase in mass upon Cd upd, which appears to result from co-adsorbed perchlorate and bisulfate anions. The upd of cadmium on the selenium films were similar to the observed on the gold electrode; however with a higher associated charge of 196 µC cm-2. Moreover, the cadmium upd process on selenium is accompanied by the diffusion of cadmium into the bulk of Selenium films. Also, the co-adsorption of anions and water during cadmium deposition on Selenium films were negligenceable. The UPD process of Pb ad-atoms on gold electrodes occurs with the occupation of two gold atoms for ad-atom ones. Two electrochemical processes are observed and the charge values were conferred a low covering the 0.3 monolayer, with a wrapping up of the type loosely packed. The co-adsorption of perchlorate anions and water were observed during UPD process. The UPD process of Pb ad-atoms on the selenium films is complex, and the formation of H2Se modifies the type of wrapping up of lead ad-atoms on the electrode surface. In this case, that the gotten covering were 0.7 monolayer of lead on selenium, were observed the co-adsorption of anions and water in this UPD process. During the studies carried through for cronoamperometry in high times of polarization (UPD potentials) on the Se films were observed that the cadmium spreads out for the phase of the selenium film. This phenomenon occurs due to the high coefficient of diffusion in the solid state of the Cd, allowing the formation of the CdSe. On the other hand, this process of diffusion was not so evident for the lead, that presents a low coefficient of diffusion in the solid state, and thus, do not support the formation of PbSe. The UPD studies by cyclic voltammetry combined with electrochemical quartz crystal microbalance measurements allowed to observe the changes in the monolayers formation mechanisms of cadmium and lead, as well as the inhibition of H2Se formation. This effect was found in the lead UPD, where was modified the form of packing up of the adatom in the surface.

Abstract This thesis describes the design, fabrication and operation of a microfluidic device for the screening of biomolecule mixture surface mediated effects. The characterisation of a surface immobilisation strategy that will allow the robust attachment of candidate biomolecules on a substrate for use in cell culture applications. This is carried out in the form of a modified and optimised layer-by-layer surface immobilisation strategy and its subsequent thorough and robust characterisation. This was achieved by compiling and critically analysing large amounts of quartz crystal microbalance with dissipation (QCM-D) data and the model utilised to provide meaningful, physical data as an output. QCM-D data was combined with surface plasmon resonance (SPR) data to validate the assumptions used within the QCM-D model package. Further evidence demonstrating the presence of the multilayer, as described by QCM-D and SPR, is achieved using x-ray photoelectron spectroscopy (XPS). These results show that the multilayer surface is robustly attached to the substrate and consists of a large amount of water whilst being able to immobilise mixtures of four proteins. A custom protocol for fabricating these two layer devices was devised and is presented. Scale limitations have been overcome to provide mixing capabilities for large extracellular matrix molecules to be immobilised on the previously described, microfluidically generated surface immobilisation strategy. The optimisation and characterisation of the mixing within this microfluidic device, affected by the incorporated staggered herring bone mixer is also shown. Using dynamic force spectroscopy (DFS) along with a custom designed force curve data processing and analysis package, the spatial localisation of a mixture of four immobilised biomolecules was determined. The aim of this study was to compare the spatial localization of a mixture of four biomolecules created by; standard cell culture protocols (adsorbed from bulk onto tissue culture polystyrene) and a surface created via microfluidic deposition on top of a previously described surface immobilisation strategy. The design and robust application of this custom analysis package allows the definition of a “Barricade of Specificity” such that interactions between an antibody functionalised AFM tip and a surface composed of a mixture of proteins, to be categorised as either a “true” specific interaction, or a non-specific interaction. The application of this Barricade of Specificity thus allows the spatial localisation of four immobilized biomolecules to be determined with a large degree of accuracy as a result of the large rage of non-specific interactions surveyed and the strict definition of a valid rupture force. The final chapter details the application of the microfluidic platform to enable high throughput screening of the effects of extracellular matrix (ECM) molecules, singly and in combination, with regards to the effect on the expression of cell surface markers on umbilical cord blood (UCB) derived CD34+ cells. Careful selection of candidate ECM molecules, cytokine and oxygen concentration has resulted in little difference in the effect on UCB derived CD34+ cells differentiation state after seven days in culture. The major effect has been the maturation towards lymphocyte and leukocyte precursors. However, of the four ECM molecules tested individually, in binary and in quaternary combinations, osteopontin (Opn) and laminin (Ln) demonstrated differences compared to other surfaces tested. In order to further assess the effect of these protein surfaces on the cell surface marker expression of UCB derived CD34+ cells, further tests are warranted for increased periods of time to enable greater discrimination in marker expression and thus increase our understanding of the fundamental biology of this rare and clinically useful cell source.

