To see the other types of publications on this topic, follow the link: Biomaterials.
Dissertations / Theses on the topic 'Biomaterials'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Biomaterials.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
FONTANA, FEDERICO. "Computational Approaches for biomaterials characterization and biomaterial-cell interactions." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2021. http://hdl.handle.net/10281/301794.
Full textAbstract:
I biomateriali per applicazioni di ingegneria dei tessuti devono soddisfare diversi requisiti, come sicurezza, biocompatibilità e caratteristiche meccaniche appropriate. Il processo di sviluppo di questi biomateriali comprende diversi approcci scientifici, che vanno dall' in-silico all'in-vivo. L'ottimizzazione in silico delle caratteristiche dei biomateriali sta attirando un'attenzione sempre maggiore. Infatti, il miglioramento di questo approccio consentirà di ridurre i costi aggiuntivi nel processo di sviluppo dei biomateriali, a causa di caratterizzazioni sperimentali non necessarie. Secondo questo punto di vista, in questa tesi viene presentato un approccio di dinamica molecolare per la caratterizzazione dei biomateriali. Più in dettaglio, gli scaffold degli idrogel di peptidi autoassemblanti (SAP) sono stati studiati su nanoscala e microscala, al fine di chiarire le loro relazioni intrinseche struttura-proprietà-funzione. Le dinamiche molecolari atomistiche a grana grossa (CG-MD) sono state utilizzate per studiare i meccanismi di auto-assemblamento che portano alla formazione di scaffold peptidici. A causa della mancanza di informazioni strutturali cruciali nelle simulazioni CG-MD, l'innovativa suite software, denominata Morphoscanner, è stata impiegata per la classificazione dei modelli di aggregazione conformazionale dei SAP. Quindi, le proprietà meccaniche e i meccanismi di rottura delle nanostrutture SAP sono stati studiati attraverso le simulazioni MD vincolate. Queste evidenze hanno portato allo sviluppo di un approccio CG-MD che mira a chiarire la complessa interazione tra membrane cellulari e nanofibrille SAP. In particolare, le simulazioni MARTINI CG-MD sono state utilizzate per comprendere gli effetti della nanofibrille peptidiche sulla dinamica dei domini lipidici nelle membrane neurali. Tali risultati aprono nuove dimensioni nel campo della biomateriomica, consentendo di comprendere ed eventualmente controllare i complessi fenomeni che influenzano le proprietà meccaniche e la biocompatibilità dei biomateriali a base peptidica per applicazioni di ingegneria tissutale.Biomaterials for tissue engineering applications have to comply with several requirements, such as safety, biocompatibility and appropriate mechanical features. The development process of these biomaterials encompasses several scientific approaches, ranging from in-silico to in-vivo. The in-silico optimization of biomaterials features is attracting even larger attention. Indeed, the improvement of this approach will allow to reduce additional costs int the biomaterials development process, due to unnecessary experimental characterizations. According to this point-of-view, in this thesis is presented a molecular dynamics approach for biomaterial characterization. More in details, self-assembling peptides (SAPs) hydrogels scaffolds have been investigated at the nano-scale and micro-scale, to elucidate their intrinsic structure-property-function relationships. The atomistic and coarse-grained molecular dynamics (CG-MD) have been used for the elucidation of self-assembling pathways of peptide-based scaffolds. Due to the lack of crucial structural information in CG-MD simulations, the innovative software suite, dubbed Morphoscanner, has been employed for the elucidation of conformational aggregation patterns of SAPs. Then, the mechanical properties and failure mechanisms of SAPs nanostructures have been investigated through the steered MD simulations. These evidences led the development of a CG-MD approach aiming to elucidate the complex interplay between cell membranes and SAPs nanofibrils. In particular, MARTINI CG-MD simulations have been used for understanding the effects of SAPS nanofibril on dynamics of lipid domains in neural membranes. Such achievements open up new dimensions in the field of biomateriomics, allowing to understand and eventually orchestrate the complex phenomena which affect the mechanical properties and biocompatibility of SAPs biomaterials for tissue engineering applications.
2
Carlsson, Louise. "Hierarchical Micro- and Nanostructured Superhydrophobic Surfaces to Reduce Fibrous Encapsulation of Pacemaker Leads : Nanotechnology in Practical Applications." Thesis, Linköpings universitet, Institutionen för fysik, kemi och biologi, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-71067.
