Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

As society draws closer to the post-antibiotic era and the pipeline for alternatives dries, there is an urgent need for the development of novel antimicrobial therapies that do not promote bacterial resistance, particularly for immunocompromised chronic wound patients. Antimicrobial peptides (AMPs), including human-derived LL37, show considerable promise as broad spectrum alternatives that also have wound healing properties; however, few have been clinically implemented as novel antimicrobials due to their cytotoxicity stemming from a poor understanding of their mechanisms and low stability in vivo. It has been suggested that tethering, or attaching AMPs onto surfaces, is a viable strategy of delivering bioactive AMPs to surfaces while reducing cytotoxicity and improving stability. Thus, we designed new chimeric versions of LL37 with collagen-binding domains (CBD), derived from collagenase (cCBD-LL37) and fibronectin (fCBD-LL37) for non-covalent tethering onto collagen, a prevalent biopolymer in commercially available wound dressings and scaffolds. Our overall hypothesis was that CBDs would mediate stable tethering of broadly active, non-cytotoxic CBD-LL37 onto collagen-based scaffolds. We first studied the loading, release and bioactivities (e.g. antimicrobial activity and cytotoxicity) of each CBD-LL37 on commercially available 100% collagen type I PURACOL® wound scaffolds. We found that both cCBD-LL37 and fCBD-LL37 bound highly to collagen, were active against relevant wound pathogens, demonstrated stable activity after 14 days of release, and were not cytotoxic to human fibroblasts. The addition of different CBDs onto LL37 also markedly altered their soluble bioactivities. Using similar methods, we then studied the loading, release and bioactivity of each CBD-LL37 on a commercially available FIBRACOL® wound scaffolds, comprised of 90% collagen type I and 10% calcium alginate biopolymers. We found that both cCBD-LL37 and fCBD-LL37 also bound highly to and retained on collagen for 14 days, but were only active against Gram-negative P. aeruginosa. This suggested that the presence other biopolymers in addition to collagen, which is common among commercial wound dressings, could cause significant differences in binding, retention and bioactivities of CBD-LL37. To better understand how CBD modification affected CBD-LL37 structure leading to different bioactivities, we studied the CBD sequence-, peptide structure-, concentration-, time-, and bilayer composition-dependent interactions of soluble CBD-LL37 and compared these findings with the properties of unmodified LL37. Using Molecular Dynamics (MD) simulations, circular dichroism (CD) spectroscopy, quartz crystal microbalance with dissipation (QCM-D), and fluorescent bilayer imaging we determined the structural basis behind CBD alterations in bioactivities. MD and CD, in addition to other intrinsic CBD properties (helicity, amphiphilicity, charge) we hypothesized that cCBD-LL37 utilized similar mechanisms as unmodified LL37 while fCBD-LL37 demonstrated based primarily on surface adsorption. We used QCM-D and Voigt-Kelvin viscoelastic modeling to determine the time- and concentration-dependent interactions of unmodified LL37 with model mammalian lipid bilayers, the mechanisms of which are still controversial in literature despite being widely studied. These results were used to propose a model for the interaction mechanism of LL37 with zwitterionic bilayers that aligned with its bioactive concentrations. LL37 adsorbed at concentrations where it is immunomodulatory until reaching a threshold which corresponded with its antimicrobial concentrations. The threshold was correlated to lipid bilayer saturation, after which LL37 formed transmembrane pores. We observed collapse of the bilayer into a rigid proteolipid film at concentrations higher than the reported cytotoxic threshold of LL37. The mechanistic and structural information for each CBD-LL37 and unmodified LL37 provided a baseline for QCM-D and Voigt-Kelvin viscoelastic modeling to further elucidate the time-, concentration-, lipid composition- and CBD sequence-dependent basis behind the observed bioactivities of cCBD-LL37 and fCBD-LL37. We found that similar to LL37, cCBD-LL37 demonstrated pore formation mechanisms likely due to their similar charges, structural content and amphiphilicity. fCBD-LL37 demonstrated time-dependent, adsorption-based mechanism likely due to its anchoring aromatic residues, low charge, and low amphiphilicity. Knowledge gained from this study allowed mechanistic predictions of two newly designed hypothetical CBD-LL37 peptides. Results from this study contribute to a better understanding of a new class of antimicrobial, non-cytotoxic therapies based on collagen-tethered CBD-LL37, bringing it closer to clinical implementation in chronic wound applications and demonstrate the viability of biopolymer tethering as a platform toward using AMPs to quench the resistance crisis.

