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Interfacial adsorption of proteins : a neutron reflectivity studyLatter, Edward Gareth January 2012 (has links)
Protein adsorption at the solid/liquid interface is of wide ranging importance in many different areas of science such as biomaterial design, the fate of nanoparticles and in the food industry. As a result, many studies have been undertaken with varying foci but there still remains a lack of agreement between many working in this field and fundamental questions regarding the adsorption of proteins at the solid/liquid interface. Neutron reflectivity is a powerful technique for probing the properties of adsorbed layers at interfaces due to its high structural resolution and the possibility of using isotopic substitution to distinguish between components of a mixture. In this work, neutron reflectivity has been used as the primary technique for the investigation of proteins adsorbed sequentially or from a binary mixture. Initially, the adsorption of four proteins (carbonic anhydrase II, lysozyme, human serum albumin and maltose binding protein) onto a clean silica surface was investigated which revealed the importance of electrostatic interactions and entropic contributions to the driving forces for adsorption. Most of the adsorbed layers were described by a 2-layer model with a thinner, denser layer adjacent to the surface and a thick, diffuse layer extending into the bulk solution. The presence of impurities is also shown to have a significant impact on the adsorption of HSA. A study of the HSA/myristic acid system shows that the presence of small amphiphiles can inhibit HSA adsorption and also remove a pre-adsorbed layer. A comparison was made between the protonated and deuterated forms of two proteins, HSA & MBP, showing the deuterated proteins to have a higher affinity for the surface with adsorption occurring in a 3:1 ratio when from a 1:1 mixture. Likewise, d-MBP displaced h-MBP more readily than vice versa in an investigation into the effect of incubation time on the properties of the protein layer. The extent of desorption into protein free buffer is not affected by incubation time but the extent to which d-MBP was displaced by h-MBP showed a clear trend of decreased exchange with increasing incubation time indicating an active exchange process was occurring. This was also observed to a lesser extent for the sequential adsorption of binary protein systems, HSA & LYS and HSA & MBP. When investigating binary protein mixtures the higher propensity for deuterated proteins to adsorb is observed. LYS dominates when adsorbed from a mixture with h-HSA but from a d-HSA & LYS mix both proteins were adsorbed. The marked difference between the adsorption characteristics of perdeuterated proteins and their protonated counterparts provides a good case study for testing the neutron reflectivity technique when investigating systems with more than one component. This thesis assesses the limitations of the methodology of contrast variation for investigating mixtures as well as using different solvent contrasts. A comparison of neutron reflectivity and dual polarisation interferometry (DPI) shows that the two techniques are similar and any small differences can be attributed to the small change in surface chemistry. This comparison also highlights the advantages of DPI; high throughput of samples and detailed information but the restriction to using a 1-layer model limits its use.
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Hydrogen terminated silicon surfaces: Development of sensors to detect metallic contaminants and stability studies under different environmentsPonnuswamy, Thomas Anand 08 1900 (has links)
Hydrogen terminated silicon surfaces have been utilized to develop sensors for semiconductor and environmental applications. The interaction of these surfaces with different environments has also been studied in detail. The sensor assembly relevant to the semiconductor industry utilizes a silicon-based sensor to detect trace levels of metallic contaminants in hydrofluoric acid. The sensor performance with respect to two non-contaminating reference electrode systems was evaluated. In the first case, conductive diamond was used as a reference electrode. In the second case, a dual silicon electrode system was used with one of the silicon-based electrodes protected with an anion permeable membrane behaving as the quasi reference electrode. Though both systems could function well as a suitable reference system, the dual silicon electrode design showed greater compatibility for the on-line detection of metallic impurities in HF etching baths. The silicon-based sensor assembly was able to detect parts- per-trillion to parts-per-billion levels of metal ion impurities in HF. The sensor assembly developed for the environmental application makes use of a novel method for the detection of Ni2+using attenuated total reflection (ATR) technique. The nickel infrared sensor was prepared on a silicon ATR crystal uniformly coated by a 1.5 micron Nafion film embedded with dimethylglyoxime (DMG) probe molecules. The detection of Ni2+ was based on the appearance of a unique infrared absorption peak at 1572 cm-1 that corresponds to the C=N stretching mode in the nickel dimethylglyoximate, Ni(DMG)2, complex. The suitable operational pH range for the nickel infrared sensor is between 6-8. The detection limit of the nickel infrared sensor is 1 ppm in the sample solution of pH=8. ATR - FTIR spectroscopy was used to study the changes that the hydride mode underwent when subjected to different environments. The presence of trace amounts of Cu2+ in HF solutions was found to roughen the silicon surface as observed ATR-IR spectroscopy. The initial stages of oxidation in UPW and Cu2+ / UPW was studied. Trace amounts of Cu2+ were found to drastically increase the rate of oxidation, while the rate of oxidation was found to be retarded on removing dissolved oxygen that was present in UPW.
