Conselho Nacional de Desenvolvimento Científico e Tecnológico / This work presents the synthesis of compounds and their triazenes complexes of gold(I), silver(I), platinum(II) and paladium(II). Triazenes have three nitrogen atoms connected in sequence [ N=N N(H) ] and, when deprotonated, they become excellent ligands in coordination chemistry. The synthesized ligands have ortho nitro substituent and variable substituent halogenated, or also in a position. Characterizations were performed using various techniques: thermogravimetric analysis, ultraviolet and visible spectroscopy, infrared and proton nuclear magnetic resonance, and the main focus of this work was the structural characterization of the complexes by X-ray diffraction on monocrystal, with emphasis the study of these supramolecular arrangements. Nitro and halide substituents (F, Cl, Br and I) providing the formation of various types of interactions, which form supramolecular arrangement. Four ligands were synthesized 1-(2-flurorphenyl)-3-(2-nitrophenyl)triazene (A), 1-(2-chlorophenyl)-3-(2-nitrophenyl)triazene (B), 1-(2-bromophenyl)-3-(2-nitrophenyl)triazene (C), 1-(2-iodophenyl)-3-(2-nitrophenyl)triazene (D) and thirteen complexes {[1-(2-fluorophenyl)-3-(2-nitrophenyl)triazenide](triphenilphosfine)gold(I)} (1), {[1-(2-chlorophenyl)-3-(2-nitrophenyl)triazenide](triphenilphosfine)gold(I)} (2), {[1-(2-bromophenyl)-3-(2-nitrophenyl)triazenide](triphenilphosfine)gold(I)} (3), {trans- bis-[1-(2-chlorophenyl)-3-(2-nitrophenyl)triazenide]-bis-(pyridine)paladium(II)} (4), {trans- bis-[1-(2-bromophenyl)-3-(2-nitrophenyl)triazenide]-bis-(pyridine)paladium(II)} (5), {trans- bis-[1-(2-iodophenyl)-3-(2-nitrophenyl)triazenide]-bis-(pyridine)paladium(II)} (6), {cis- bis-[1-(2-chlorophenyl)-3-(2-nitrophenyl)triazenide]-bis-(pyridine)platinum(II)} (7), {cis- bis-[1-(2-bromophenyl)-3-(2-nitrophenyl)triazenide]-bis-(pyridine)platinum(II)} (8), {cis- bis-[1-(2-iodophenyl)-3-(2-nitrophenyl)triazenide]-bis-(pyridine)platinum(II)} (9), {trans-[1-(2-bromophenyl)-3-(2-nitrophenyl)triazenide]-bis-(pyridine)(chloro)platinum(II)} (10), {cis- [1-(2-bromophenyl)-3-(2-nitrophenyl)triazenide]-ditriphenylphosfine(chloro)platinum(II)} (11), {bis-[1-(2-iodophenyl)-3-(2-nitrophenyl)triazenide]silver(I)} (12) e {[1-(2-fluorophenyl)-3-(2-nitrophenyl)triazenide](triphenylphosfine)silver(I)} (13). For the purpose of Bioinorganic studying the triazenido complexes of gold (I), and Platinum (II) were subjected to evaluation of biological activity shown promising results. / Este trabalho apresenta a síntese de compostos triazenos e seus complexos de ouro(I), prata(I), platina(II) e paládio(II). Os compostos triazenos possuem três átomos de nitrogênio ligados em sequência [ N=N N(H) ]. Quando desprotonados transformam-se em excelentes ligantes com grande exploração na química de coordenação. Os pré-ligantes sintetizados possuem substituinte nitro em posição orto e variável substituinte halogenado, também em posição orto. Foram realizadas caracterizações com diversas técnicas: análise termogravimétrica (TGA), espectroscopia ultravioleta e visível, infravermelho e ressonância magnética nuclear de próton, sendo que o foco principal deste trabalho foi a caracterização estrutural dos complexos por difração de raios-X em monocristal, com destaque no estudo supramolecular destes compostos. Os substituintes nitro e haletos (F, Cl, Br e I) proporcionam a formação de diversos tipos de interações, as quais constituem arranjo supramoleculares. Foram sintetizados quatro pré-ligante 1-(2-fluorfenil)-3-(2-nitrofenil)triazeno (A), 1-(2-clorofenil)-3-(2-nitrofenil)triazeno (B), 1-(2-bromofenil)-3-(2-nitrofenil)triazeno (C), 1-(2-iodofenil)-3-(2-nitrofenil)triazeno (D) e treze complexos {[1-(2-fluorofenil)-3-(2-nitrofenil)triazenido](trifenilfosfina)ouro(I)} (1), {[1-(2-clorofenil)-3-(2-nitrofenil)triazenido](trifenilfosfina)ouro(I)} (2), {[1-(2-bromofenil)-3-(2-nitrofenil)triazenido](trifenilfosfina)ouro(I)} (3), {trans- bis-[1-(2-clorofenil)-3-(2-nitrofenil)triazenido]-bis-(piridina)paládio(II)} (4), {trans- bis-[1-(2-bromofenil)-3-(2-nitrofenil)triazenido]-bis-(piridina)paládio(II)} (5), {trans- bis-[1-(2-iodofenil)-3-(2-nitrofenil)triazenido]-bis-(piridina)paládio(II)} (6), {cis- bis-[1-(2-clorofenil)-3-(2-nitrofenil)triazenido]-bis-(piridina)platina(II)} (7), {cis- bis-[1-(2-bromofenil)-3-(2-nitrofenil)triazenido]-bis-(piridina)platina(II)} (8), {cis- bis-[1-(2-iodofenil)-3-(2-nitrofenil)triazenido]-bis-(piridina)platina(II)} (9), {trans-[1-(2-bromofenil)-3-(2-nitrofenil)triazenido]-bis-(piridina)(cloro)platina(II)} (10), {cis- [1-(2-bromofenil)-3-(2-nitrofenil)triazenido]-ditrifenilfosfina(cloro)platina(II)} (11), {bis-[1-(2-iodofenil)-3-(2-nitrofenil)triazenido]prata(I)} (12) e {[1-(2-fluorofenil)-3-(2-nitrofenil)triazenido](trifenilfosfina)prata(I)} (13). Para fins de estudar a Bioinorgânica dos complexos triazenidos de Ouro(I) e Platina(II), os compostos foram submetidos a avaliação de atividade biológica apresentando resultados promissores.

Orientadores: Pedro Paulo Corbi, André Luiz Barboza Formiga / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-24T12:00:41Z (GMT). No. of bitstreams: 1 Abbehausen_Camilla_D.pdf: 19393479 bytes, checksum: 3e6aaec4c411ad2e24a5f26226d19220 (MD5) Previous issue date: 2014 / Resumo: Complexos metálicos inéditos de paládio, platina, ouro e prata com diferentes classes de ligantes foram desenvolvidos. Dentre os ligantes selecionados estão a L-aliina (ali) e a N-acetil-L-cisteína (nac) que compreendem a classe dos aminoácidos, a 2-mercaptotiazolina (mtz), dentro da classe das tiazolidinas, a sulfadoxina (sfx), representante da classe das sulfonamidas, e ligantes N-heterociclos, piridino derivados com diferentes valores de pKa. Complexos de Pd(II) com L-aliina ([Pd(C6H11NO3S)2]), Ag(I) com N-acetil-L-cisteína ([Ag(C5H9NO3S)]), Ag(I) com sulfadoxina ([Ag(C12H13N4O4S)]), Au(I) com 2-mercaptotiazolina ([Au(CN)(C3H5NS2)]) e uma série de complexos trifenilfosfinoouro(I) com ligantes N-heterociclos ([Au(PPh3)L]+) foram sintetizados e caracterizados por um conjunto de análises químicas e espectroscópicas. Estudos in vitro das sua atividades antibacterianas e antitumorais foram também reali-zados. Atividades antibacterianas e antitumorais significativas foram encontradas para o complexo de Pd(II) com ali e o DNA se mostrou um alvo provável. O complexo Au(I) com mtz apresentou atividade antitumoral e antibacteriana bastante expressiva e uma investigação preliminar de seus mecanismos de ação também demonstrou que o DNA não parece ser o alvo destes compostos nas células. Os complexos de Ag(I) com nac e sfx apresentaram atividades antibacterianas significativas sobre cepas Gram-positivas e Gram-negativas. Os ligantes N-heterociclos 4-picolina (pic), 2-amino-4-picolina (NH2pic) e dimetilaminopriridina (DMAP) possuem valores de pKa crescentes, e foram selecionados para investigar o efeito do pKa na atividade biológica de complexos trife-nilfosfinoouro(I) do tipo [Au(PPh3)L]+, onde L = N-heterocíclico. Esta investigação foi realizada por avaliações in vitro de suas atividades antitumorais, além de estudos do acúmulo celular, do bloqueio do ciclo celular e por interações com