This thesis concerns the development of surface ligation techniques for the preparation of carbohydrate biosensors. Several methodologies were developed based on efficient photochemical insertion reactions which quickly functionalize polymeric materials, with either carbohydrates or functional groups such as alkynes or alkenes. The alkyne/alkene surfaces were then treated with carbohydrate azides or thiols and reacted under chemoselective Cu-catalyzed azide-alkyne cycloaddition (CuAAC) or photo-radical thiol-ene/yne click chemistry, thus creating a range of carbohydrate biosensor surfaces under ambient conditions. The methodologies were evaluated by quartz crystal microbalance (QCM) and surface plasmon resonance (SPR) flow through instrumentations with recurring injections of a range of lectins, allowing for real-time analysis of the surface interactions. The developed methods were proven robust and versatile, and the generated carbohydrate biosensors showed high specificities and good capacities for lectin binding.  The methods were then used to investigate how varying the glycan linker length and/or a sulfur-linkage affect the subsequent protein binding. The survey was further explored by investigating the impact of sulfur in glycosidic linkages on protein binding, through competition assays with various O/S-linked disaccharides in solution interactions with lectins. / QC 20120309

A fundamental characterization of hexafluoroalcohol substituted polynorbornene (HFAPNB) was completed to improve the final photoresist formulation using these materials. In this work, it was found that the dissolution behavior of these materials was controlled by the ability of polymer chains to form hydrogen bonds. This ability to form interchain hydrogen bonds was affected by stereochemical changes in the polynorbornene backbone as molecular weights increase. These observed changes in backbone polynorbornene stereochemistry were accurately modeled using the "helix-kink" theory, first described by Ahmed and Ludovice. It was found that several material properties altered the interchain hydrogen bonding within these materials, such as the polydispersity, polymerization catalyst, and the polymer film thickness. However, none of these material properties altered the unusual dissolution behavior observed in these materials. To improve the potential formulation of these materials, the interactions between HFAPNB and resist additives were studied. For all tested photoacid generators, it was found that some interchain hydrogen bonding occurred between resist additive molecules and HFA side groups, which retarded the dissolution rate in the formulated material. In particular, one can create a simple resist using unprotected HFAPNB polymer with an iodonium photoacid generator. Finally, a series of norbornene oligomers were evaluated as potential dissolution inhibitors for HFAPNB. It was found that the dissolution rate of HFAPNB can be completely inhibited with dissolution inhibitors at a loading of 15%.