Full textAbstract:
The purpose of this master’s thesis was to, by the use of nanotechnology, improve material properties of the biomedical polymer Optim™, used as the insulation of pacemaker leads. Improved material properties are required to reduce the extent of fibrous encapsulation of the leads. Today, laser ablation is used to be able to remove the pacemaker lead because of the fibrous tissue, which can cause the lead to adhere to vascular structures. Consequently, the laser ablation results in risks of damaging cardiovascular structures. Moreover, improved material properties are needed to reduce the friction at the surface and enhance the wear resistance. Large wearing occurs between the lead and the titanium pacemaker shell as well as lead against lead and the wearing can result in a damaged insulation, which in turn might result in removal of the device. To achieve these improved material properties a hierarchically micro- and nanostructured and superhydrophobic surface was fabricated and to enhance the wear resistance, nanocomposites with 1 wt % and 5 wt % added hydroxyapatite nanoparticles were fabricated. The surface structures were fabricated via hot embossing and plasma treatment and were characterised with atomic force microscopy, environment scanning electron microscopy and with contact angle measurements. To evaluate the biological response to the surfaces, adsorption of radioisotope labelled human serum albumin proteins and adhesion of the human fibroblast cell line MRC-5 were studied. The results show that a superhydrophobic surface, with contact angle as high as 170.0 ± 0.4 °, can be fabricated via hierarchically micro- and nanostructures on an Optim™ surface. The fabricated surface is more protein resistant and cell resistant compared to a smooth surface. The nanocomposites fabricated, especially the one with 5 wt % nanoparticles added, show an enhanced abrasive wear resistance compared to Optim™ without added nanoparticles. In conclusion, a hierarchically micro- and nanostructured superhydrophobic surface of the pacemaker lead seems promising for reducing the extent of fibrous encapsulation and by fabricating a nanocomposite, the abrasive wear damage of the lead insulation can be reduced.
3
Vásquez, Sancho Fabián. "Flexoelectricity in biomaterials." Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/643308.
Full textAbstract:
La flexoelectricidad es la capacidad de los materiales para generar electricidad al deformarse de forma no homogénea. Es una propiedad de todos los materiales y, en principio, posible que existiera en biomateriales. De hecho, ya se ha observado en estereocilios del oído interno, apuntando a su importancia para la transducción acústico-eléctrica en la audición de mamíferos. Esta tesis investiga las propiedades flexoeléctricas de varios compuestos biocerámicos, que van desde los huesos hasta el coral, poniendo énfasis no solo en medir las propiedades flexoeléctricas, sino también en relacionarlas con su papel fisiológico.
El Capítulo 1 introduce el tema de mecanoelectricidad de materiales y ofrece una visión general de los biomateriales estudiados en esta tesis.
En el Capítulo 2, se desarrolla un análisis teórico de las propiedades mecanoeléctricas de los sistemas no homogéneos. En biomateriales, la flexoelectricidad y piezoelectricidad no pueden separarse tan fácilmente como en el caso de las muestras cristalinas o cerámicas que son regulares y con propiedades definidas. Los biomateriales nos obligaron a considerar situaciones en las que la flexoelectricidad y piezoelectricidad pueden actuar a la vez. También, situaciones en las que la piezoelectricidad es capaz de disfrazarse como flexoelectricidad o viceversa, con el objetivo de establecer el marco conceptual para las mediciones y los resultados de los siguientes capítulos.
El Capítulo 3 describe y analiza las mediciones macroscópicas de flexoelectricidad en hidroxiapatita y huesos. La polarización inducida de ambos materiales arrojó resultados muy similares, lo que demuestra que la hidroxiapatita puede explicar la mayor parte de la polarización de los huesos sin necesidad de invocar la piezoelectricidad del colágeno.
Teniendo en cuenta que la flexoelectricidad es más relevante a la microescala, donde los gradientes de deformación son más grandes, el Capítulo 4 desarrolla un modelo para estudiar los campos flexoeléctricos en torno a las microgrietas en los huesos. La magnitud de los campos eléctricos generados por un crack puede inducir la apoptosis en los osteocitos que es el primer paso en el proceso de remodelación ósea.
En el Capítulo 5, realizamos experimentos in vitro con osteocitos y osteoblastos para determinar si los campos flexoeléctricos pueden afectar a las células. Observamos no solo que los campos flexoeléctricos generados por grietas pueden inducir apoptosis de células en el corto plazo, sino que, en los experimentos de cultivos a largo plazo, la flexoelectricidad también puede estimular la diferenciación de las células.
En el Capítulo 6, exploramos las propiedades mecanoeléctricas de otros biomateriales como los dientes, coral y el martillo de un camarón. Los dientes están compuestos por los mismos constituyentes que los huesos, y por lo tanto, es un buen material para comparar con el hueso. Mientras tanto, el coral es un material comúnmente utilizado como injerto óseo debido a las similitudes con el hueso. Al comparar las propiedades flexoeléctricas de ambos materiales, pudimos determinar que también son muy similares, lo que nos lleva a pensar que la compatibilidad flexoeléctrica puede ser un factor de ayuda en el buen desempeño de los injertos óseos coralinos, una posibilidad que proponemos explorar en otros candidatos para injertos óseos. Finalmente, el martillo de un camarón tiene una capacidad sobresaliente para soportar el estrés sin fracturarse y este fenómeno nos motivó a estudiar las propiedades mecanoeléctricas del martillo, ya que la flexoelectricidad afecta las propiedades mecánicas de la materia.