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Study of Interactions Between Diffusion Barrier Layers and Low-k Dielectric Materials for Copper/Low-k IntegrationTong, Jinhong 12 1900 (has links)
The shift to the Cu/low-k interconnect scheme requires the development of diffusion barrier/adhesion promoter materials that provide excellent performance in preventing the diffusion and intermixing of Cu into the adjacent dielectrics. The integration of Cu with low-k materials may decrease RC delays in signal propagation but pose additional problems because such materials are often porous and contain significant amounts of carbon. Therefore barrier metal diffusion into the dielectric and the formation of interfacial carbides and oxides are of significant concern. The objective of the present research is to investigate the fundamental surface interactions between diffusion barriers and various low-k dielectric materials. Two major diffusion barriers¾ tatalum (Ta) and titanium nitride (TiN) are prepared by DC magnetron sputtering and metal-organic chemical vapor deposition (MOCVD), respectively. Surface analytical techniques, such as X-ray photoelectronic spectroscopy (XPS), transmission electron microscopy (TEM), and atomic force microscopy (AFM) are employed.
Ta sputter-deposited onto a Si-O-C low dielectric constant substrate forms a reaction layer composed of Ta oxide and TaC. The composition of the reaction layer varies with deposition rate (1 Å-min-1 vs. 2 Å-sec-1), but in both cases, the thickness of the TaC layer is found to be at least 30 Å on the basis of XPS spectra, which is corroborated with cross-sectional TEM data. Sputter-deposited Cu will not wet the TaC layer and displays facile agglomeration, even at 400 K. Deposition for longer time at 2 Å-sec-1 results in formation of a metallic Ta layer. Sputter deposited Cu wets (grows conformally) on the metallic Ta surface at 300 K, and resists significant agglomeration at up to ~ 600 K. Cu diffusion into the substrate is not observed up to 800 K in the UHV environment.
Tetrakis(diethylamido) titanium (TDEAT) interactions with SiO2, Cu and a variety of low-k samples in the presence (~ 10-7 Torr or co-adsorbed) and absence of NH3 result in different products. TDEAT interactions with SiO2 are dominated by Ti interactions with substrate oxygen sites, and that Ti oxide/sub-oxide bond formation can proceed with relatively low activation energy. No Ti carbide or Si carbide formation is observed. Co-adsorption of TDEAT and NH3 on SiO2 at 120K followed by annealing to higher temperature results in enhanced Ti-N bond formation, which is stable against oxidation up to 900K in UHV. Similarly, continuous exposures of TDEAT on SiO2 at 500K in the presence of NH3 exhibit a relatively enhanced Ti-N spectral component. Co-adsorption of NH3 and TDEAT on Cu (poly) surface at 120K, followed by annealing to 500K, results in complete desorption of Ti, N or C-containing species from the Cu substrate. Reaction of TDEAT with a Cu surface at 500K yields a Ti-alkyl species via a b-hydride elimination pathway. TDEAT/Cu interactions are not observably affected by overpressures of NH3 of 10-7 Torr. TDEAT interaction with a porous carbon doped oxide low-k substrate at 700K demonstrates undissociated or partly dissociated Ti-NR species trapped in the dielectrics matrix due to its high porosity. In addition, carbide formation is observed from C(1s) XPS spectra. For a hydrocarbon low-k film, the majority sites (carbon) are highly unreactive towards TDEAT even at higher temperature due to a lack of functional groups to initiate the TDEAT/low-k surface chemistry.
