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Protein Microparticles for Printable BioelectronicsNadhom, Hama January 2015 (has links)
In biosensors, printing involves the transfer of materials, proteins or cells to a substrate. It offers many capabilities thatcan be utilized in many applications, including rapid deposition and patterning of proteins or other biomolecules.However, issues such as stability when using biomaterials are very common. Using proteins, enzymes, as biomaterialink require immobilizations and modifications due to changing in the structural conformation of the enzymes, whichleads to changes in the properties of the enzyme such as enzymatic activity, during the printing procedures andrequirements such as solvent solutions. In this project, an innovative approach for the fabrication of proteinmicroparticles based on cross-linking interchange reaction is presented to increase the stability in different solvents.The idea is to decrease the contact area between the enzymes and the surrounding environment and also preventconformation changes by using protein microparticles as an immobilization technique for the enzymes. The theory isbased on using a cross-linking reagent trigging the formation of intermolecular bonds between adjacent proteinmolecules leading to assembly of protein molecules within a CaCO3 template into a microparticle structure. TheCaCO3 template is removed by changing the solution pH to 5.0, leaving behind pure highly homogenous proteinmicroparticles with a size of 2.4 ± 0.2 μm, according to SEM images, regardless of the incubation solvents. Theenzyme model used is Horse Radish Peroxidase (HRP) with Bovine Serum Albumin (BSA) and Glutaraldehyde (GL)as a cross-linking reagent. Furthermore, a comparison between the enzymatic activity of the free HRP and the BSAHRPprotein microparticles in buffer and different solvents are obtained using Michaelis-Menten Kinetics bymeasuring the absorption of the blue product produced by the enzyme-substrate interaction using a multichannelspectrophotometer with a wavelength of 355 nm. 3,3’,5,5’-tetramethylbenzidine (TMB) was used as substrate. As aresult, the free HRP show an enzymatic activity variation up to ± 50 % after the incubation in the different solventswhile the protein microparticles show much less variation which indicate a stability improvement. Moreover, printingthe microparticles require high microparticle concentration due to contact area decreasing. However, usingmicroparticles as a bioink material prevent leakage/diffusion problem that occurs when using free protein instead.
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A novel bio-stable 3D porous collagen scaffold for implantable biosensorJu, Young Min. January 2008 (has links)
Thesis (Ph. D.)--University of South Florida, 2008. / Title from PDF of title page. Document formatted into pages; contains 133 pages. Includes vita. Includes bibliographical references.
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Micropart?culas polim?ricas ? base de xilana e Eudragit? S-100 contendo mesalazina visando ? libera??o c?lon-espec?ficaSilva, Acarilia Eduardo da 10 March 2009 (has links)
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Previous issue date: 2009-03-10 / Conselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico / Colon-specific drug delivery systems have attracted increasing attention from the
pharmaceutical industry due to their ability of treating intestinal bowel diseases (IBD), which
represent a public health problem in several countries. In spite of being considered a quite
effective molecule for the treatment of IBD, mesalazine (5-ASA) is rapidly absorbed in the
upper gastrointestinal tract and its systemic absorption leads to risks of adverse effects. The
aim of this work was to develop a microparticulate system based on xylan and Eudragit? S-
100 (ES100) for colon-specific delivery of 5-ASA and evaluate the interaction between the
polymers present in the systems. Additionaly, the physicochemical and rheological properties
of xylan were also evaluated. Initially, xylan was extracted from corn cobs and characterized
regarding the yield and rheological properties. Afterwards, 10 formulations were prepared in
different xylan and ES100 weight ratios by spray-drying the polymer solutions in 0.6N NaOH
and phosphate buffer pH 7.4. In addition, 3 formulations consisting of xylan microcapsules
were produced by interfacial cross-linking polymerization and coated by ES100 by means of
spray-drying in different polymer weight ratios of xylan and ES100. The microparticles were
characterized regarding yield, morphology, homogeneity, visual aspect, crystallinity and
thermal behavior. The polymer interaction was investigated by infrared spectroscopy. The
extracted xylan was presented as a very fine and yellowish powder, with mean particle size
smaller than 40μm. Regarding the rheological properties of xylan, they demonstrated that this
polymer has a poor flow, low density and high cohesiveness. The microparticles obtained
were shown to be spherical and aggregates could not be observed. They were found to present
amorphous structure and have a very high thermal stability. The yield varied according to the
polymer ratios. Moreover, it was confirmed that the interaction between xylan and ES100
occurs only by means of physical aggregation / Sistemas c?lon-espec?ficos t?m atra?do o interesse da ind?stria farmac?utica devido ?
possibilidade de tratarem enfermidades, como as doen?as inflamat?rias intestinais (DII), que
compreendem um problema de sa?de p?blica em muitos pa?ses. Apesar de ser considerada
uma mol?cula bastante eficiente para o tratamento das DII, a mesalazina (5-ASA) ?
rapidamente absorvida no trato gastrintestinal superior e sua absor??o sist?mica leva ?