Considerando a relevância dos trabalhos onde se utiliza eletrodos quimicamente modificados e o pequeno número de estudos envolvendo cocaína e seus interferentes (cafeína, teobromina e lidocaína), por técnicas eletroquímicas ou piezelétricas, este estudo tem como objetivo o desenvolvimento de eletrodos de ouro e platina quimicamente modificados com compostos da classe das cucurbiturilas (CB[5], CB[6] e CB[7]) para a detecção de cocaína. A técnica de microbalança de cristal de quartzo foi empregada a fim de se estudar cocaína padrão e seus interferentes, em fase gasosa. Os eletrodos de ouro foram quimicamente modificados com cucurbiturilas e o modificador CB[6] apresentou os melhores resultados. Medidas por voltametria cíclica foram realizadas utilizando-se um potenciostato Autolab III acoplado a um computador, com eletrodo de ouro e platina atuando como eletrodo de trabalho, Ag/AgCl como eletrodo de referência e eletrodo espiral de platina como eletrodo auxiliar, com velocidade de varredura de 0,1 V.s-1 (100 mV.s-1). Os parâmetros voltamétricos foram otimizados para tornar as análises mais rápidas e sensíveis sem perda de qualidade ou intensidade do sinal voltamétrico. O eletrodo de platina quimicamente modificado com filme de cucurbit[6]urila apresentou aumento da corrente de pico catódica quando estudado frente à cocaína, teobromina e lidocaína. Análises com eletrodo de platina sem modificador químico apresentaram limite de detecção de 4,14.10-6 mol.L-1 e limite de quantificação de 1,38.10-5 mol.L-1 , para a cocaína, e na presença do modificador químico CB[6] apresentou limite de detecção de 1,36.10-6 mol.L-1 e limite de quantificação de 4,54.10-6 mol.L-1 . Eletrodos de ouro com ou sem a presença de modificadores químicos não apresentaram sinal para nenhum analito. / Considering the importance of chemically modified electrodes and the small amount of the cocaine study and their interfering (caffeine, theobromine and lidocaine) using electrochemical and piezoelectric techniques, this study aims to investigate the development of the gold and platinum electrodes chemically modified by cucurbiturils (CB[5], CB[6] and, CB[7]) in order to detect cocaine. The Quartz Crystal Microbalance technique was employed in order to study in gas phase the standard samples of cocaine and their interfering. Gold electrode was chemically modified with cucurbiturils films and the CB[6] modifier showed the best results. The cyclic voltammetric measurements were performed using a Autolab III potentiostat coupled to a computer, being gold and platinum as the working electrode, Ag/AgCl as the reference electrode and platinum wire as counter electrode, using a scan rate of 0,1 V.s-1 (100 mV.s-1). The voltammetric parameters were optimized in order to make the analysis faster and more sensitive without loss of intensity and quality of the voltammetric signal. The platinum electrode modified by cucurbit[6]uril film showed an increase of cathodic current peak when electrode was exposed to cocaine, theobromine and lidocaine. Analysis employed platinum working electrode without chemical modifier showed a detection limit of 4.14 . 10-6 mol.L-1 and quantification limit of 1.38 . 10-5 mol.L-1 for cocaine and with chemical modifier CB[6] showed a detection limit of 1.36 . 10-6 mol.L-1 and quantification limit of 4.54 . 10-6 mol.L-1 . Gold electrodes with or without chemical modifiers showed no response for any analyte.