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Bilayer formation with fluorinated amphiphiles and applications in membrane protein studiesRaychaudhuri, Pinky January 2013 (has links)
Every cell is enclosed by a membrane which gives structure to the cell and allows for the passage of nutrients and wastes into and out of the cell. Membranes are made up of amphiphilic lipid molecules, with one water-soluble end, and one hydrophobic end. Naturally occurring and synthetic membranes are made up of double-chained amphiphiles derived from hydrocarbons. Recently, a novel class of amphiphilic molecules derived from fluorocarbons have been reported. The properties of fluorinated amphiphiles are very different to that of hydrocarbon based amphiphiles. Fluorinated amphiphiles have been previously reported to be useful in the studies of membrane proteins. In this thesis, we explore some novel uses of fluorinated amphiphiles. <b>Chapter one</b>: Provides a comprehensive review of the properties of fluorocarbon-based amphiphiles and discusses the existing uses of fluorinated amphiphiles in biochemical and biomedical research. <b>Chapter two</b>: Describes some of the important materials and methods used in this thesis including a detailed description of the proteins used and the working principles behind the techniques used in the study. <b>Chapter three</b>: Looks at the stability of pre-formed planar lipid bilayers in the presence of fluorinated amphiphiles (F-amphiphiles), and characterizes the behaviour of alpha-haemolysin and other proteins in liposomes and planar lipid bilayers in the presence of F-amphiphiles. We found that F-amphiphiles have an inhibitory effect on the insertion of protein into lipid bilayers, and this property has been exploited to control the number of proteins in the bilayer. <b>Chapter four</b>: Using droplet interface bilayers, we investigate the electrical properties and behaviour of protein(s) in bilayers formed by F-amphiphiles. The results obtained with fluorinated bilayers are compared with results obtained in conventional DPhPC lipid bilayers. This is the first ever report to carry out such an investigation and it provides insights into the formation, stability and utility of fluorinated bilayers. <b>Chapter five</b>: In Chapter five, we explore another aspect of droplet interface bilayers: the feasibility of using droplet interface bilayers to screen for membrane protein libraries. I have chosen to focus on certain fundamental aspects of the screening process that are sufficient to establish the feasibility of the method and to act as the proof of concept. <b>Chapter six</b>: Summarizes all the important results in the thesis and discusses some possible future directions of this project.
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Modifications de surface des nanodiamants : compréhension des mécanismes d’échanges électroniques et mise en évidence d’un effet thérapeutique / Nanodiamonds surface modifications : understanding of electron exchange mecanisms and evidence of a therapeutic effectPetit, Tristan 18 March 2013 (has links)
A partir de l'étude des effets de la chimie de surface des Nanodiamants (NDs) sur leurs propriétés électroniques, cette thèse a permis la mise en évidence d'un effet thérapeutique des NDs sur des cellules humaines. En particulier, il a été montré que les NDs de détonation peuvent générer des radicaux libres oxygénés sous radiation ionisante, ce qui pourrait améliorer l'efficacité de certains traitements de radiothérapie actuels. Les échanges électroniques entre le coeur des NDs et leur environnement sont en effet favorisés après des traitements de surface, notamment d'hydrogénation et de graphitisation de surface. Les conditions expérimentales permettant d'obtenir des NDs hydrogénées (NDs-H) sous plasma d'hydrogène ont été optimisées sous ultravide, puis ont été utilisées pour préparer de grandes quantités de NDs-H sous forme pulvérulente. La même procédure a été appliquée pour la graphitisation de surface des NDs, en utilisant des recuits sous vide à haute température. L'effet de ces traitements de surface sur les propriétés d'interactions électroniques des NDs a été étudié après exposition à l'air ambiant, puis en dispersion dans l'eau. Ces traitements de surface assurent notamment un potentiel Zeta positif aux NDs, dont l'origine a été discutée. Enfin, les interactions des NDs avec plusieurs lignées de cellules tumorales humaines ont été étudiées et l'efficacité des NDs pour radiosensibiliser des cellules radiorésistantes sous irradiation gamma a été montrée, ouvrant de nouvelles perspectives d'applications des NDs en nanomédecine. . / In this thesis, a therapeutic effect of nanodiamonds (NDs) has been evidenced by investigating the role of NDs surface chemistry on their electronic properties. More precisely, the generation of reactive oxygen species from detonation NDs under ionizing radiation, which could improve current radiotherapy treatments, has been demonstrated. To this end, surface treatments facilitating electron transfer from NDs to their environment, namely hydrogenation and surface graphitization, were developed. Experimental conditions ensuring an efficient hydrogenation by hydrogen plasma were determined under ultrahigh vacuum, before being used to prepare large quantities of NDs in powder phase. A similar procedure was applied to the surface graphitization of NDs, performed by annealing under vacuum at high temperature. The impact of such surface treatments on the electronic interaction properties of NDs has been investigated under ambient air and after dispersion in water. These surface treatments induce a positive Zeta potential to NDs in water, which origin has been discussed. Finally, their interactions with human tumor cells were observed. Radiosensitization of tumor cells using NDs under gamma irradiation was demonstrated, opening new perspectives for NDs in nanomedicine.