Finalmente, el Capítulo 7 brinda una descripción personal de las perspectivas y líneas futuras que podrían derivarse de esta investigación. La descripción completa de los procedimientos experimentales para experimentos electromecánicos y biológicos y el algoritmo de Mathematica que programé para calcular los campos flexoeléctricos alrededor de las grietas se encuentran en los apéndices.Flexoelectricity is the ability of materials to generate electricity upon being bent, or, more generally, upon being inhomogeneously deformed. It is a property that is allowed by symmetry in all materials and, therefore, it was in principle possible that it existed in biomaterials –one precedent existed for their observation in inner-ear stereocilia, in fact, pointing to its importance for acousto-electric transduction in mammalian hearing. In this context, this thesis investigates into the flexoelectrical properties of several biologically-produced ceramic composites, ranging from bones to coral, putting emphasis not only on measuring the flexoelectrical properties, but also in connecting them to their potential physiological role. Chapter 1 introduces the topic of the mechanoelectric properties of piezoelectricity and flexoelectricity, and gives an overview of the biomaterials studied in this thesis. In Chapter 2, a theoretical analysis of the mechanoelectric properties of inhomogeneous systems is developed. For biomaterials, flexoelectricity and piezoelectricity cannot be as easily separeted as in the case of crystal or ceramic samples that are regular and with defined properties. The use of biomaterials forced us to consider situations in which flexoelectricity and piezoelectricity may act together. Situations in which piezoelectricity is able to disguise itself as flexoelectricity or vice-versa are presented, with an aim to lay the conceptual framework for the electromechanical measurements and results of the following chapters. Chapter 3 describes the characterization and analysis of macroscopic measurements of flexoelectricity in hydroxyapatite and bones. Bending-induced polarization of both kinds of samples yielded very similar results, which demonstrates that hydroxyapatite can account for most of the polarization of bones without needing to invoke collagen piezoelectricity. Considering that flexoelectricity is more relevant at the microscale, where strain gradients are bigger, in Chapter 4, we developed a model to study flexoelectric fields around microcracks in bones. We determined that the magnitude of the electric fields generated by a loaded crack can induce apoptosis in osteocytes. Osteocyte apoptosys is known to be the first step in the bone remodeling process. In Chapter 5, we performed in vitro experiments with osteocytes and osteoblast to probe whether flexoelectric fields are indeed able to affect cells. We observed not only that crack-generated flexoelectric fields experiments are able to induce apoptosys of cells in the short term, but in the long-term culture experiments, flexoelectricity is also able to stimulate the differentiation of cells. Finally, in Chapter 6, we explored the mechanoelectric properties of other Ceramic-based biomaterials such as teeth, coral skeleton, and the club of a stomapod. In the case of teeth, they are composed by the same constituents as bones, and they were therefore a good material to compare with bone. Meanwhile, coral skeleton is a material commonly used as a bone graft due to the similarities with bone. By comparing flexoelectric properties of both materials, we were able to determine that they are also very similar, leading us to hypothesise that flexoelectric compatibility may be a helping factor in the good performance of coral-based bone grafts, a possibility we propose to explore in other candidates for bone grafts. Finally, the club of a stomapod has an outstanding capacity to stand stress without fracture and this phenomenon motivated us to study the mechanoelectric properties of the club, as flexoelectricity is known to affect the mechanical properties of matter. Finally, Chapter 7 gives a personal overview of the perspectives and future lines that could derive from this research. The complete description of experimental procedures for electromechanical and biological experiments is in Appendix ), and Appendix B is the Mathematica algorithm that I programmed for calculating flexoelectric fields around cracks.
4
Richter, Maja. "Study of immune and haemostatic response induced by protein multilayers." Thesis, Linköpings universitet, Tillämpad Fysik, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-62304.
Full textAbstract:
FibMat2.0 is a fibrinogen multilayer developed by AddBIO. Other proteins such as immunoglobulin G (IgG) and human serum albumin (HSA) can also be used to build multilayers with the same technique. The aim of this study of FibMat2.0 was to investigate if the manufacturing of the protein multilayer would induce an immune or haemostatic response in the body. The multilayers of IgG and HSA were also studied. Methods such as null ellipsometry, imaging of coagulation and the cone-and-plate setup were used to study immune reactions, activation of the coagulation cascade, and stability of the multilayers. Small amounts of plasma proteins were adsorbed to fibrinogen multilayers, but complement proteins adsorbed only to the IgG matrix and high molecular weight kininogen (HMWK) adsorbed only to the HSA monolayer. The imaging of coagulation method indicated that the titanium surface and the HSA monolayer activate surface induced coagulation rapidly, whereas fibrinogen and IgG multilayers demonstrated longer coagulation times. Platelets and a few white blood cells were bound to titanium surfaces and fibrinogen multilayers, but not to IgG multilayers or HSA monolayers. A conclusion in this study is that the surface of an implant can be coated with FibMat2.0 without any risks, but more studies are needed to better understand the interactions between the surfaces prepared in the present study and the immune and the haemostatic systems of the human body.
5
Matl, Florian. "Infected Biomaterials." Diss., lmu, 2008. http://nbn-resolving.de/urn:nbn:de:bvb:19-95998.
Full text
6
Jansson, Eva. "Blood protein coated model biomaterials : preparation, and cell and tissue response /." Linköping : Univ, 2003. http://www.bibl.liu.se/liupubl/disp/disp2003/tek798s.pdf.
Full text
7
Karlsson, Linda. "Biomolecular interactions with porous silicon /." Linköping : Univ, 2003. http://www.bibl.liu.se/liupubl/disp/disp2003/tek804s.pdf.
Full text
8
McGoldrick, Niamh. "Light triggered biomaterials." Thesis, Queen's University Belfast, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.579751.