biomoléculas como o DNA e proteínas dedos de zinco (zinc fingers, ZF). A atividade antitumoral foi expressiva e os estudos de suas interações com os ZF mostraram que a inibição pode ser modulada com a variação do tipo de proteína e do ligante N-heterociclo selecionado / Abstract: Novel palladium, platinum, gold and silver complexes with different classes of ligands were designed. The selected ligands were L-alliin (ali) and N-acetyl-L-cysteine (nac) which are aminoacids, 2-mercaptothiazoline (mtz), which belongs to the class of thiazolidines, sulfadoxine that represents the class of sulfonamides and N-heterocyclic pyridine derivatives, with different values of pKa. Complexes of Pd(II) with L-alliin ([Pd(C6H11NO3S)2]), Ag(I) with N-acetyl-L-cysteine ([Ag(C5H9NO3S)]), Ag(I) with sulfa-doxine ([Ag(C12H13N4O4S)]), Au(I) with 2-mercaptotiazoline [(Au(CN)(C3H5NS2)]) and a series of complexes of triphenylphosphinegold(I) with N-heterocyclic ligands ([Au(PPh3)L]+) were synthesized and characterized by a set of chemical and spectroscopic analyses. Antibacterial and antitumor activities in vitro were also studied. Significant antibacterial and antitumor activities were found for Pd(II) with ali, and the DNA is the probable biological target. The Au(I) with mtz complex presented noteworthy antitumor and antibacterial activities, and preliminary investigations of its biological mechanism showed that, the DNA is probable not a target of this complex in the cells. The silver complexes with nac and sfx presented significant antibacterial activities. The series of N-heterocyclic ligands 4-picoline (pic), 2-amino-4-picoline (NH2pic) and dimethylaminopyridine (DMAP) shows crescent pKa values and they were selected to investigate the pKa effect in the biological activity of the complexes triphenylphosphinegold(I) [Au(PPh3)L]+, which L = N-heterocyclic. This investigation was performed by evaluation of its antitumor activities in vitro, and also by studies of cell uptake, cell cycle arrest and by interactions with biomolecules as DNA and zinc finger proteins (ZF). The antitumor activity was expressive and the studies with ZF showed that the inhibition is dependent of the kind of protein and of the N-heterocyclic ligand / Doutorado / Quimica Inorganica / Doutora em Ciências

The transfer of a hydrogen atom is a crucial step in a wide variety of chemical and biological processes and modus operandi of many metalloenzymes. While several factors that govern the reactivity and selectivity were already clarified in the past century, a growing body of experimental and theoretical studies also revealed numerous gaps in our unified understanding. As a consequence, the direct functionalization of non-activated C-H bonds by synthetic catalysts is still very limited. In the thesis, the hydrogen-atom-abstraction (HAA) reactions are broken down into the elementary proton- and electron-transfer steps and the reactivity/selectivity of oxidants is analyzed with respect to their physico-chemical properties, acidity constants and reduction potentials. First, a quantum chemical (QM)-based computational protocol for calculation of reduction potentials of iron complexes is introduced and validated over a large series of experimental data, including a set of challenging mononuclear FeIV O species that provide direct connection to biomimetic non-heme iron catalysis. Next, the methodology is extended to deal with reduction potentials of transition-metal complexes possessing higher total molecular charges, experimentally measured in polar solvents. In such cases, the accurate description of solvation...