Dans cette thèse, nous proposons et démontrons un nouveau type de nanobiocapteur pour la détection de biomolécules à haute sensibilité et leur intégration à grande échelle (plaquette de 4 pouces). Le principe du nouveau nanobiocapteur électrique est basé sur la variation de conductivité électrique à travers des nano-îlots grâce au phénomène quantique appelé "blocage de Coulomb". Les nano-îlots de nickel (~5nm de diamètre) sont placés entre les nano-électrodes interdigitées (IND) (~45nm de largeur). La conductivité de ces dispositifs à Jonctions Tunnel Multiples (MTJ) est modifiée par l'adsorption de biomarqueurs impliqués dans la tumorogènese. Les oncologues ont récemment isolé et caractérisé un nouveau fragment d'anticorps à chaîne simple (scFv) qui reconnaît sélectivement la forme active de RhoA. Ce biomarqueur potentiel a été trouvé surexprimé dans diverses tumeurs. Les fragments d'anticorps ont été adsorbés, par des liaisons de coordination, sur les nano-îlots de nickel. Ces fragments sont capables de reconnaître spécifiquement la forme active de RhoA. Nous avons étudié ce biomarqueur et validé la chimie de surface à base de nano-'îlots de nickel pour la détection sans marquage, en utilisant une microbalance à quartz (QCM). Puis, nous avons mis au point et adapté à notre dispositif une méthodologie innovatrice pour réaliser, à l'échelle d'une plaquette, des microcanaux basés sur du photoPDMS. La caractérisation électrique finale des dispositifs intégrés a été testée en temps réel et à flux biologique continu. La forme active de RhoA a été détectée en discriminant la forme inactive. En annexe, je présente mon opinion épistémologique et éthique sur la nanotechnologie.

Fish oil is an excellent source of long chain polyunsaturated fatty acids (LC-PUFA), which can reduce the risk of cardiovascular disease in addition to other health benefits. However, the average intake of LC-PUFA in the Western diet is much lower than the recommended levels. Fish oil is prone to oxidative deterioration when exposed to oxygen and thus must be protected in order to be used in food products. Microencapsulation is one possibility that is already applied by the industry to protect fish oil. However, most of the conventional microencapsulation techniques suffer from shortcomings such as harsh processing conditions or the use of numerous chemicals. The main objective of this thesis was to develop a novel spray process to microencapsulate fish oil based on supercritical fluid (SCF) technology using supercritical carbon dioxide (SC-CO2) and CO2-expanded ethanol (CX EtOH). Fundamental physicochemical properties essential for optimal process design were lacking in the literature; therefore, density, interfacial tension (IFT) and viscosity of fish oil in the form of triglycerides and fatty acid ethyl esters were determined at different temperatures and pressures. Fish oil when equilibrated with SC-CO2 at elevated pressure expanded by up to about 40% in volume and increased in density by up to about 5%. Furthermore, IFT of fish oil in contact with SC-CO2 decreased substantially by an order of magnitude with an increase in CO2 pressure. When fish oil was in contact with CX EtOH, IFT decreased to ultra low levels at pressures of less than 10 MPa. Viscosity of fish oil equilibrated with SC-CO2 decreased substantially with pressure but increased with shear rate. Based on the physicochemical properties determined in this research, a novel process to produce micro- and nano-sized particles containing fish oil was developed based on a SCF spray-drying method. Key processing parameters have been evaluated and can be further optimized to improve encapsulation efficiency. Determination of physicochemical properties contributed to the fundamental understanding of the behavior of the fish oil+CO2 system with and without ethanol under high pressure conditions. The new microencapsulation process shows great potential for the delivery of bioactives in various product applications. / Bioresource and Food Engineering

Electrical double-layer formed at the interface between an electrode and an electrolyte has been a topic of innumerable studies. The electrical interface plays a crucial role in kinetics, mechanisms and applications in variety of electrochemical reactions. The electrical double-layer and electron-transfer reactions lead to many important applications of electrochemistry, which include energy storage devices, namely, batteries, fuel cells and supercapacitors. Electrochemical supercapacitors can withstand to higher power than batteries and deliver higher energy than the conventional electrostatic and electrolytic capacitors. A supercapacitor can be used as an auxiliary energy device along with a primary source such as a battery or a fuel cell for the purpose of power enhancement in short pulse applications. Among