Nanomateriais, incluindo as nanopartículas e nanotubos, tem sido extensivamente utilizados em diversas aplicações tecnológicas, devido principalmente às suas interessantes propriedades, advindas da alta relação área/volume. Para a efetiva aplicação destes materiais em dispositivos nanotecnológicos, no entanto, é crucial o desenvolvimento de sistemas altamente estáveis, que mantenham suas propriedades por longos períodos. Neste trabalho foi proposta uma rota sintética para a preparação de nanopartículas de ouro na presença de polieletrólitos e tióis numa só fase, juntamente com um estudo sistemático da estabilidade dos sistemas produzidos. Os espectros de UV-vis obtidos demonstraram a formação de nanopartículas de ouro, com banda plasmônica característica. As nanopartículas foram também visualizadas por imagens de microscopia de Transmissão. Análise de espectroscopia na região do infravermelho (FTIR) mostraram as ligações químicas que ocorrem entre os materiais constituintes dos sistemas híbridos de AuNPs. O estudo de estabilidade das AuNps foi realizado com medidas de espalhamento de luz dinâmico (DLS) bem como por medidas de UV-vis, o que permitiu a obtenção do tipo de solução e condições mais estáveis. Através de análise estatística, por meio da análise de componentes principais (PCA), foi possível verificar quais fatores influenciam de forma significativa a estabilidade das diferentes soluções preparadas. / The use of nanomaterials - including nanoparticles and nanotubes - for technological applications has received tremendous attention in the last few years, mainly due to their unique, size-dependent properties. The proper application of such nanomaterials in technological devices, however, has been limited by parameters such as their physical or chemical stability. In this Master´s dissertation, we introduce a single step synthetic route for preparation of gold nanoparticles in the presence of polyelectrolytes and thiols, with emphasis on the stability of the nanomaterials under different storage conditions. Four different hybrid nanoparticles had been investigated, containing either PAH or PVA as the polymeric phase, in the presence of 3-AMP or 11-AMP thiols, respectively. After synthesis, the formation of the Au nanoparticles (AuNPs) was evidenced by UV-vis spectroscopy, upon appearance of a characteristic plasmonic band centered at ca. 510 or 540 nm, depending on the stabilizing agents used. The AuNPs were also investigated via TEM images. FTIR analyses evidenced that electrostatic interactions occurred between the thiols and the polyelectrolytes, within the hybrid nanoparticles structure. The stability of the four different systems was detailed investigated using UV-Vis spectroscopy, dynamic light scattering (DLS), and visual analyses. The data pointed to the higher stability presented by the AuNps stabilized with PAH in the presence of 3-AMP (PAH/3-AMP AuNPs). In contrast, the AuNPs stabilized with PVA exhibited the lowest stability. This feature was corroborated by statistical analysis, using principal component analysis (PCA), through which was possible to identify the main factor affecting AuNPs stability.

In this article, we examined different synthetic approaches with varying adding starting materials for the thiol containg schiff-base complex [ZnL1]2(L1=o-C6H4(SH)(CH=NC6H4SH-o)). We found that the key step for successful synthesis of [ZnL1]2 is the formation of zinc aldehyde intermediate. We also break the [ZnL2]2 dimer by adding chelating agent, TMEDA, to obtain the Zn(L1)(TMEDA) monomer. It¡¦s single crystal X-ray structure confirmed, the structure of the target ligand L1. We also synthesized [NiL1]2 by transmetalation of [ZnL1]2 - an easier synthetic approach. We further reduced the imine part on L1 of [ZnL1]2 and Zn(L1)(TMEDA) to get [ZnL2]2(L2=o-C6H4(SH)(CH2NHC6H4SH-o)) and Zn(L2)(TMEDA) respectively for future reactivity studies.