Area selective atomic layer deposition (ASALD) is demonstrated to be a promising route to perform direct patterned deposition. In particular, methods to modify (or mask) the surface and process parameters to perform selective deposition of titanium dioxide have been developed and investigated in detail. Results indicated that self assembled monolayer based masking methodology posses significant limitations due to challenges associated with obtaining defect free monolayer and absence of traditional patterning techniques. On the other hand, polymer films based masking methodology offer a better alternative to perform ASALD. A number of factors that must be considered in designing a successful ASALD process based on polymer films were identified. These include: reactivity of polymer with ALD precursor, diffusion of ALD precursors through polymer mask and remnant precursor content in the polymer film during ALD cycling. Investigations suggested that ALD nucleation can be successfully blocked on polymer films that do not contain direct OH sites in their backbone. It was observed that sorption of water in the polymer film does not pose a serious limitation however; metal precursor diffusion through the polymer mask was identified as a critical parameter in determining the minimum required masking layer thickness for a successful ASALD process. In addition, a novel ASALD-based top surface imaging (TSI) technique has been developed. The ASALD-TSI process has demonstrated sharp contrast (etch barrier deposition vs exposure dose) and therefore offers the potential to overcome many of the challenges experienced with conventional TSI schemes.

In this study, we have investigated the effect of substrate temperature, use of adhesive layer, deposition rate, annealing and substrate prebaking on the morphology of gold films deposited onto quartz surfaces. For the film growth, physical vapor deposition methods namely electron beam and thermal depositions have been used. Surface morphology of the films have been characterized with atomic force microscopy. Our aim was to confirm the general trends observed for these parameters in our evaporator system for a limited working range in order to produce gold films which are suitable to be used simultaneously for quartz crystal microbalance and helium atom diffraction measurements. At the end of this study, we confirmed the general trends regarding the effect of these parameters stated in literature except annealing process. We obtained a minimum 170 nm2 atomically flat surface with a roughness value smaller than 0.200 nm by thermal deposition method.

<p>Dynamic Combinatorial Chemistry (DCC) is a recently introduced supramolecular approach to generate dynamically interchanging libraries of compounds. These libraries are made of different building blocks that reversibly interact with one another and spontaneously assemble to encompass all possible combinations. If a target molecule, for instance a receptor is added to the system and one or more molecules show affinity to the target species, these compounds will, according to Le Châtelier´s principle, be amplified on the expense of the other non-bonding constituents. To date, only a handful of different systems and formats have been used. Hence, to further advance the technique, especially when biological systems are targeted, new reaction types and new screening methods are necessary. This thesis describes the development of reversible sulfur reactions, thiol/disulfide interchange and transthiolesterification (the latter being a new reaction type for DCC), as means of generating reversible covalent bond reactions. Two different types of target proteins are used, enzymes belonging to the hydrolase family and the plant lectin Concanavalin A. Furthermore, two new screening/analysis methods not previously used in DCC are also presented; the quartz crystal microbalance (QCM)-technique and catalytic self-screening.</p>

Crystallization of water or water-encaged gas molecules occurs when nuclei reach a critical size. Certain antifreeze proteins (AFPs) can inhibit the growth of both of these, with most representations conceiving of an embryonic crystal with AFPs adsorbing to a preferred face, resulting in a higher kinetic barrier for molecule addition. We have examined AFP-mediated inhibition of ice and clathrate hydrate crystallization, and these observations can be both explained and modeled using this mechanism for AFP action. However, the remarkable ability of AFPs to eliminate „memory effect‟ (ME) or the faster reformation of clathrate hydrates after melting, prompted us to examine heterogeneous nucleation. The ubiquitous impurity, silica, served as a model nucleator hydrophilic surface. Quartz crystal microbalance-dissipation (QCM-D) experiments indicated that an active AFP was tightly adsorbed to the silica surface. In contrast, polyvinylpyrrolidone (PVP) and polyvinylcaprolactam (PVCap), two commercial hydrate kinetic inhibitors that do not eliminate ME, were not so tightly adsorbed. Significantly, a mutant AFP (with no activity toward ice) inhibited THF hydrate growth, but not ME. QCM-D analysis showed that adsorption of the mutant AFP was more similar to PVCap than the active AFP. Thus, although there is no evidence for „memory‟ in ice reformation, and the structures of ice and clathrate hydrate are distinct, the crystallization of ice and hydrates, and the elimination of the more rapid recrystallization of hydrates, can be mediated by the same proteins.