the various materials studied for electrochemical supercapacitors, carboneous materials, metal oxides and conducting polymers received attention. Among carboneous materials, various forms of carbon such as powders, woven cloths, felts, fibers, nanotubes etc., are frequently studied for electrochemical supercapacitors. Low cost, high porosity, higher surface area, high abundance and well established electrode fabrication technologies are the attractive features for using carboneous materials. However, specific capacitance (SC) of these materials is rather low. These electrodes store charge by electrostatic charge separation at the electrode/electrolyte interface. Electronically conducting polymers are interesting class of materials studied for supercapacitor application because of the following merits: high electronic conductivity, environmental friendliness, ease of preparation and fabrication, high stability, high capacitance and low cost. Polyaniline (PANI), polypyrrole and polythiophene are studied in this category. Transition metal oxides have attracted considerable attention as electrode materials for supercapacitors because of the following merits: variable oxidation state, good chemical and electrochemical stability, ease of preparation and handling. Hydrated RuO2 prepared by sol-gel process at low temperature has a specific capacitance as high as 720 F g-1 due to solid state pseudo faradaic reaction. However, high cost, low porosity and toxic nature limit commercialization of supercapacitors using this material. MnO2 is attractive as it is cheap, environmentally benign, its resources are abundant in nature and also it is widely used as a cathode material in batteries. An early study on capacitance behaviour of MnO2 was reported by Lee and Goodenough. Amorphous hydrous MnO2 synthesized by co-precipitation method exhibited rectangular cyclic voltammogram in various aqueous alkali salt solutions. A specific capacitance of 200 F g-1 was reported. Following this report, several reports appeared on capacitance characteristics of MnO2. According to the charge-storage mechanism reported, a specific capacitance of 1370 F g-1 is expected from MnO2. However, this value can be obtained in practice only when the mass of MnO2 is at the level of a few micrograms per cm2 area. At such a low thickness range, the utilization of the active material is high. As thin layers of MnO2 are uneconomical for practical capacitors, studies with a mass range of 0.4-0.5 mg cm-2 have been extensively reported. At this mass range, a maximum specific capacitance of about 240 F g-1 has been obtained. With an increase in mass per unit area, the specific capacitance of MnO2 decreases. The problem associated with low values of specific capacitance of thick layers of MnO2 is the following. The MnO2 deposits or coatings generally do not possess high porosity and the electrolyte cannot permeate into the coating. Only the outer layer of the electrode is exposed to the electrolyte. Consequently, the electrochemical utilization of the material decreases with an increase in thickness. Nevertheless, utilization of thick layers of the active materials is preferable for obtaining capacitance as high as possible in a given volume and area of the electrodes. Indeed, it would be ideal if specific capacitance of MnO2 is improved from its presently reported value of 240 F g-1 to a value equivalent to that of RuO2.xH2O, namely, 720 F g-1. In view of this, attempts are made to enhance specific capacitance of MnO2 by electrochemical deposition in presence of surfactants. Nanostructured MnO2 synthesized by inverse microemulsion route is also studied for electrochemical supercapacitors. The effect of crystallographic structure of MnO2 on the capacitance properties, studies on electrochemical deposition of MnO2 in acidic and neutral medium using electrochemical quartz crystal microbalance and capacitance characteristics of MnO2-polyaniline composites are also described in the thesis. Chapter 1 briefly discusses the importance of electrochemistry in energy storage and conversion, basics of electrochemical power sources, importance of MnO2, different synthetic procedures for MnO2 and its applications in energy storage and conversion in particular for electrochemical supercapacitors. Chapter 2 provides the experimental procedures and methodologies used for the studies reported in the thesis. In chapter 3, the effect of surface active agents, namely, sodium dodecyl sulphate (SDS) and Triton X-100 added to the electrolyte during electrodeposition of MnO2 on Ni substrate on capacitance properties is presented. Electrocrystallization studies show that MnO2 nucleates instantaneously under diffusion control and grows in three dimensions. The potentiodynamically prepared oxide provides higher specific capacitance than the potentiostatically