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The cell membrane is a complex structure with many functions that can affect cellular processes. For this reason, a model possessing characteristics similar to those of the natural cell membrane is required for the investigation of various functions and properties belonging to this important structure. Presented is the synthesis of a glycolipid analogue possessing both a C-4’ thiol functionalization (for binding to an Au(111) electrode) and an anomeric triazole-linked phytanyl chain (for integration into a phospholipid bilayer). Additionally, a similar analogue without thiol functionalization was synthesized for use as a dilution molecule to prevent aggregation of the tether analogue during monolayer assembly. Aqueous compartments will exist above and below the bilayer allowing for future integration and functional analysis of membrane proteins. Glycosylation at the anomeric position of a lactosyl donor with propargyl alcohol gave a propargyl lactoside that underwent several steps of selective protection to give access at O-4’ for triflation. Displacement of the triflate gave a thioacetate functionalized disaccharide. Both the propargyl lactoside and the thioacetate functionalized disaccharide underwent copper-catalyzed azide-alkyne cycloadditions with phytanyl azide. Subsequent deprotections gave two novel glycolipid analogues. / NSERC

Current methods of identifying semen include preliminary methods such as an alternate light source (ALS) and color tests which test for the presence of acid phosphatase (AP). Confirmatory methods for identifying semen include the microscopic identification of spermatozoa which typically use staining methods such as the Christmas Tree Stain (KPIC) or hematoxylin and eosin stain (H&E). Other methods include immunoassay cards that test for the components of semen such as prostate specific antigen (PSA) and semenogelin (Sg). One common fluorescent staining method used to identify the presence of spermatozoa is SPERM HY-LITERTM which uses an anti-human sperm-specific mouse monoclonal antibody coupled to an AlexaFluor 488 dye. This causes the entire head of the sperm cell to fluoresce when a FITC filter is used. It also utilizes a 4,6-diamidino-2- phenylindole (DAPI) fluorescent dye that stains all cell nuclei non-specifically. This allows the analyst to easily identify whether sperm is present in the sample. A drawback of the antibody labeling procedure is that there are many washing and transfer steps that can lead to sample loss; thus a need for a new, optimized staining method exists. During spermiogenesis, protamines replace histones to further condense the DNA of the sperm nucleus. Humans express two proamines, protamine 1 (P1) and protamine 2 (P2). The protamines contain an arginine-rich core as well as cysteine residues. The high levels of arginine create a net positive charge that allows for stronger binding to DNA. The cysteine residues allow for the formation of inter and intra-protamine disulfide bonds which allow for the chromatin compaction. If the disulfide bonds found in protamines can be reduced to produce free thiols, a thiol-reactive probe can bind and label the protamines in the sperm nucleus. Reduction of the disulfide bonds can be performed by use of reagents such as dithiothreitol (DTT) or tris-(2-carboxyethyl)phosphine (TCEP). From the literature on thiol-reactive probes, it is suggested that TCEP be used as a reducing agent due to its structure. DTT contains thiol groups and when removed from the sample, thiol groups may be oxidized back into disulfide bond. In addition, TCEP is more stable than DTT at a higher pH and higher temperatures. Once disulfide bonds have been reduced, a thiol-reactive probe may be introduced. There are many different types of probes that may be used. Maleimides are commonly used for thiol modification and quantitation. When the compound encounters a thiol group, the thiol group is added across the double bond, yielding a thioether. The reagent used is N-7-dimethylamino-4-methylcoumarin-3-yl)maleimide (DACM). It absorbs light at 376 nm and emits light at 476 nm, producing a blue fluorescence. The dye is nonfluorescent until it reacts with a thiol group. In this research, both sperm and epithelial cells were added to the slides in order to develop a novel staining procedure. The initial protocol used TCEP to break the disulfide bonds followed by DACM to bind free thiol groups. Sodium dodecyl sulfate (SDS) was then added to the protocol to lyse cells. DTT was tested for use as a reducing agent as well. The purpose of establishing this protocol was to design a procedure for rapid labeling of sperm that does not require antibody labeling. In the antibody labeling procedure, there are many washing and transfer steps. The proposed method may limit the number of procedural steps resulting in less loss of biological material. It can also help to limit the time-consuming methods of the current staining techniques, such as KPIC and H&E.