Quercetin-Dioxygenasen (QueD) katalysieren die oxidative Spaltung von Quercetin, einem Pflanzenfarbstoff aus der Gruppe der Flavonole und bilden dabei das entsprechende Depsid und Kohlenstoffmonoxid. Interessanterweise werden in den QueDs natürlicher Quellen verschiedene zweiwertige Metallionen als Cofaktor im aktiven Zentrum des Enzyms gefunden. So stellt sich die Frage, welche Rolle dem Metallzentrum im Mechanismus der Katalyse zukommt. Um die Umgebung des Metallions im aktiven Zentrum mit einer biomimetischen, niedermolekularen Modellverbindung nachzuempfinden, wurde das Trispyrazolylborato-Ligandsystem (Tp) gewählt und als Substratanalogon diente 3-Hydroxyflavon (FlaH). So konnte ein strukturelles und funktionelles Modellsystem der NiQueD in Form von des Tp*NiFla-Komplexes synthetisiert und vollständig charakterisiert werden. Es erfolgte eine Variation dieses Systems, um verschiedene Einflüsse auf die Reaktivität mit Disauerstoff zu untersuchen. Der Austausch der Carbonylfunktion von FlaH durch C=S sowie C=Se Einheiten führte bei der Umsetzung mit O2 nicht zu der antizipierten Erhöhung der Reaktionsraten, stattdessen wurden zusätzlich Nebenreaktionen beobachtet. Die Veränderung der Substituenten am Tp-Ligandrückgrat zeigte, dass sterisch anspruchsvollere Gruppen zur Erhöhung der Reaktionsraten bei Umsetzungen mit O2 führen, vermutlich weil das Substrat für eine direkte Reaktion mit O2 leichter zugänglich wird. Durch systematische Variation der 3d-Übergangsmetallionen im Zentrum der Modellkomplexe wurde ein Einfluss auf die Redoxeigenschaften des metallgebundenen Flavonolats beobachtet. Die reversiblen Redoxpotentiale stehen in direktem Zusammenhang mit der Reaktionsrate. Ergebnisse mechanistischer Untersuchungen legen einen outer-sphere Elektronentransferprozess nahe, bei dem ein Elektron des Flavonolats direkt auf O2 übertragen wird. Durch Rekombination der entstandenen Radikale werden die nach biomimetischer Reaktion zu erwartenden Produkte gebildet. / Quercetin dioxygenases (QueD) catalyze the oxidative cleavage of quercetin, a flavonol commonly found in fruits and leaves, forming the corresponding depside and carbon monoxide. Interestingly, quercetinases of various natural sources show a different selectivity towards the divalent metal ion incorporated as cofactor, raising the questions on the role of the metal center in the mechanism of catalysis. Synthetic can help to gain insight into the mechanistic pathway of the reaction and thus clearify such questions. In order to synthesize a biomimetic model compound, the trispyrazolylborato ligands (Tp) were used and 3 hydroxyflavone (FlaH) was chosen as substrate. The compound Tp*NiFla with a was synthesized and fully characterized as a structural and functional model for the NiQueD. Based on this, the system was varied in different ways in order to investigate the influence on the reactivity towards O2. It was shown that the substitution of the carbonyl function of FlaH by C=S and C=Se units did not lead to an increase in the reaction rates, but additionally to undesirable side reactions. By altering the residues on the Tp ligand backbone it turned out that sterically more demanding groups increase the rates of reaction with dioxygen, likely because the substrate is more accessible for direct reaction with O2. By systematic variation of the metal ions in the center of the model compounds, an influence on the redox properties of the metal-bound flavonolate was observed. For the first time, reversible redox reactions of flavonolate bound to 3d transition metals was demonstrated. Furthermore, a direct relation of the redox potentials to the reaction rates emerged. The results of mechanistic studies indicate that all model complexes react via an initial outer-sphere electron transfer process, in which an electron of the flavonolate is directly transferred to O2. By recombination of the formed radicals, the products expected for a biomimetic process can be obtained.