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Method development for the application of vibrational spectroscopy to complex organic-inorganic materials in astrobiology : a systematic development of Raman spectroscopy and related analytical methods to the structural chemistry at organic (biological) and inorganic (mineralogical) interfaces of material assemblies relevant to astrobiology and inter-planetary scienceWhitaker, Darren Andrew January 2013 (has links)
In the search for the conformation of extant or extinct life in an extraterrestrial setting the detection of organic molecular species which may be considered diagnostic of life is a key objective. These molecular targets comprise a range of distinct chemical species, with recognisable spectroscopic features. This project aims to use these features to develop an in-situ molecular specific Raman spectroscopic methodology which can provide structural information about the organic–inorganic interface. The development of this methodology identified a surface enhanced Raman spectroscopic technique, that required minimal sample preparation, allowed for the detection of selected organic species immobilised on an inorganic matrix and was effective for quantities below those which conventional dispersive Raman spectroscopy would detect. For the first time spectral information was gained which allowed analysis of the organic–inorganic interface to be carried out, this gave an insight into the orientation with which molecules arrange on the surfaces of the matrices. Additionally a method for the detection of organic residues intercalated into the interlamellar space of smectite type clays was developed. An evaluation of the effectiveness of uni and multivariate methods for the analysis of large datasets containing a small number of organic features was also carried out, with a view to develop an unsupervised methodology capable of performing with minimal user interaction. It has been shown that a novel use of the Hotellings T2 test when applied to the principal component analysis of the datasets combined with SERS allows identification of a small number of organic features in an otherwise inorganic dominated dataset. Both the SERS and PCA methods hold relevance for the detection of organic residues within interplanetary exploration but may also be applied to terrestrial environmental chemistry.
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Effect of particle size distribution on activated carbon adsorptionKunjupalu, Thoppil Jojo. January 1986 (has links)
Call number: LD2668 .T4 1986 K86 / Master of Science / Civil Engineering
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A Multi-Method Approach for the Quantification of Surface Amine Groups on Silica NanoparticlesSun, Ying 29 July 2019 (has links)
As nanomaterials continue to garner interest in a wide range of industries and
scientific fields, commercial suppliers have met growing consumer demand by readily
offering custom particles with size, shape and surface functionality made-to-order. By
circumventing the challenging and complex synthesis of functionalized nanoparticles,
these businesses seek to provide greater access for the experimentation and
application of these nanoscale platforms.
In many cases, amine functional groups are covalently attached as a surface
coating on a nanoparticle to provide a starting point for chemical derivatization and
commonly, conjugation of biomolecules in medical science applications. Successful
conjugation can improve the compatibility, interfacing and activity of therapeutic and
diagnostic nanomedicines. Amines are amongst the most popular reactive groups used
in bioconjugation pathways owing to the many high-yield alkylation and acylation
reaction are involved in.
