Philosophiae Doctor - PhD / Carbon dioxide emissions have become a major concern as they are one of the contributing factors to the “green-house” effect. Recently, much effort has been put into separating carbon dioxide (CO2) from flue gases linked to the combustion processes at fixed point sources. The development of solid sorbents for adsorption based on CO2 capture has attracted much attention. Ordered Mesoporous Silica (OMS) materials have recently attracted much attention as solid adsorbents for capturing CO2. OMS have been investigated for this purpose owing to their high pore volume, large surface area and ease of functionalizationIn this work we report on the synthesis of OMS viz. MCM-41 and SBA-15 along with amorphous silica as adsorbents for CO2 capture. MCM-41 was prepared with surfactants having different alkyl chain lengths (C14TABr, C16TABr and C18TABr) where TABr is trimethylammonium bromide. SBA-15 was prepared using a Triblock copolymer as a structure directing agent for the organization of polymerizing silica species. Commercial amorphous silica gel was used for comparative purposes. Initial characterization OMS with powder X-Ray diffraction (XRD) and small angle diffraction (SAXS) yielded diffraction patterns which may be associated with well-ordered structures of hexagonal mesoporous material. Ease of preparation for MCM-41 materials allowed for convenient scale- up, obtaining highly ordered mesoporous silica MCM-41 at room temperature. SBA-15 was also found to be scaled up with considerable ease through increasing the volume of the autoclave during hydrothermal treatment. Structural, morphological and textural properties of the adsorbents were characterized by N2 physisorption measurements, Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM) and Thermogravimetric Analysis (TGA). TEM confirmed the hexagonal structure; SEM showed that C14MCM-41 had spheroidal particle morphology whereas SBA-15 displayed rod-like structures. High surface areas of up to 1302, 1186, 1211 and 1024 m2/g for C14MCM-41, C16MCM-41, C18MCM-41 and SBA-15, respectively were obtained. The pore size of MCM-41 materials was increased from 2.6 nm for C14MCM-41 to 4.4 nm in diameter for C18MCM-41 using surfactants with different alkyl chain lengths. CO2 adsorption characteristics of OMS were studied using CO2-temperature programmed desorption (TPD). The results showed that C14MCM-41, C16MCM- 41, C18MCM-41 and SBA-15 desorbed 0.19, 0.16, 0.11 and 0.26 mmol/g respectively. The synthesized OMS were then further modified by grafting various amine moieties on their surfaces in order to increase their CO2 adsorptive capabilities. 3-(Aminopropyl)triethoxysilane (APS), N-[3-(trimethoxysilyl)propyl]ethylene- diamine (TPED), 3-chloropropyl)-trimethoxysilane (CPS), ethyl 2-bromopropanoate, tris(2-aminoethyl)amine (TREN) and guanidine. Several characterization techniques such as XRD, SAXS, HRTEM, HRSEM, TGA, Fourier Transform Infra-Red (FT-IR) spectroscopy, CO2 isotherms and CO2-TPD were used to analyze amine grafted solid sorbents for CO2 capture. The results revealed that the structural integrity of the amine modified sorbents was not compromised during the grafting process. The structural properties of the supports, such as surface area and pore size, nature of amine and the number of amine groups, affected the loading and CO2 adsorption capacity of chemically grafted sorbents. APS grafted amorphous silica gel adsorbed 0.67 mmol/g CO2, which proved to be the highest compared to C18MCM-41 and SBA-15 grafted with APS and TPED. C18MCM-41, SBA-15 and amorphous silica gel were also grafted with TREN and adsorbed 0.42, 0.51 and 0.27 mmol/g of CO2, respectively. A systematic study of guanidine grafted on C14MCM-41, C16MCM-41 and C18MCM-41 was investigated, for the first time, to the best of our knowledge. Structural properties like variation in pore size, proved to enhance the adsorption capacity of the adsorbent, coupled with the guanidine molecules grafted on MCM-41 materials. C18MCM-41-guanidine showed the highest CO2 uptake of the guanidine grafted MCM-41 materials, adsorbing 0.30 mmol/g. A novel synthetic route to TPED-TREN grafted C18MCM-41 and SBA-15, using ethyl 2-bromopropanoate as a linker, was investigated as a potential adsorbent for CO2 capture, for the first time. C18MCM-41-TPED-TREN and SBA-15-TPED-TREN CO2 adsorption capacity were found to be 0.14 and 0.14 mmol/g, respectively.

The objective of this work was to synthesize functionalized mesoporous silsesquioxanes with high concentrations of amine groups. During typical sol-gel syntheses, these materials are obtained by co-condensation of organic precursors with suitable linkers, such as tetraethoxysilane, necessary to prevent the mesoporous structure from collapsing. Thus, concentrations of amine groups in organosilicas usually do not exceed 2.7-3.4 mmol g -1. The use of bridged bis-trimethoxysilanes, however, allowed formation of mesoporous materials with no linker. Polycondensation of bis-trimethoxysilanes containing amine groups was conducted in acidic, neutral and basic media, resulting in high yields of solid bridged silsesquioxanes. Gelation occurred quickly if no acid or base was added to the reaction mixture. The hybrid organic/ inorganic nature of obtained materials was confirmed by FT-IR and MAS CP NMR spectroscopy. Elemental analysis showed that amino group concentration in the products was 3.3-4.1 mmol g -1. Measurement of particle size distribution confirmed that choice of reaction media significantly affects particle sizes and agglomeration degrees, with the largest agglomerates (up to 50 μm) formed in basic media. A morphology study, using smallangle X-Ray scattering, displayed two-level fractal structures composed of aggregated 6.5-10.5 nm particles. Reactions in the presence of a surfactant resulted in formation of mesoporous structures. Furthermore, the obtained bridged silsesquioxanes were thermally stable down to 260 °C, but could reversibly absorb water and CO 2 at temperatures below 120 °C. Thus, condensation of the bridged precursor without a linker resulted in formation of a highly functionalized mesoporous material.