ピリジン配位子を持つメチル化シクロデキストリン二量体と水溶性鉄ポルフィリンから構成される超分子ヘムタンパク質モデル化合物"hemoCD"を用いて、過酸化水素などのヒドロペルオキシドとの反応から、ペルオキシダーゼなどの酸化酵素における反応中間体および酸化活性種の捕捉とそれら反応性について検討を行った。 / 博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University

No description available.

Notre travail de thèse a été dédié à la synthèse et à la caractérisation bio-physicochimique de complexes osmium nitrosyle, qui pourraient relarguer l’oxyde nitrique (NO) au sein des cellules tumorales pour conjuguer les propriétés anticancéreuses souvent associés aux complexes du groupe du platine avec la toxicité de l’oxyde nitrique. Le premier chapitre de notre mémoire de thèse présente l’état de l’art dans le domaine des composés anticancéreux et le rôle de l’oxyde nitrique dans l’apoptose cellulaire. Le deuxième chapitre concerne la synthèse et la caractérisation de complexes d’azole (C)[Os(NO)Cl4(A)] (C = Bu4N+, Na+, HA+; A = indazole, pyrazole, benzimidazole, imidazole), où le plus cytotoxique est H2ind[cis-Os(NO)Cl4(indazole)]. Le troisième chapitre est consacré à l’étude cinétique et thermodynamique par RMN de l’isomérisation trans ↔ cis du complexe (Bu4N)[Os(NO)Cl4(indazole)] qui met en évidence un processus d’isomérisation de type dissociatif. Le quatrième chapitre concerne la synthèse et la caractérisation de complexes d’aminoacides (Bu4N)[Os(NO)Cl4(L)] (L = gly, picolinate, L-, D-pro) qui ont une très faible activité antiproliférative. Le dernier chapitre est consacré à la synthèse et à la caractérisation de clusters hétérométalliques [{Os(NO)Cl3(Ox)}4Ln] (Ln = Gd, Tb, Dy, Y ; Ox=oxalate) dans lesquels la coordinance 8 ou 9 du lanthanide dépend de son rayon ionique. Le précurseur {Os(NO)Cl3(Ox)} a l’activité antiproliférative la plus élevée de tous les complexes osmium nitrosyle connus / The PhD thesis was dedicated to the synthesis and bio-physic-chemical characterization of osmium nitrosyl complexes which could release nitric oxide (NO) in tumor cells to combine the anticancer properties of the platinum group complexes and the nitric oxide cytotoxicity. The first chapter presents the state of the art in the field of anticancer compounds and the role of nitric oxide in the apoptosis. The second chapter concerns the synthesis and characterization of azole complexes with the general formulae (C)[Os(NO)Cl4(A)] (C = Bu4N+, Na+, HA+; A = indazole, pyrazole, benzimidazole, imidazole), where the most cytotoxic is H2ind[cis-Os(NO)Cl4(indazole)]. The third chapter focuses on the kinetic and thermodynamic study of the trans ↔ cis isomerisation of (Bu4N)[Os(NO)Cl4(indazole)] complex by NMR, which highlights a dissociative isomerisation process. The fourth chapter concerns the synthesis and the characterization of amino acids complexes with the general formulae (Bu4N)[Os(NO)Cl4(L)] (L = gly, picolinate, L-, D-pro) of whose antiproliferative activity is very low. The last chapter is dedicated to the synthesis and characterization of heterometallic clusters with the general formulae [{Os(NO)Cl3(Ox)}4Ln] (Ln = Gd, Tb, Dy, Y ; Ox = oxalate), where the coordination number 8 or 9 depends on its ionic radius. The precursor {Os(NO)Cl3(Ox)} has the highest antiproliferative activity among of all osmium nitrosyl known so far

A teragnóstica de doenças tem sido extremamente marcada nos últimos anos por nanomateriais formados pela conjugação de nanopartículas a biomoléculas, pois a aplicação de tecnologias baseadas em materiais na dimensão nanométrica é capaz de aumentar a seletividade, sensibilidade e praticidade dos métodos atualmente empregados, ou mesmo criar novos métodos de diagnóstico e tratamento de doenças. Dentre os vários tipos de nanomateriais desenvolvidos, aqueles baseados em nanopartículas de ouro ou nanopartículas magnéticas apresentam propriedades químicas e físicas diferenciadas que propiciam novas possibilidades. Por