Nanomateriais, incluindo as nanopartículas e nanotubos, tem sido extensivamente utilizados em diversas aplicações tecnológicas, devido principalmente às suas interessantes propriedades, advindas da alta relação área/volume. Para a efetiva aplicação destes materiais em dispositivos nanotecnológicos, no entanto, é crucial o desenvolvimento de sistemas altamente estáveis, que mantenham suas propriedades por longos períodos. Neste trabalho foi proposta uma rota sintética para a preparação de nanopartículas de ouro na presença de polieletrólitos e tióis numa só fase, juntamente com um estudo sistemático da estabilidade dos sistemas produzidos. Os espectros de UV-vis obtidos demonstraram a formação de nanopartículas de ouro, com banda plasmônica característica. As nanopartículas foram também visualizadas por imagens de microscopia de Transmissão. Análise de espectroscopia na região do infravermelho (FTIR) mostraram as ligações químicas que ocorrem entre os materiais constituintes dos sistemas híbridos de AuNPs. O estudo de estabilidade das AuNps foi realizado com medidas de espalhamento de luz dinâmico (DLS) bem como por medidas de UV-vis, o que permitiu a obtenção do tipo de solução e condições mais estáveis. Através de análise estatística, por meio da análise de componentes principais (PCA), foi possível verificar quais fatores influenciam de forma significativa a estabilidade das diferentes soluções preparadas. / The use of nanomaterials - including nanoparticles and nanotubes - for technological applications has received tremendous attention in the last few years, mainly due to their unique, size-dependent properties. The proper application of such nanomaterials in technological devices, however, has been limited by parameters such as their physical or chemical stability. In this Master´s dissertation, we introduce a single step synthetic route for preparation of gold nanoparticles in the presence of polyelectrolytes and thiols, with emphasis on the stability of the nanomaterials under different storage conditions. Four different hybrid nanoparticles had been investigated, containing either PAH or PVA as the polymeric phase, in the presence of 3-AMP or 11-AMP thiols, respectively. After synthesis, the formation of the Au nanoparticles (AuNPs) was evidenced by UV-vis spectroscopy, upon appearance of a characteristic plasmonic band centered at ca. 510 or 540 nm, depending on the stabilizing agents used. The AuNPs were also investigated via TEM images. FTIR analyses evidenced that electrostatic interactions occurred between the thiols and the polyelectrolytes, within the hybrid nanoparticles structure. The stability of the four different systems was detailed investigated using UV-Vis spectroscopy, dynamic light scattering (DLS), and visual analyses. The data pointed to the higher stability presented by the AuNps stabilized with PAH in the presence of 3-AMP (PAH/3-AMP AuNPs). In contrast, the AuNPs stabilized with PVA exhibited the lowest stability. This feature was corroborated by statistical analysis, using principal component analysis (PCA), through which was possible to identify the main factor affecting AuNPs stability.