Full textAbstract:
Implantable devices such as urethral catheters are the most commonly used urological devices. The most common problem affecting these devices is infection, leading to significant morbidity and eventual mortality. The challenge is to alleviate the long-term issue of device related infection. This study involved the development of light-responsive biomaterials, which demonstrated the controlled release of model therapeutic agents from within the polymer matrix, when irradiated with a specific wavelength of light. The use of light as a trigger for the release of a therapeutic agent from a polymeric matrix is attractive, as wavelength, intensity, site and duration of application of light can be coupled to release of the therapeutic agent. The pphotolabile ester of3,5-dimethoxybenzoin with a model acidic drug (ibuprofen) attached was synthesised and loaded into the polymer scaffold, which comprised of2-(hydroxyethyl) methacrylate crosslinked with ethyleneglycol dimethacrylate, once irradiated, the porous hydrogel allowed the diffusion of the model drug from the polymer matrix once liberated, and the retention of the photolytic by-product within the polymer structure. A second 3,5-dimethoxybenzoin ester was synthesised with ciprofloxacin attached, achieving controlled release of an antimicrobial in situ, thus preventing bacterial adherence and subsequent biofilm formation. The idea of chromatic orthogonality was explored and the 3,5-dimethoxybenzoin and nitrobenzyl derivatives were synthesised and utilised due to their differential reactivities at specific wavelengths, allowing multi-drug release, stimulated using monochromic light of different wavelengths. Light triggered transdermal drug delivery was examined,. novel pHEMA microneedles with the light reactive conjugate incorporated into the matrix were successfully synthesised. Drug release studies demonstrated the ability of the pHEMA microneedles to penetrate the synthetic skin and deliver the model drug ibuprofen. Modification of the surface ofa silicone biomaterial to allow the incorporation of two different porphyrins Meso- Tetraphenylporphyrin and Protoporphyrin IX was carried out, in order to develop an anti-adherent surface, preventing attachment of microorganisms and subsequent biofilm formation. An anti-infective surface has been developed which is successful at preventing bacterial colonisation of Gram-positive microorganism. The concept of light-triggered drug release of a model therapeutic agent from a hydrogel biomaterial has been demonstrated, it offers an exciting new prospect within drug delivery.
9
McCullagh, S. D. "Novel silicone biomaterials." Thesis, Queen's University Belfast, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273237.
Full text
10
Engberg, Anna E. "Biomaterials and Hemocompatibility." Doctoral thesis, Linnéuniversitetet, Institutionen för naturvetenskap, NV, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-5437.
Full textAbstract:
Biomaterials are commonly used in the medical clinic today; however, artificial materials can activate the cascade systems in the blood (complement-, coagulation-, contact- and fibrinolytic systems) as well as the platelets to various degrees. When an artificial surface comes in contact with blood, plasma proteins will be adsorbed to the surface within seconds. The composition of the layer of proteins differs between materials and is crucial for the hemocompatibility of the material. This thesis includes five projects. In Paper I the anticoagulants heparin and the thrombin inhibitor hirudin were evaluated in a whole blood model. Hirudin was found to be superior to low dose heparin since it did not affect the activation of the complement system nor the leukocytes. The most interesting observation was that expression of TF was seen on surface-attached monocytes in hirudin- treated blood but not heparin blood. In Paper II peptides from the streptococcal M-protein, which has affinity for the human complement inhibitor C4BP, were attached to a polymeric surface. When being exposed to blood the endogenous complement regulator was enriched at the surface of the material, via the M-peptides. With this new approach we created a self-regulatory surface, showing significant lowered material-induced complement activation. In Paper III apyrase, an enzyme which hydrolyzes nucleoside ATP and ADP, was immobilized on a polymer surface. Lower platelet activation and platelet-induced coagulation activation was seen for the apyrase-coated surface compared to control surfaces after exposure to whole human blood, due to the enzymes capability to degrade ADP released from activated platelets. In Paper IV and V we synthesized an array of polymeric materials which were characterized regarding physical-chemical properties, adsorption of plasma proteins, and hemocompatibility. The polymers showed widely heterogeneous protein adsorption. Furthermore, when the polymers were exposed to whole blood, two of the materials showed superior hemocompatibility (monitored as complement- and coagulation activation), compared to the reference poly(vinyl chloride).
11
Lemes, Ana Paula. "Desenvolvimento de novos compositos biodegradaveis baseados em poli (3-hidroxibutirato-co-hidroxivalerato) e lignosulfonatos." [s.n.], 2005. http://repositorio.unicamp.br/jspui/handle/REPOSIP/248905.