and galvanostatically prepared oxides. Specific capacitance values of 310 and 355 F g-1 obtained for MnO2 electrodeposited in the presence of 100 mM SDS and 10 mM Triton X-100 are higher than the oxide electrodeposited in the absence of surfactants. Surfactant molecules adsorbed at the electrode/electrolyte interface alters structure of double-layer and kinetics of electrodeposition. Smaller particle size, greater porosity, higher specific surface area and higher efficiency of material utilization are the factors responsible for obtaining higher specific capacitance. Extended cycle-life studies indicate that the superior performance of MnO2 due to surfactants is present throughout the cycle-life tested. Chapter 4 pertains to electrochemical supercapacitor studies on nanostructured α-MnO2 synthesized by inverse microemulsion method and the effect of annealing. As synthesized nanoparticles of MnO2 was found to be in α-crystallographic structure with particles less than 50 nm size. Nanoparticles exhibited rectangular cyclic voltammograms between 0 and 1 V vs. SCE in aqueous 0.1 M Na2SO4 at sweep rates up to 100 mV s-1 due to the short diffusion path length. On annealing at different temperatures, a mixture of nanoparticles and nanorods with varying dimension is noticed. Specific capacitance of 297 F g-1 obtained during initial cycling decreases gradually on extended cycling. The capacitance loss is attributed to the increase in the resistance for intercalation/deintercalation of alkali cations into/from MnO2 lattice. MnO2 crystallizes into several crystallographic structures, namely, α-, β-, γ-, δ- and λ-structures. As these structures differ in the way MnO6 octahedra are interlinked, they possess tunnels or inter-layers with gaps of different magnitudes. Because capacitance properties are due to intercalation/deintercalation of protons or cations in MnO2, only some crystallographic structures, which possess sufficient gap to accommodate these ions, are expected to be useful for capacitance studies. The effect of crystal structure of MnO2 on its electrochemical capacitance properties is also included in chapter 4. Specific capacitance of MnO2 is found to depend strongly on the crystallographic structure, and it decreases in the following order: α ≅ δ > γ > λ > β. A specific capacitance value of 240 F g-1 is obtained for α-MnO2, whereas it is 9 F g-1 for β-MnO2. A wide (~ 4.6 Å) tunnel size and large surface area of α-MnO2 are ascribed as favorable factors for its high specific capacitance. A large interlayer separation (~7 Å) also facilitates insertion of cations in δ-MnO2 resulting in SC close to 236 F g-1. A narrow tunnel size (1.89 Å) does not allow intercalation of cations into β-MnO2. As a result, it provides very small SC. In Chapter 5, capacitance characteristics of PANI synthesized using (NH4)2S2O8, nanostructured MnO2 (α- and γ-form) and also PANI-MnO2 composites are presented. Morphology of PANI synthesized resembles the morphology of the MnO2 used as the oxidant. Electrochemical capacitance properties of PANI and composites are studied in a mixed electrolyte of 0.1 M HClO4 and 0.3 M NaClO4 between 0 and 0.75 V vs. SCE. Specific capacitance of 394 F g-1 is obtained for PANI synthesized using γ-MnO2. Chapter 6 describes the electrocatalytic behaviour of Mn3[Fe(CN)6]2 synthesized by ion-exchange reaction between MnSO4 and K3[Fe(CN)6] and the effect of annealing on its electrochemical capacitance properties. As prepared Mn3[Fe(CN)6]2 and also the sample heated at 100 oC exhibit redox couple in 0.1 M Na2SO4 electrolyte, corresponding to Fe(CN)64-/Fe(CN)63- present in the matrix. Mn3[Fe(CN)6]2 samples annealed at 150 oC and above decompose to oxides of manganese and iron, and hence exhibit capacitance characteristics in 0.1 M Na2SO4 electrolyte. A maximum specific capacitance of 129 F g-1 is obtained for Mn3[Fe(CN)6]2 annealed at 300 oC. Electrochemical quartz crystal microbalance (EQCM) investigations of kinetics of electrodeposition of MnO2 in acidic and neutral media, and capacitance behaviour are presented in chapter 7. Oxidation of Mn2+ to MnO2 is characterized by an anodic cyclic voltammetric peak both in acidic and neutral media. During the reverse sweep, however, reduction of MnO2 into Mn2+ occurs in two steps in the acidic medium and in a single step in the neutral medium. From EQCM data of mass variation during cycling, it is observed that the rate of electrodeposition of MnO2 is higher in the neutral medium than in the acidic medium. Specific capacitance of MnO2 deposited from the neutral medium is higher than that deposited from acidic medium owing to different crystallographic structures. Reversible insertion/deinsertion of hydrogen in to the layers of δ-MnO2 is observed in hydrogen evolution region. Details of the above studies are described in the thesis.