<p>Proteins fold into well-defined three-dimensional structures to carry out their biological functions which involve non-covalent interactions with other cellular molecules. Knowledge about the thermodynamic properties of proteins and protein-ligand complexes is essential for answering fundamental biological questions and drug or biomarker discovery. Recently, chemical labeling strategies have been combined with mass spectrometry methods to generate thermodynamic information about protein folding and ligand binding interactions. The work in this thesis is focused on the development and application of two such chemical labeling protocols coupled with mass spectrometry including one termed, SUPREX (stability of unpurified proteins from rates of H/D exchange), and one termed SPROX (stability of proteins from rates of oxidation). The work described in this thesis is divided into two parts. The first part involves the application of SUPREX to the thermodynamic analysis of a protein folding chaperone, Hsp33, and its interaction with unfolded protein substrates. The second part involves the development of a new chemical labeling protocol that can be used to make protein folding and ligand binding measurements on the proteomic scale. </p><p>In the first part of this work, the SUPREX technique was used to study the binding interaction between the molecular chaperone Hsp33 and four different unfolded protein substrates including citrate synthase, lactate dehydrogenase, malate dehydrogenase, and aldolase. The results of the studies, which were performed at the intact protein level, suggest that the cooperativity of the Hsp33 folding/unfolding reaction increases upon binding with denatured protein substrates. This is consistent with the burial of significant hydrophobic surface area in Hsp33 when it interacts with its substrate proteins. The SUPREX derived Kd-values for Hsp33 complexes with four different substrates were also found to be all within a range of 3-300 nM. The interaction between Hsp33 and one of its substrates, citrate synthase (CS), was characterized at a higher structural resolution by using the SUPREX technique in combination with a protease digestion protocol. Using this protocol, the thermodynamic properties for both Hsp33 and CS were evaluated at different stages of binding, including reduced Hsp33 (inactive form), oxidized Hsp33 (active form), followed by native CS and finally of Hsp33ox -CS complexes before and after reduction with DTT. The results suggest that Hsp33 binds unfolded proteins that still have a significant amount of residual higher- order structure. Structural rearrangements of the substrate protein appear to occur upon reduction of the Hsp33-substrate complexes, which may facilitate the transfer of the substrate protein to other protein folding chaperone systems. </p><p>In the second part of this dissertation, a mass spectrometry-based covalent labeling protocol, which relies on the amidination rate of globally protected protein amine groups, was designed and applied to the thermodynamic analysis of several eight protein samples including: six purified proteins (ubiquitin, BCAII, RNaseA, 4OT, and lysozyme with, and without GlcNAc), a five-protein mixture comprised of ubiquitin, BCAII, RNaseA, Cytochome C, and lysozyme, and a yeast cell lysate. The results demonstrate that in ideal cases the folding free energies of proteins and the dissociation constants of protein-ligand complexes can be accurately evaluated using the protocol. Also demonstrated is the new method's compatibility with three different mass spectrometry-based readouts including an intact protein readout using MALDI, a gel-based proteomics readout using MALDI, and an LC-MS-based proteomics readout using isobaric mass tags. The results of the cell lysate sample analysis highlight the complementarity of the labeling protocol to other chemical modification strategies that have been recently developed to make thermodynamic measurements of protein folding and stability on the proteomic scale.</p> / Dissertation

Novel highly functionalized hybrid organic-inorganic materials were synthesized by polycondensation of bis[3-(trimethoxysilyl)propyl]amine in presence of cationic and anionic surfactants. Reaction media strongly affected gelation time. Thus, in basic media gelation occurred immediately while acid increased gelation time. Material structures were studied by IR spectroscopy, porosimetry, XRD, and SAXS methods. In spite of the absence of an inorganic linker, obtained bridged silsesquioxanes had mesoporous structure. A material prepared in the presence of dodecylamine as a template had higher surface area and narrow pore size distribution while the use of sodium dodecylbenzene sulfate resulted in formation of mesopores with wide size ranges. Accessibility of surface amine groups in silsesquioxanes was studied for molecules of acidic nature and different sizes: HCl, CO2 and picric acid. High contents of accessible amine groups in these materials make them prospective adsorbents for post-combustion CO2 capture.

Amine groups physiologically play an important role in regulating the growth behavior of cells and they have technological advantages for the conjugation of biomolecules. In this work, we present a method to deposit a copolymerized coating of dopamine and hexamethylendiamine (HD) (PDAM/HD) rich in amine groups onto a target substrate. This method only consists of a simple dip-coating step of the substrate in an aqueous solution consisting of dopamine and HD. Using the technique of PDAM/HD coating, a high density of amine groups of about 30 nmol cm⁻² was obtained on the target substrate surface. The PDAM/HD coating showed a high cross-linking degree that is robust enough to resist hydrolysis and swelling. As a vascular stent coating, the PDAM/HD presented good adhesion strength to the substrate and resistance to the deformation behavior of compression and expansion of a stent. Meanwhile, the PDAM/HD coating exhibited good biocompatibility and attenuated the tissue response compared with 316L stainless steel (SS). The primary amine groups of the PDAM/HD coating could be used to effectively immobilize biomolecules containing carboxylic groups such as heparin. These data suggested the promising potential of this PDAM/HD coating for application in the surface modification of biomedical devices.