Full textAbstract:
Orientador: Nelson Eduardo Duran CaballeroDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica
Made available in DSpace on 2018-08-05T10:26:59Z (GMT). No. of bitstreams: 1 Lemes_AnaPaula_M.pdf: 6068307 bytes, checksum: cde69555a9767e84a264aae77c5a0814 (MD5) Previous issue date: 2005
Resumo: Neste trabalho foram desenvolvidos compósitos baseados em poli(3-hidroxibutirato-co-hidroxivalerato) (PHBV) e lignosulfonatos de diferentes massas molares. Os compósitos foram produzidos em um misturador mecânico, em diferentes composições (90:10, 80:20, 70:30 e 60:40). As propriedades térmicas dos compósitos foram investigadas por Calorimetria Diferencial de Varredura (DSC) e Termogravimetria (TGA). As análises de Microscopia Eletrônica de Varredura foram utilizadas para caracterizar a morfologia dos materiais. Os compósitos com maiores proporções de lignosulfonatos apresentaram diminuição no grau de cristalinidade e na temperatura de transição vítrea e menor estabilidade térmica. As análises de MEV mostraram uma baixa adesão interfacial entre os lignosulfonatos e a matriz de PHBV. Para promover uma melhor adesão interfacial entre a carga e a matriz, foi realizado um estudo utilizando um agente compatibilizante, que consistia na exertia de anidrido maleico (AM) na cadeia de PHBV (PHBV-g-AM). Para isto compósitos contendo 80 % de PHBV e 20 % de lignosulfonatos e proporções variadas de anidrido maleico foram produzidos em um misturador mecânico e em uma extrusora dupla rosca. Esses compósitos foram caracterizados por TGA e MEV. Na análise de TGA não foram observadas grandes alterações na estabilidade térmica. As análises morfológicas mostraram uma grande melhora na adesão entre carga e matriz. Os compósitos compatibilizados apresentaram um aumento de cerca de 125 % nos valores de tensão de flexão máxima e de 145 % nos valores de deformação na ruptura, em relação aos compósitos não compatibilizados. Amostras de PHBV e do compósito contendo 80 % de PHBV, 20 % de lignosulfonato e 1,5 % de anidrido maleico foram submetidas a testes de biodegradação em meio líquido e em solo. Os testes realizados em meio líquido mostraram uma redução de massa de 14,4 % para as amostras de PHBV e de 31,0 % para o compósito, após 65 dias de incubação. Nos testes realizados em solo a perda de massa foi de 7,6 % para as amostras de PHBV e 28,8 % para o compósito, após 50 dias de incubação. A perda de 20 % em massa dos compósitos foi atribuida à liberação de lignosulfonato. Em ambos os testes verificou-se que a presença do lignosulfonato não interfere na biodegradação da matriz de PHBV
Abstract: In this work, composites based on poly(3-hydroxybutyrate-co-hydroxyvalerate) (PHBV) and lignosulfonates of different molar weights were prepared by mechanical mixing of different compositions (90:10, 80:20, 70:30 and 60:40). Thermal properties of these composites were investigated by differential scanning calorimetric (DSC) and thermogravimetric analysis (TGA). Scanning electron microscopy (SEM) was used to define the morphology of materials. The composites containing higher amounts of lignosulfonates showed a decreasing in crystallinity degree and glass transition temperatures, and lower thermal stability. SEM showed a poor interfacial adhesion between lignosulfonato and PHBV matrix. To improve the interfacial adhesion between filler and matrix, a study on compatibilizer utilization was carried out. The compatibilizer was formed by grafting of maleic anhydride (MA) in PHBV (PHBV-g-MA). The study was performed with composites containing 20 % of lignosulfonate, 80 % of PHBV and different amounts of maleic anhydride, prepared by mechanical mixing and by twin-screw. The thermal and morphological properties of composites were investigated by TGA and SEM, respectively. The TGA did not show significant change in the thermal stability of the composites as function of compatibilizer content. The SEM showed a high improvement in the adhesion between filler and matrix. The compatibilized composites exhibited an increase of 125 % in maximum stress values and 145 % in the strain values under rupture experiments. PHBV and composite containing 80 % of PHBV, 20 % of lignosulfonato and 1,5 % of maleic anhydride samples were submitted to biodegradation tests in aqueous and in soil media. Tests carried out in aqueous medium showed a decrease of 14, 4 % in the PHBV mass and 31,0 % in the composite mass, after 65 days of incubation. In the soil tests the weight loss was of 7,6 % for PHBV sample and 28,8 % for composite sample, after 50 days of incubation. Both tests showed that the presence of lignosulfonate did not interfere in PHBV matrix biodegradation
Mestrado
Físico-Química
Mestre em Química
12
Strasser, Stefan. "Nanotechnological Characterisation of Biomaterials." Diss., lmu, 2007. http://nbn-resolving.de/urn:nbn:de:bvb:19-78763.
Full text
13
Casadio, Ylenia Silvia. "Biodegradable PHEMA-based biomaterials." University of Western Australia. School of Biomedical, Biomolecular and Chemical Sciences, 2009. http://theses.library.uwa.edu.au/adt-WU2009.0173.