exemplo, a presente tese demonstrou que nanopartículas superparamagnéticas são excelentes agentes de contraste em exames de imagem por ressonância magnética (IRM) por serem mais seguros, apresentarem melhor contraste nas imagens e possibilitarem direcionar/concentrar o material em tecidos ou tumores através de um gradiente de campo magnético aplicado. Foram feitos numerosos ensaios de toxicidade tanto in vitro quanto in vivo para assegurar a segurança da aplicação de nanopartículas no organismo, cujo potencial de uso somente se tornará uma realidade caso os nanomateriais se mostrem não tóxicos e biocompatíveis. Apesar dos significativos avanços na área da aplicação desses nanomateriais, não foram encontrados na literatura modelos capazes de explicar ou prever por quais sítios de ligação devem ocorrer as interações proteína-nanopartícula, como também não foram encontrados estudos sistemáticos acerca dos fatores que determinam a estabilidade e a funcionalidade dos nanobioconjugados (NBCs). Assim, nesta tese buscamos compreender os fatores responsáveis pela ligação/adsorção das proteínas nas nanopartículas de ouro e sua influência sobre a estabilidade das suspensões e a funcionalidade das proteínas. Desta forma, foram obtidos NBCs com propriedades adequadas para o desenvolvimento ou aprimoramento de ensaios de diagnóstico e até para o tratamento de doenças. Foi demonstrado o potencial das nanopartículas de ouro para melhorar a performance de imunoensaios do tipo ELISA, mas também podem ser utilizadas para o desenvolvimento de métodos de diagnóstico, explorando as propriedades plasmônicas das nanopartículas de ouro acopladas a técnicas como SERS, SPR e microscopia Raman confocal. / Theranostics has been intensively pursued in recent years using hybrid materials based on nanoparticles conjugated with biomolecules. This is an interesting strategy to increase the selectivity and sensitivity, as well as to improve the currently used methods facilitating their use or creating new ones. Among the various types of nanomaterials, those based on gold and magnetic nanoparticles exhibit interesting chemical and physical properties in the biological environment, differing from that of free drugs or current explored in assay methods. For example, superparamagnetic nanoparticles are excellent contrast agents for magnetic resonance image (MRI) diagnostics because they are safer, present a better contrast efficiency for imaging and can be magnetically accumulated in tissues or tumors using a magnetic field. Numerous in vitro and in vivo toxicity assays were performed to ensure the safety for medical applications. Clearly, these type of applications only will be realized if nanomaterials prove to be nontoxic and biocompatible. This imply an strict control on their structure and composition. However, despite the significant advances in the development of such nanomaterials, there were not found in the literature model systems explaining or that can be used to predict by which sites the protein-nanoparticle binding should take place. In addition, no systematic studies on the factors determining the stability and the functionality of nanobioconjugates (NBC) were found. Thus, this thesis is focused in unveiling the factors responsible for binding/adsorption of proteins on gold nanoparticles and their influence on the colloidal stability of hybrid nanoparticles suspensions while keeping the functionality of biomolecules. In fact, NBC with enhanced properties suitable for the development of diagnostic methods and even for treatment of diseases were obtained. These nanomaterials can improve the ELISA immunoassay, or other diagnosis methods can be developed by using the gold nanoparticles plasmonic properties in association with SERS, SPR and confocal Raman microscopy techniques.