For the design of functionalized nanomaterials with precisely tuned surface
chemical properties, it is important to develop techniques and methods which can
accurately and reproducibly characterize these materials. Quantification of surface
functional groups is crucial, as these groups not only allow for conjugation of chemical
species, but they also influence the surface charge and therefore aggregation behavior
of nanomaterials. The loss of colloidal stability of functionalized nanomaterials can often
correspond to a significant if not complete loss of functionality.
Thus, we sought to develop multiple characterization approaches for the
quantification of surface amine groups. Silica nanoparticles were selected as a model
nanomaterial as they are widely used, commercially available, and their surface
chemistry has been investigated and studied for decades. Various commercial batches
of silica nanoparticles were procured with sizes ranging from 20 – 120 nm. Two
colorimetric assays were developed and adapted for their ease-of-use, sensitivity, and
convenience. In addition, a fluorine labelling technique was developed which enabled
analysis by quantitative solid-state 19F NMR and X-ray photoelectron spectroscopy
(XPS). XPS provided data on surface chemical composition at a depth of ≈ 10 nm,
which allowed us to determine coupling efficiencies of the fluorine labelling technique
and evaluate the reactivity of the two assays.
The ensemble of surface-specific quantification techniques was used to evaluate
multiple commercial batches of aminated silica and investigate batch-to-batch variability
and the influence of particle size with degree of functionalization. In addition, resulting
measurements of surface amine content were compared and validated by an
independent method based on quantitative solution 1H NMR, which was developed for
total functional group content determination. This allowed for us to assess the role of
accessibility and reactivity of the amine groups present in our silica particles.
Overall, the objective of this study was to develop a multi-method approach for
the quantification of amine functional groups on silica nanoparticles. At the same time,
we hoped to set a precedent for the development and application of multiple
characterization techniques with an emphasis of comparing them on the basis of
reproducibility, sensitivity, and mutual validation.
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Propriedades da N, N-DI (2-fosfonoetil) naftaleno diimida em solução e em filmes auto-montados à base de zircônio / Properties of N, N\'-DI (2-phosphonoethyl) naphthalene diimide in solution and in self-assembled zirconium-based filmsRodrigues, Magali Aparecida 14 July 2000 (has links)
Sintetizou-se uma nova diimida naftálica difosfônica, a N, N-bis(2-fosfonetil)naftaleno diimida (DPN), pela reação do dianidrido 1,4,5,5-naftálico com o ácido 2-aminoetil-fosfônico. Essa molécula foi caracterizada por H-RMN, micro-análise, titulação potenciométrica e análise de fosfato. Através de estudos fotofísicos e fotoquímicos do DPN em solução verificou-se que essas moléculas encontravam-se na forma monomérica em água e na forma de agregados em solventes orgânicos. Verificou-se que o rendimento quântico de fluorescência Φf dessa molécula é dependente do pH do meio, uma vez que ocorre diminuição do Φf com aumento do pH. Por estudos com fotólise de relâmpago e por experimentos de lente térmica resolvida no tempo, verificou-se que a diminuição do Φf com aumento do pH. Por estudos com fotólise de relâmpago e por experimentos de lente térmica resolvida no tempo, verificou-se que a diminuição Φf é causada principalmente por um aumento no cruzamento intersistema, de singleto a tripleto. Multicamadas à base de zircônio (Mallouk et al. 1987) do DPN foram obtidas substratos como vidro, silício e ouro. O crescimento de filmes em vidro foi acompanhado por espectroscopia de absorção e em filmes sobre o silício por elipsometria. Sobre a superfície de ouro, foram estudadas as propriedades de oxido-redução do filme por voltametria cíclica. Por estudos fotofisicos desses filmes depositados em vidro, verificou-se que os mesmos eram fotoativos, formando produtos fotoquímicos por processos radicalares. Por outro lado, quando se preparou micro-cristais, pricipitando-se o radical do DPN com o zircônio em solução, observou-se por espectroscopia de ressonância de spin eletrônico (EPR) que estas estruturas micro-cristalinas estabilizavam o radical do DPN em presença de ar por vários dias. / The new diimide N, N\' -bis-(2-phosphoethyl)-1,4,5,8-naphtalenediimide (DPN) was synthesized by reaction of 2-aminoethylphosphonic acid with the compound 1,4,5,8-naphatalene tetracarboxylic dianhydride. This molecule was characterized by 1H-RMN, elemental analysis, potentiometric titration and phosphorus analysis. By photophysical and photochemical studies of DPN in solution, it was verified that DPN is in monomeric form in aqueous solution and DPN is in an aggregated state in organic solvents. When the fluorescence spectra in aqueous media show a sharp decrease in the fluorescence quantum yield (Φf) with the increase in pH. By laser flash photolysis and thermal lensing, it was verified that this reduction of Φf with the increase pH can be attributed to an increment in the intersystem crossing processes when the pH increased. The zirconium phosphonate thin films formed from 1,4,5,8-naphtalene diimides were assembled on quartz, borosilicate glass (BK7), silicon or gold. The film growth was followed by absorption spectroscopy on quartz and BK7 and by ellipsometry on silicon substrate. Toe oxidation and reduction properties of the films were studied by cyclic voltammetry of films deposited on gold. Photophysical and photochemical data revealed that the films were photosensitive, giving rise to products derived by radicalar reactions. On the other hand, when the DPN radical was precipitated with Zr4+ in solution, micro-crystals were obtained which stabilized the radical in the presence of air for several days.
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Nanopartículas multifuncionais dispersáveis e suas potenciais aplicações em nanomedicina / Dispersable Multifunctional Nanoparticles and Their Potential Aplications in NanomedicineCardoso, Roberta Mansini 27 June 2018 (has links)
O design de materiais na escala nanométrica está levando a sistemas com novas propriedades e aplicações as mais diversas, como em sistemas de diagnóstico e de tratamento inteligentes e sustentáveis. Melhorar a eficiência dos tratamentos de doenças através do desenvolvimento de fármacos mais eficientes e com menos efeitos colaterais, e agentes de contraste e de diagnóstico mais específicos e sensíveis para monitoramento preventivo precoce, é um dos principais objetivos da Nanomedicina. Todavia, a química de superfície necessária para realizar tais reações de funcionalização/conjugação de moléculas ainda está longe de ser adequadamente controlada, particularmente considerando-se a complexidade das biomoléculas e a estabilidade coloidal. Assim, nesta tese foram desenvolvidos processos de conjugação de nanopartículas de óxido de ferro (SPIONs) com um ou mais agentes co-funcionalizantes, gerando partículas mono, bi e multifuncionalizadas dispersáveis em meio aquoso. Os esforços foram concentrados no desenvolvimento de sistemas de diagnóstico e de entrega de fármacos baseados em nanopartículas, cujas propriedades precisam ser ajustadas pela conjugação de biomoléculas e espécies bioativas em sua superfície, num verdadeiro trabalho de engenharia a nível nanométrico/molecular. De fato, nanopartículas modificadas com moléculas co-funcionalizantes estabilizantes (glicerol-fosfato, glicose-fosfato, fosforiletanolamina, dopamina e tiron), agentes de vetorização que direcionam o nanoconjugado a células-alvo tumorais (ácido fólico e biotina), bem como com fármacos como metotrexato e ibuprofeno foram preparadas, e o efeito das mesmas sobre a eficiência de incorporação por células tumorais (HeLa e MCF-7) estudada. Os estudos de atividade biológica in vitro foram realizados em parceria com o Laboratório de Processos Fotoinduzidos e Interfaces (LPFI-IQUSP). Os resultadosobtidos confirmaram a possibilidade de se controlar a atividade biológica das nanopartículas por meio dos agentes funcionalizantes, abrindo perspectivas interessantes para o desenvolvimento de nanoagentes multifuncionais para teranóstica, conjugados com agentes de vetorização específicos (particularmente anticorpos e aptâmeros), além de agentes de contraste (radiofármacos, fluoróforos, contraste para IRM, etc.) e moléculas terapêuticas (antitumorais, anti-inflamatórios, dentre outros). Entretanto, diversos são os problemas associados aos processos químicos envolvendo a produção e funcionalização desses nanomateriais por processos convencionais em batelada, que tendem a ser demorados e apresentam dificuldade de controle dos parâmetros de reação e baixa reprodutibilidade, dificultando o escalonamento produtivo e a comercialização dos eventuais produtos. Uma estratégia promissora é o uso de reatores microfluídicos com projeto de canais adequado, além de atuadores e sensores