Full textAbstract:
[Truncated abstract] The synthetic hydrogel poly(2-hydroxyethyl methacrylate) (PHEMA) has been used as a biocompatible biomaterial in ocular devices, such as soft contact lenses, intraocular lenses and an artificial cornea. Due to its favourable properties as an already established (but non-biodegradable) biomaterial, PHEMA is an interesting candidate for use as a material for scaffolds in tissue engineering. A tenant of tissue engineering scaffolds is obtaining the appropriate porous morphology to allow for successful cellular attachment and support. PHEMA hydrogels exhibit varied morphological features, which range from non-porous (homogeneous) to macroporous (heterogeneous) and can be readily obtained by fine-tuning the polymerisation conditions. A desirable feature for matrices that are to be used as tissue supports is the ability to biodegrade in a biological environment. This thesis describes the preparation and enzymatic biodegradation behaviour of novel porous PHEMA hydrogels that have been crosslinked with biodegradable peptide-based crosslinking agents. Peptide-based crosslinking agents were designed to contain two terminal polymerisable groups flanking an internal biodegradable backbone. This backbone was specifically designed to be targeted by the proteolytic enzyme papain. The general design template allowed for the development of a synthetic methodology that was readily implemented for the production of a range of olefin-peptide conjugates. A suite of olefin-peptide conjugates of general structure I were synthesised, characterised and further tested with papain to determine their biodegradation properties. ... The second strategy for producing bioresorbable degradation fragments involved the incorporation of the highly hydrophilic comonomer, poly(ethylene glycol) PEG into the PHEMA backbone. The addition of PEG to PHEMA resulted in the formation of homogeneous hydrogels that had an improved hydrophilicity compared to their heterogeneous PHEMA counterparts. The synthetic conditions for the preparation of PHEMA and PHEMA-co-PEG hydrogels by photoinitiated polymerisation were thoroughly investigated. It was found that the pore morphology and general properties (non-porous to macroporous) of these hydrogels could be controlled by the appropriate choice of polymerisation conditions. The hydrogels were characterised by scanning electron microscopy, thermal gravimetric analysis and differential scanning calorimetry. The peptide-based crosslinking agents were successfully co-polymerised with the HEMA and PEGMA via photoinitiated polymerisation to provide a range of PHEMA and PHEMA-co-PEG hydrogels that displayed both homogeneous and heterogeneous hydrogel properties. The final crosslinked hydrogels were characterised by scanning electron microscopy and were subjected to enzymatic hydrolysis. The PHEMA-peptide conjugate hydrogels proved to be biodegradable, with degradation behaviour dependent on the hydrogel formulation and the length of the peptide-based crosslinking agent.
14
Irwin, Nicola Jayne. "Infection-responsive urinary biomaterials." Thesis, Queen's University Belfast, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.602549.
Full textAbstract:
The catheterised urinary tract constitutes an ideal niche for bacterial colonisation, with an estimated 80% of all nosocomial urinary infections attributed to the presence of an indwelling catheter. The present thesis describes the rational design and development of three novel drug delivery systems for application as infection-resistant catheter coatings, which respond to the alkaline conditions generated at the onset of urinary catheter infections by urease-producing pathogens, particularly Proteus mirabilis, via the release of drugs. Upon probing P. mirabilis biofilms with a pH microelectrode, values up to pH 10.12 were recorded directly within the biofilm micro environment. In addition to exploiting this pH elevation to act as a trigger for drug release, the effect of pH on quinolone antibacterial activity is reported herein. Specifically, bactericidal potency of the fluoroquinolone agents: norfloxacin and ciprofloxacin, against P. mirabilis was observed to increase with elevated pH, whereas high concentrations of nalidixic acid demonstrated bactericidal activity selectively in alkaline environments, in contrast to the characteristic 'paradoxical' survival of bacteria observed with high concentrations of this agent in acidic and neutral media. In the first drug delivery system developed herein, the inherent pH -dependent physicochemical properties of nalidixic acid were exploited by a novel, surface particulate localisation method to achieve up to 50-fold faster drug release at pH 9 , than at normal physiological urine pH values ranging from pH 5 to pH 7. In contrast to physical drug loading, the final two systems focused on chemical conjugation of nalidixic acid and surfactant moieties via labile ester bonds to hydrogel backbones. Release of the covalently attached agents was successfully delayed at pH 7 compared to the significantly faster rates of ester hydrolysis and subsequent release at pH 10. Comparative differences in the resistances to bacterial adherence relative to the control hydrogel were demonstrated depending on the specific conjugated agent.
15
Albustany, Kamal Rashed. "Bone response to biomaterials." Thesis, University of Liverpool, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.261974.
Full text
16
Rosengren, Agneta. "Tissue reactions to biomaterials." Lund : Dept. of Physiology and Neuroscience, Section for Neuroendocrine Cell Biology, and the Dept. of Experimental Research, University Hospital MAS, Lund University, 1997. http://catalog.hathitrust.org/api/volumes/oclc/38986628.html.
Full text
17
RUSSO, LAURA. "design of smart biomaterials." Doctoral thesis, Università degli Studi di Milano-Bicocca, 2012. http://hdl.handle.net/10281/28929.
Full textAbstract:
The general aim of the project is the development of innovative materials for bone and cartilage tissue engineering, focusing on the design of smart biomimetic materials, fully integrating principles from cell and molecular biology able to directly regulate cell differentiation and metabolism. Materials equipped with molecular cues mimicking the structure or function of natural extracellular microenvironments are able to interact with surrounding tissues by biomolecular recognition (Lutolf, MP 2005). Biomimetic materials should be capable of eliciting specific cellular responses and directing new tissue formation mediated by specific interactions, which can be manipulated by altering design parameters.
Smart materials should provide the opportunity for chemically linking biological signalling molecules such as peptides or small proteins, or carbohydrates, eliciting cell responses to help the healing process.