A teragnóstica de doenças tem sido extremamente marcada nos últimos anos por nanomateriais formados pela conjugação de nanopartículas a biomoléculas, pois a aplicação de tecnologias baseadas em materiais na dimensão nanométrica é capaz de aumentar a seletividade, sensibilidade e praticidade dos métodos atualmente empregados, ou mesmo criar novos métodos de diagnóstico e tratamento de doenças. Dentre os vários tipos de nanomateriais desenvolvidos, aqueles baseados em nanopartículas de ouro ou nanopartículas magnéticas apresentam propriedades químicas e físicas diferenciadas que propiciam novas possibilidades. Por exemplo, a presente tese demonstrou que nanopartículas superparamagnéticas são excelentes agentes de contraste em exames de imagem por ressonância magnética (IRM) por serem mais seguros, apresentarem melhor contraste nas imagens e possibilitarem direcionar/concentrar o material em tecidos ou tumores através de um gradiente de campo magnético aplicado. Foram feitos numerosos ensaios de toxicidade tanto in vitro quanto in vivo para assegurar a segurança da aplicação de nanopartículas no organismo, cujo potencial de uso somente se tornará uma realidade caso os nanomateriais se mostrem não tóxicos e biocompatíveis. Apesar dos significativos avanços na área da aplicação desses nanomateriais, não foram encontrados na literatura modelos capazes de explicar ou prever por quais sítios de ligação devem ocorrer as interações proteína-nanopartícula, como também não foram encontrados estudos sistemáticos acerca dos fatores que determinam a estabilidade e a funcionalidade dos nanobioconjugados (NBCs). Assim, nesta tese buscamos compreender os fatores responsáveis pela ligação/adsorção das proteínas nas nanopartículas de ouro e sua influência sobre a estabilidade das suspensões e a funcionalidade das proteínas. Desta forma, foram obtidos NBCs com propriedades adequadas para o desenvolvimento ou aprimoramento de ensaios de diagnóstico e até para o tratamento de doenças. Foi demonstrado o potencial das nanopartículas de ouro para melhorar a performance de imunoensaios do tipo ELISA, mas também podem ser utilizadas para o desenvolvimento de métodos de diagnóstico, explorando as propriedades plasmônicas das nanopartículas de ouro acopladas a técnicas como SERS, SPR e microscopia Raman confocal. / Theranostics has been intensively pursued in recent years using hybrid materials based on nanoparticles conjugated with biomolecules. This is an interesting strategy to increase the selectivity and sensitivity, as well as to improve the currently used methods facilitating their use or creating new ones. Among the various types of nanomaterials, those based on gold and magnetic nanoparticles exhibit interesting chemical and physical properties in the biological environment, differing from that of free drugs or current explored in assay methods. For example, superparamagnetic nanoparticles are excellent contrast agents for magnetic resonance image (MRI) diagnostics because they are safer, present a better contrast efficiency for imaging and can be magnetically accumulated in tissues or tumors using a magnetic field. Numerous in vitro and in vivo toxicity assays were performed to ensure the safety for medical applications. Clearly, these type of applications only will be realized if nanomaterials prove to be nontoxic and biocompatible. This imply an strict control on their structure and composition. However, despite the significant advances in the development of such nanomaterials, there were not found in the literature model systems explaining or that can be used to predict by which sites the protein-nanoparticle binding should take place. In addition, no systematic studies on the factors determining the stability and the functionality of nanobioconjugates (NBC) were found. Thus, this thesis is focused in unveiling the factors responsible for binding/adsorption of proteins on gold nanoparticles and their influence on the colloidal stability of hybrid nanoparticles suspensions while keeping the functionality of biomolecules. In fact, NBC with enhanced properties suitable for the development of diagnostic methods and even for treatment of diseases were obtained. These nanomaterials can improve the ELISA immunoassay, or other diagnosis methods can be developed by using the gold nanoparticles plasmonic properties in association with SERS, SPR and confocal Raman microscopy techniques.