Hydrogels are hydrophilic, three-dimensional polymeric networks prepared through chemical or physical conjugation. Hydrogels are recognized for their tunable properties, specifically through changes in the backbone of the polymers, such as 1) modifying the number of hydrophobic chain lengths, 2) adding or removing cleavable linkages, 3) varying reactive-end groups, 4) increasing or decreasing the weight percent of the hydrogel, and 5) combining two or more hydrogel networks into one, namely creating an interpenetrating network. We synthesized and characterized on- and off-demand, dissolvable hydrogels for use as burn wound dressings, polypectomy bandages, and vascular occlusion devices, and within interpenetrating networks. The hydrogels are composed of PEG-based crosslinkers, and PEI-based hyperbranched macromers which were prepared in high yields. In context of burn wound dressings, there is an unmet need for an adherent dressing with ease of removal, such as a dissolvable hydrogel dressing. In a model of in vivo porcine burn wounds, our hydrogel shows superior burn healing relative to traditional dressings such as sterile gauze pad and non-adherent foam dressings. When our hydrogel was removed, no newly formed tissue adhered to the dressing, and immunohistochemical stains exhibit improved inflammation and necrosis. When our hydrogel was used as an in vivo polypectomy sealant, we observed ease of application and adhesion to the colon, despite peristalsis. In in vitro studies, we observe no migration of bacteria through the hydrogel. As a vascular occlusion device, our hydrogels withstand an ex vivo burst pressure of up to 440mmHg on average, over 3x that of arterial pressure. Furthermore, we prepared an interpenetrating network from two hydrogel formulations both using SN2 chemistry with tunable mechanical properties. The hydrogel formulations highlighted in this work vary in gelation, mechanical properties, swelling, dissolution, and adhesion based on the structure of the polymer and reactive groups. These hydrogels represent a future direction in wound dressings and sealants as they prevent bacterial migration into an open wound, adhere to tissue, provide a moist wound environment, demonstrate structure-function relations allowing for tunable mechanical properties, and are biocompatible. / 2022-03-10T00:00:00Z

Deux types de revêtements constitués d'environ 80% d'huile végétale ont été élaborés par chimie thiol-X sous UV. Le premier a été obtenu sous UV à partir d'huiles de lin native et standolisées en présence de 0,5 équivalent (SH/ène) de divers thiols, sous air, sans photoamorceur ni solvant. L'effet bénéfique de l'oxydation des acides gras sur la réaction d'addition thiol-ène et les propriétés finales des revêtements a été démontré. Ces matériaux présentent des propriétés équivalentes à celles des films obtenus par oxydation de l'huile de lin, faisant de ce procédé une alternative intéressante à la siccativation des huiles. Le deuxième type de revêtement a été obtenu sous UV à partir d'une huile de coton époxydée en présence de 0,25 équivalent (SHlépoxy) de 7- mercapto-4-méthyl coumarine et d'un photogénérateur de base permettant d'amorcer, sous air, la réaction d'addition thiol-époxy et l'homopolymérisation des fonctions époxy. Ces revêtements sont autoréparables sous UV. / Two types of coatings constituted about 80 wt% of vegetable oil were prepared by photoinitiated thiol-X chemistry. The first one has been prepared by crosslinking of native and stand linseed oil triglycerides in the presence of 0.5 equivalent of various thiols (SH/ene) under air and UV radiation, without photoinitiator or solvent. The oxidation of fatty acids has shown a beneficial effect on the thiol-ene addition as well as on the final properties of coatings. This process is thus an interesting alternative for the drying of oils. The second type of coating has been obtained by photocrosslinking triglycerides of epoxidized cottonseed oil in the presence of 0.25 equivalent (SH/epoxy) of 7-mercapto-4-methyl coumarine and a photobase generator under air. This latter initiated both thiol-epoxy addition and homopolymerization of epoxy functions. This coating could be auto-healable under UV exposure.

Thiols are one of the most important classes of chemicals used broadly in organic synthesis, biological chemistry, and nanosciences. Thiol pKa values are key indicators of thiol reactivity and functionality. This study is an internally-referenced Raman-based pH titration method that enables reliable quantification of thiol pKa values for both mono- and di-thiols in water. The degree of thiol ionization is monitored directly using the peak intensity of the S-H stretching feature relative to an internal reference peak as a function of solution pH. The thiol pKa values and Raman activity relative to its internal reference were then determined by curveitting the experimental data with equations derived on the basis of the Henderson-Hasselbalch equation. Using this Raman titration method, first and second thiol pKa values for 1,2-benzenedithol in water were determined for the first time. This method is convenient to implement and its underlying theory is easy to follow.

The foundation for supramolecular chemistry is in nature; by studying these archetypes, chemists have devised methods of recreating these complex interactions in the laboratory. Of particular interest is the interplay between enzyme- more specifically, its active site- and the target substrate. Utilizing recent advancements in self-assembled monolayers, progress towards a more-accurate flavoenzyme model has been demonstrated.