For tissue repair, biomaterials should have several properties to support viable repair. Firstly, the material must act as a support structure for cells and possess enough mechanical strength to protect the cells contained within it. Secondly, some level of bioactivity should be provided to accommodate cellular attachment and migration. Furthermore, the materials should be biodegradable and remodel as the new tissue forms and replaces the original construct. In this regard, the matrix should be non-toxic, non-attractive and non-stimulatory of inflammatory cells, and also non-immunogenic, which would be detrimental to tissue regeneration. Finally, the scaffolds should provide easy handling under clinical conditions, enabling fixation of the materials into the implant site [Stoop R. 2008].
In the present work, we are studying and applying functionalization strategies of different materials with signaling biomolecules. New smart materials were designed and synthetized to obtain innovative scaffolds useful in forming tissues with oriented mechanical and cellular properties. At the same time, functionalized materials with various biochemical signals will influence MSCs behaviour in vitro enhancing the differentiation in chondrogenic and osteogenic line cells and the matrix production and remodeling.
18
Cunha, Marcelo Rodrigues da. "Implantes tridimensionais de colageno polianionico em falhas osseas produzidas no femur de ratas ovariectomizadas." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/317943.
Full textAbstract:
Orientadores: Selma Candelaria Genari, Arnaldo Rodrigues dos Santos JuniorTese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
Made available in DSpace on 2018-08-07T07:23:28Z (GMT). No. of bitstreams: 1 Cunha_MarceloRodriguesda_D.pdf: 5098178 bytes, checksum: b94b973afe0b096e483ba907231c9237 (MD5) Previous issue date: 2006
Resumo: Recentemente, existe um interesse no desenvolvimento de biomateriais que possam ser utilizados na substituição do tecido ósseo ou que atuem como indutores na reparação em caso de fraturas ou defeitos ósseos. Os biomateriais constituídos de elementos de matriz extracelular tridimensionais (MECa) compostas de colágeno/elastina apresentam a vantagem de poder sofrer alterações nas suas propriedades por modificações químicas do colágeno, resultando em matrizes carregadas positivo ou negativamente. Tais modificações podem melhorar as propriedades mecânicas e fisiológicas da MECa. O objetivo deste trabalho foi avaliar a capacidade das MECa de colágeno nativo e polianiônica no processo de reparação de defeitos produzidos no fêmur de ratas ovariectomizadas. Foram realizados defeitos na porção do côndilo femoral de ratas normais e ovariectomizadas. Foi feita a análise das características morfológicas, físicas e mecânicas do osso formado na região. A análise do material demonstrou ausência de alterações patológicas nas áreas implantadas, sugerindo que o material usado é biocompatível. A análise microscópica revelou que a área que recebeu a membrana de colágeno nativa teve menor quantidade de osso neoformado. Nos animais ovariectomizados que receberam membranas polianiônicas, observou-se um atraso no processo da regeneração na falha óssea, principalmente naqueles que não foram submetidos à reposição hormonal. A densidade e percentual mineral foi menor nos animais ovariectomizados e a resistência mecânica foi maior nas áreas que receberam membrana polianiônica 96 (PMC96). Conclui-se que nos casos de osteoporose por deficiência hormonal, a melhor membrana a ser utilizada num reparo ósseo é a polianiônica 96, pois proporciona crescimento ósseo mais rápido e de boa qualidade mecânica
Abstract: There has been recent interest in the development of biomaterials that can be used as replacement of bone tissue or that act as inducer of the healing process in the case of bone fractures or defects. Biomaterials consisting of three-dimensional extracellular matrix elements (aECM) composed of collagen/elastin have the advantage that their properties can be altered by introducing chemical modifications to the collagen that result in positively or negatively charged matrices. These modifications may improve the mechanical and physiological properties of aECM. The objective of the present study was to evaluate the effect of aECM consisting of native and polyanionic collagen on the healing process of defects created in the femur of ovariectomized rats. Defects were created in the femoral condyle of intacts and ovariectomized rats and the morphological, physical and mechanical characteristics of the bone formed in the region were analyzed. The results showed the absence of pathological alterations on implanted areas, suggesting that the implants were biocompatible. Microscopic analysis verified that areas that received native membrane had less quantity of neoformed bone. In ovariectomized animals that received anionic membranes, we observed a delay in bone regeneration, mainly in animals that did not receive hormonal replacement. The density and mineral matter percentage was smaller in ovariectomized animals and the a mechanical resistance was greater in the area receiving the 96 polyanionic membrane (PMC96). Thus, we conclude that in cases of osteoporosis due to hormone deficiency, the 96 polyanionic membrane possibly is the best to be used for bone repair since it provides faster bone growth, as well as good mechanical resistance
Doutorado
Anatomia
Doutor em Biologia Celular e Estrutural
19
Rodriguez, Chessa Jaime Giuseppe. "Estudo comparativo da resistencia mecanica a flexão de placas e parafusos reabsorviveis e metalicos utilizados em osteotomias de corpo em mandibulas de poliuretano." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288690.