This thesis details the development of expertise and tools required for the study of amino acids deposited on Au(111), with a primary focus on the design and testing of a Knudsen cell for controlled deposition of L-cysteine and L-methionine. An ultra-high vacuum preparation chamber designed by Dr. Katie Mitchell and built by Torrovap Industries Inc. was installed. This chamber is connected to the existing scanning tunneling microscopy chamber via a gate valve, and both chambers can operate independently. Various instruments such as a mass spectrometer, quartz crystal microbalance, ion source, and sample manipulator were installed on the preparation chamber. Scanning tunneling microscopy was performed on both homemade and commercial Au(111) thin films. High resolution images of "herringbone" reconstruction and individual atoms were obtained on the commercial thin films, and optimal tunneling conditions were determined. A Knudsen cell was designed to be mounted on the preparation chamber. The Knudsen cell operates over the temperature range 300-400K, with temperatures reproducible to ±0.5K, and stable to ±0.1K over a five minute period. Reproducible deposition rates of less than 0.2Ǻ/s were obtained for both L-cysteine and L-methionine. Electron impact mass spectrometry and heat of sublimation measurements were performed to characterize the effusion of L-cysteine and L-methionine from the Knudsen cell. The mass spectrometry results suggest that L-cysteine was decomposing at 403K while L-methionine was stable during effusion. Heats of sublimation of 168.3±33.2kJ/mol and 156.5±10.1kJ/mol were obtained for L-cysteine and L-methionine respectively.

One the most daunting technical challenges in the realization of biosensors is functionalizing transducing surfaces for the detection of biomolecules. Functionalization is defined as the formation of a bio-compatible interface on the transducing surfaces of bio-chemical sensors for immobilizing and subsequent sensing of biomolecules. The kinetics of functionalization reactions is a particularly important issue, since conventional functionalization protocols are associated with lengthy process times, from hours to days. The objective of this thesis is the improvement of the functionalization protocols and their kinetics for biosensing applications. This objective is realized via modeling and experimental verification of novel functionalization techniques in microfluidic environments. The improved functionalization protocols using microfluidic environments enable in-situ functionalization, which reduces the processing times and the amount of reagents consumed, compared to conventional methods. The functionalization is performed using self-assembled monolayers (SAMs) of thiols. The thiols are organic compounds with a sulphur group that assists in the chemisorption of the thiol to the surface of metals like gold. The two reactions in the functionalization process examined in this thesis are the SAM formation and the SAM/probe molecule conjugation. SAM/probe molecule conjugation is the chemical treatment of the SAM followed by the binding of the probe molecule to the SAM. In general, the probe molecule is selective in binding with a given biomolecule, called the target molecule. Within this thesis, the probe molecule is an antibody and the target molecule is an antigen. The kinetics of the reaction between the probe (antibody) and the target biomolecule (antigen) is also studied. The reaction between an antigen and its antibody is called the immunoreaction. The biosensing technique that utilizes the immunoreaction is immunoassay. A numerical model is constructed using the finite element method (FEM), and is used to study the kinetics of the functionalization reactions. The aim of the kinetic studies is to achieve both minimal process times and reagents consumption. The impact of several important parameters on the kinetics of the reactions is investigated, and the trends observed are explained using kinetic descriptive dimensionless numbers, such as the Damköhler number and the Peclet number. Careful numerical modeling of the reactions contributes to a number of findings. A considerably faster than conventional SAM formation protocol is predicted. This fast-SAM protocol is capable of reducing the process times from the conventional 24-hours to 15 minutes. The numerical simulations also predict that conventional conjugation protocols result in the overexposure of the SAM and the probe molecule to the conjugation reagents. This overexposure consequently lowers conjugation efficiencies. The immunoreaction kinetics of a 70 kilo-Dalton heat shock protein (HSP70) with its antibody in a hypothetical microchannel is also investigated through the FEM simulations. Optimal reaction conditions are determined, including the flow velocity and the surface concentration of the immobilized probes (antibodies). Based on the numerical results and a series of experimental studies, the fast-SAM protocol application is successfully confirmed. Moreover, the optimum reagent concentration for a given one- hour conjugation process time is determined. This functionalization protocol is successfully applied to immobilize the HSP70 antibody on gold surfaces. The use of the fast-SAM protocol and the predicted optimum conjugation conditions result in binding of the HSP70 antibody on gold, with the same or superior immobilization quality, compared to the conventional protocols. Upon implementation of a 70 μm.s^(-1) flow velocity, the reaction is observed to complete in around 30-35 minutes, which is close to the numerically predicted 30 minutes and 16 seconds. This immunoreaction time is considerably less than conventional 4-12 hour processes. The modified in-situ functionalization techniques achieved here are promising for substantially reducing the preparation times and improving the performance of biosensors, in general, and immunoassays, in particular.

This thesis describes a number of novel experiments contributing to the understanding of protein adsorption from both a fundamental and applied perspective. The first three papers involve the use of the localized surface plasmon resonance of gold nanospheres to measure protein conformational dependencies during heat and acid denaturation. Thermal denaturation of BSA is shown to proceed differently depending on the size of nanosphere to which it is conjugated. Activation energies are extracted for thermal denaturing on nanoparticles. These energies decrease with decreasing radius of curvature. Under pH perturbation in the acid region, the multiple transition states of bulk BSA are suppressed, and only one apparent transition around pH 4 is evident. Smaller spheres (diameter < 20nm) do not exhibit any transition. A significant finding of all three studies is that the state and stability of BSA depends strongly upon local curvature. The last two papers investigate protein adsorption relevant to the biomaterial field. Investigation of protein adsorption to polyHEMA hydrogels is carried out using a quartz crystal microbalance. Single and mixed protein adsorption kinetics for BSA, lysozyme and lactoferrin are extracted and interpreted. Selected commercial cleaning solutions are shown to be no more effective than simple buffer solution. Examination of commercial lenses indicates that the morphology of adsorption is material dependent and that siloxane-based hydrogels only deposit low levels of protein. A unique fibril-like morphology is identified on galyfilcon A. Protein morphology is discussed in terms of bare lens morphology, roughness, and surface composition.

This thesis describes a number of novel experiments contributing to the understanding of protein adsorption from both a fundamental and applied perspective. The first three papers involve the use of the localized surface plasmon resonance of gold nanospheres to measure protein conformational dependencies during heat and acid denaturation. Thermal denaturation of BSA is shown to proceed differently depending on the size of nanosphere to which it is conjugated. Activation energies are extracted for thermal denaturing on nanoparticles. These energies decrease with decreasing radius of curvature. Under pH perturbation in the acid region, the multiple transition states of bulk BSA are suppressed, and only one apparent transition around pH 4 is evident. Smaller spheres (diameter < 20nm) do not exhibit any transition. A significant finding of all three studies is that the state and stability of BSA depends strongly upon local curvature. The last two papers investigate protein adsorption relevant to the biomaterial field. Investigation of protein adsorption to polyHEMA hydrogels is carried out using a quartz crystal microbalance. Single and mixed protein adsorption kinetics for BSA, lysozyme and lactoferrin are extracted and interpreted. Selected commercial cleaning solutions are shown to be no more effective than simple buffer solution. Examination of commercial lenses indicates that the morphology of adsorption is material dependent and that siloxane-based hydrogels only deposit low levels of protein. A unique fibril-like morphology is identified on galyfilcon A. Protein morphology is discussed in terms of bare lens morphology, roughness, and surface composition.