incid?ncia de s?rios efeitos adversos. Este trabalho teve como objetivos produzir um sistema
polim?rico microparticulado ? base de xilana e Eudragit? S-100 (ES100) para libera??o
c?lon-espec?fica de 5-ASA e avaliar a intera??o entre os pol?meros constituintes do sistema,
al?m de aprofundar a caracteriza??o f?sico-qu?mica e tecnol?gica da xilana. A xilana foi
extra?da a partir de sabugos de milho e caracterizada quanto ao rendimento, granulometria,
cristalinidade, propriedades reol?gicas e comportamento t?rmico. Em seguida, 10
formula??es contendo 5-ASA foram preparadas em diferentes propor??es de xilana e ES100
atrav?s da secagem por aspers?o das solu??es polim?ricas com NaOH 0,6N ou tamp?o-fosfato
pH 7,4, como solvente. Al?m disso, 3 formula??es constitu?das de microc?psulas de xilana
produzidas por reticula??o polim?rica interfacial foram revestidas por ES100 atrav?s de
secagem por aspers?o em diferentes propor??es polim?ricas e empregando-se NaOH 0,6N ou
tamp?o-fosfato pH 7,4, como solvente. As micropart?culas foram avaliadas quanto ao
rendimento, morfologia, granulometria, homogeneidade, aspecto visual, cristalinidade e
comportamento t?rmico. A intera??o entre os pol?meros foi investigada atrav?s da
espectroscopia na regi?o do infravermelho e de an?lises t?rmicas. A xilana extra?da
apresentou-se como um p? muito fino, com tamanho m?dio inferior a 40μm, e com colora??o
opaca levemente amarelada. A avalia??o das propriedades reol?gicas da xilana permitiram a
caracteriza??o desse pol?mero, em seu estado original de p?, como um material de baixa
densidade, fluxo restrito e bastante coesivo. Foram obtidas micropart?culas esf?ricas e sem
presen?a de agregados, com estrutura amorfa, em sua maior parte, e bastate est?veis a
temperaturas elevadas. Al?m disso, confirmou-se que a intera??o entre xilana e ES100 ocorre
apenas por agrega??o f?sica
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Size Separation Techniques for the Characterisation of Cross-Linked Casein: A Review of Methods and Their ApplicationsRaak, Norbert, Abbate, Raffaele Andrea, Lederer, Albena, Rohm, Harald, Jaros, Doris 11 June 2018 (has links)
Casein is the major protein fraction in milk, and its cross-linking has been a topic of scientific interest for many years. Enzymatic cross-linking has huge potential to modify relevant techno-functional properties of casein, whereas non-enzymatic cross-linking occurs naturally during the storage and processing of milk and dairy products. Two size separation techniques were applied for characterisation of these reactions: gel electrophoresis and size exclusion chromatography. This review summarises their separation principles and discusses the outcome of studies on cross-linked casein from the last ~20 years. Both methods, however, show limitations concerning separation range and are applied mainly under denaturing and reducing conditions. In contrast, field flow fractionation has a broad separation range and can be easily applied under native conditions. Although this method has become a powerful tool in polymer and nanoparticle analysis and was used in few studies on casein micelles, it has not yet been applied to investigate cross-linked casein. Finally, the principles and requirements for absolute molar mass determination are reviewed, which will be of increased interest in the future since suitable calibration substances for casein polymers are scarce.
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Polymer-silica Hybrids for Separation of CO2 and Catalysis of Organic ReactionsSilva Mojica, Ernesto 15 May 2014 (has links)
No description available.
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Investigations into High Surface Area and Hierarchical Phase Segregated Network StructuresViggiano, Rocco P., III January 2015 (has links)
No description available.
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Cellulose photonics : designing functionality and optical appearance of natural materialsGuidetti, Giulia January 2018 (has links)
Cellulose is the most abundant biopolymer on Earth as it is found in every plant cell wall; therefore, it represents one of the most promising natural resources for the fabrication of sustainable materials. In plants, cellulose is mainly used for structural integrity, however, some species organise cellulose in helicoidal nano-architectures generating strong iridescent colours. Recent research has shown that cellulose nanocrystals, CNCs, isolated from natural fibres, can spontaneously self-assemble into architectures that resemble the one producing colouration in plants. Therefore, CNCs are an ideal candidate for the development of new photonic materials that can find use to substitute conventional pigments, which are often harmful to humans and to the environment. However, various obstacles still prevent a widespread use of cellulose-based photonic structures. For instance, while the CNC films can display a wide range of colours, a precise control of the optical appearance is still difficult to achieve. The intrinsic low thermal stability and brittleness of cellulose-based films strongly limit their use as photonic pigments at the industrial scale. Moreover, it is challenging to integrate them into composites to obtain further functionality while preserving their optical response. In this thesis, I present a series of research contributions that make progress towards addressing these challenges. First, I use an external magnetic field to tune the CNC films scattering response. Then, I demonstrate how it is possible to tailor the optical appearance and the mechanical properties of the films as well as to enhance their functionality, by combining CNCs with other polymers. Finally, I study the thermal properties of CNC films to improve the retention of the helicoidal arrangement at high temperatures and to explore the potential use of this material in industrial fabrication processes, such as hot-melt extrusion.
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