The hydrophobicity of a surface is an important property in many areas of science and engineering. This is especially the case in mineral processing, where differences in surface hydrophobicity lie at the heart of the separation process of flotation. Chemicals are used to increase and decrease the natural hydrophobicity of minerals to attain a better separation between valuable and worthless material. Polymers are often used to reduce mineral surface hydrophobicity. Decades of empirically based decision making have produced a list of effective depressants. However the detailed study of how these polymer depressants affect surface hydrophobicity and mineral recovery lags behind applied investigations. The aim of this thesis was to study the adsorption of commonly used depressants on model surfaces and to interrogate the action of these polymers in reducing surface hydrophobicity. We have modelled the degree of hydrophobicity of common minerals in order to study polymer depressants with methods not commonly used in studies of surface characterisation in flotation. The model surfaces (self-assembled monolayers, SAMs) allowed us to use the quartz crystal microbalance with dissipation monitoring (QCM-D) to study the adsorption of polymers. The QCM-D can be used to obtain adsorption isotherms, adsorption kinetics, water content of adsorbed layers, and information on the conformation of the adsorbed polymer. The results from the QCM-D were correlated with the contact angle data from the captive bubble measurements, with which we assessed the hydrophobicity of the surface before and after polymer adsorption. Three of the polymers layers were probed with dynamic dewetting studies, in order to test other modes of depressant action. Three types of polymers were studied - a polyacrylamide (Polymer-H), a polyelectrolyte CMC (carboxymethyl cellulose) and a group of dextrins (Dextrin-TY, a phenyl succinate substituted dextrin (PS Dextrin) and a styrene oxide substituted dextrin (SO Dextrin)). These polymers are commonly used or have potential to be used in the depression of talc and graphite. Polymer-H was used to investigate the hydrophobic bonding between a non-ionic polymer depressant and chemically inert and non charged surfaces by probing the influence of substrate hydrophobicity on polymer adsorption and reduction of contact angle. Three different model surfaces were used (mixed self-assembled 0.5 SAM, 0.7 SAM or single self-assembled 1.0 SAM monolayers) with advancing contact angles between 75?? and 119??. The study of Polymer-H found that the substrate hydrophobicity is an important factor in adsorption of this polymer and the change in contact angle upon adsorption depends on adsorbed amount. The effectiveness of Polymer-H to reduce surface hydrophobicity was established to correlate with its conformation and morphology. CMC was investigated to find out how a stimulus responsive polymer depressant can be used in flotation. It was established that the adsorbed amount and rate of adsorption of CMC increase with decreasing of pH or increasing of ionic strength. It was shown that the surface hydrophobicity of a CMC pre-adsorbed layer changes with the environment and these alterations are fully reversible. A switch of ionic strength (from 10-2 M KCl to 10-1 M KCl) caused partial dehydration of the adsorbed layer and a decrease of the receding contact angle by 20??. A pH switch (pH = 9 to pH = 3) resulted in a 40?? change in receding contact angle. The CMC investigation showed that the use of a stimulus responsive polymer presents opportunities for exploiting solution conditions as a means to effect a better mineral separation in flotation The adsorption of three dextrin-based polymers on a model hydrophobic surface has been characterized using the quartz crystal microbalance with dissipation monitoring (QCM-D). The three polymers (one standard dextrin and two dextrins with different aromatic group substitutions) exhibited varying affinities and capacity for adsorption on the hydrophobic substrate. The effect of the three polymers on the static contact angle of the surface was studied using captive bubble contact angle measurements. The three polymers were seen to reduce the receding contact angle by similar amounts (approximately 14 degrees) in spite of having varying adsorbed amounts and differences in adsorbed layer water content. Although no differences were observed in the ability of the polymers to reduce the static contact angle, measurements of the dewetting dynamics between a rising air bubble and the polymer covered substrate yielded stark differences between the polymers, with one polymer slowing the dewetting dynamics by an order of magnitude more than the other two polymers. The differences in dewetting behaviour correlate with the adsorbed layer characteristics determined by QCM-D. / Thesis (PhD)--University of South Australia, 2010