que, juntos garantam excelente controle de processos e baixo consumo de energia e de reagentes. Assim, também foram desenvolvidos reatores microfluídicos para produção e funcionalização de nanopartículas de ouro, de forma a tornar os processos químicos programáveis, mais eficientes, controláveis e econômicos, em parceria com o Laboratório de Micromanufatura do Instituto de Pesquisas Tecnológicas (LMI-BIONANO/IPT). Essa parte do desenvolvimento foi realizando empregando a tecnologia de microfabricação em Low Temperature Co-fired Ceramics (LTCC), uma tecnologia versátil que possibilita a produção de dispositivos de diferentes geometrias em materiais cerâmicos de baixa reatividade e de baixo custo. Esses dispositivos podem tornar os processos de produção de nanopartículas multifuncionais dispersáveis suficientemente simples, versáteis e reprodutíveis para atender aos altos padrões de qualidade exigidos para produtos voltados para aplicações biomédicas / Materials design at nanoscale is leading us to intelligent systems with new properties and applications, such as more efficient diagnostic and treatment systems. Improving the treatment of diseases by the development of more specific and efficient drugs, displaying fewer or no side effects, conjugated with sensitive contrast/diagnostic agents for early preventive monitoring and treatment is one of the main goals of the Nanomedicine. However, the knowledge on surface chemistry required to perform such molecular functionalization/conjugation reactions still is far from being adequately controlled, particularly considering the complexity of biomolecules and reaching colloidal stability. Thus, in this thesis, processes of conjugation of iron oxide nanoparticles (SPIONs) with one or more co-functionalizing agents have been developed so as to generate mono, bi and multi-particles dispersible in aqueous medium. Efforts were specifically focused on the development of drug delivery and diagnostic systems based on nanoparticles whose properties must be adjusted by the conjugation of biomolecules and bioactive species on their surface, in a truly nano/molecular scale engineering work. In fact, nanoparticles modified with stabilizing co-functionalizing molecules (glycerolphosphate, glucose-phosphate, phosphorylethanolamine, dopamine and tiron), targeting agents (folic acid and biotin) to guide itself and concentrate in specific tumor cells, as well as with drugs such as methotrexate and ibuprofen were prepared, and their effect on the efficiency of uptake by tumor cells (HeLa and MCF-7) studied. In vitro biological activity studies were performed in collaboration with the Laboratory of Photo Induced Processes and Interfaces (LPFI-IQUSP). The results confirmed the possibility of controlling the biological activity of nanoparticles by anchoring suitable functionalizing agents in an additive way, opening interesting new perspectives for the development ofmultifunctional theranostics nanoagents, conjugated with specific vectorization agents (particularly antibodies and aptamers), as well as diagnostic (radiopharmaceuticals, fluorophores, MRI contrast, etc.) and therapeutic agents (antitumor, anti-inflammatory, among others). However, there are several problems associated with the production and functionalization of these nanomaterials by conventional batch processes, which tend to be time consuming and difficult to control, as confirmed by their low reproducibility, making it difficult to produce and commercialize the eventual products. A promising strategy is the use of microfluidic reactors with suitable channel designs, as well as actuators and sensors that, together, ensure excellent process control and low energy and reagent consumption. Thus, microfluidic reactors were also developed for the production and functionalization of gold nanoparticles in order to make chemical processes more predictable, efficient, controllable and economical, in partnership with the Micromanufacturing Laboratory of the Institute of Technological Research (LMI-BIONANO/IPT). This part of the development was accomplished by employing the Low Temperature Co-fired Ceramics (LTCC) microfabrication technology, a versatile technology that enables the production of devices of different geometries in ceramic materials of low reactivity and of low cost. These devices can make the production processes of dispersible multifunctional nanoparticles simple, versatile and reproducible enough to meet the high standards of quality required for products for biomedical applications
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