Full textAbstract:
Orientador: Renato MazzonettoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-12T05:52:39Z (GMT). No. of bitstreams: 1 RodriguezChessa_JaimeGiuseppe_M.pdf: 1416977 bytes, checksum: 2b782ab4c409f0bfb1fc8e34d43c205b (MD5) Previous issue date: 2008
Resumo: O propósito deste trabalho foi avaliar e comparar a resistência mecânica à flexão de placas e parafusos metálicos e reabsorvíveis para fixação interna rígida. Foram utilizadas hemimandíbulas sintéticas de poliuretano, nas quais se realizou uma osteotomia entre o segundo pré-molar e o primeiro molar inferior, simulando uma fratura de corpo mandibular. Foram estabelecidos dois grupos para placas e parafusos metálicos e dois grupos para reabsorvíveis de acordo com a seguinte disposição: duas placas metálicas mantidas com parafusos monocorticais de 6 mm na zona de tensão e outra com parafusos bicorticais de 12 mm de comprimento na zona de compressão. Após a fixação rígida, foi realizado o teste de resistência à flexão em máquina de ensaio universal (Instron®, modelo 4411) programada com velocidade de deslocamento linear de 1 mm/min e com célula de carga de 500N para obtenção do valor da resistência à flexão em quilograma-força com incidência de carga em região de incisivo e pré-molar em cada um dos grupos estudados. Os resultados demonstraram não existir diferença estatisticamente significante entre os sistemas de fixação interna rígida de titânio e reabsorvível, quando avaliadas as variáveis deslocamento (em mm) e a carga de pico (em kgf) para os 4 grupos amostrais.
Abstract: The meaning of this study was to evaluate and compare the resistance to flexion between metallic and absorbable plates and screws for rigid internal fixation. It was used synthetic hemimandible of polyurethane, in which one was performed a straight cut between second premolar and first molar, simulating a breaking of mandibular body. It was established two groups for metallic plates and screws and two groups for absorbable according to following disposal: two metallic plates kept with 6mm monocortical screws in the tension zone and another one with 12mm bicortical screws in the compression zone. After the rigid fixation, it was carried out the flexion resistance test thru a universal assay machine (Instron®, model 4411) performed with 1mm/minute linear displacement speeding with 500N of bearing cell for attainment the flexion resistance value in kilogram-force with the load incidence in the incisor and premolar regions on each group studied. The results had demonstrated to not exist statistical significant difference between the titanium and absorbable systems, when evaluated the variable displacement (in mm) and the peak load (in kgf) for the 4 groups tested.
Mestrado
Cirurgia e Traumatologia Buco-Maxilo-Faciais
Mestre em Clínica Odontológica
20
Chaves, Netto Henrique Duque de Miranda. "Avaliação do carreador carboxi-metil-celulose associado a matriz ossea bovina anorganica em defeitos na calota de cães : analise histologica e radiologica." [s.n.], 2009. http://repositorio.unicamp.br/jspui/handle/REPOSIP/288686.
Full textAbstract:
Orientador: Renato MazzonettoDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-13T00:13:29Z (GMT). No. of bitstreams: 1 ChavesNetto_HenriqueDuquedeMiranda_M.pdf: 50043298 bytes, checksum: 5e69f8521d79914d88a950613cc0569c (MD5) Previous issue date: 2009
Resumo: Os procedimentos cirúrgicos envolvendo a reabilitação da região maxilofacial freqüentemente requerem o uso de enxertos ósseos para a reconstrução de deformidades congênitas ou adquiridas, assim como para correções esqueléticas com finalidade estética. Com o objetivo de evitar a abordagem de áreas doadoras para obtenção de enxerto ósseo, os substitutos ósseos foram desenvolvidos. Visando minimizar a dificuldade de adaptação dos substitutos ósseos na área doadora, os veículos para inserção destes vêm sendo estudados. Para o presente estudo, foram utilizados 8 cães, machos, sem distinção de raça, provenientes do biotério da Unicamp. Após tricotomia e anti-sepsia com polivinilpirrolidona iodo a 10% foram realizados 4 defeitos bicorticais de 8mm de diâmetro na calota craniana de cada animal. O preenchimento das cavidades se deu do seguinte modo: Grupo I - coágulo sangüíneo, Grupo II - osso autógeno particulado, Grupo III - matriz óssea bovina anorgânica, Grupo IV - matriz óssea bovina anorgânica associada a carboxi-metilcelulose. Os períodos de sacrifício foram de 3 e 6 semanas. Através de análise descritiva radiológica e histológica, observou-se no período de 3 semanas a presença de tecido conjuntivo, vasos sangüíneos, material utilizado para preenchimento, assim como as bordas nítidas em todos defeitos. O Grupo II foi o único a apresentar regiões de aposição de novo tecido ósseo. No período de 6 semanas observou-se a presença de tecido conjuntivo, vasos sangüíneos e material utilizado para preenchimento em todos defeitos. O Grupo II foi o único que apresentou as partículas de osso autógeno utilizadas para o preenchimento em estágio de reabsorção avançado sendo também o único a não apresentar as bordas entre o defeito e osso pré-existente nítidas, no período de 6 semanas. Desta forma observou-se que, apesar do enxerto de osso autógeno apresentar melhores resultados em termos de reparação óssea, a matriz óssea bovina anorgânica demonstrou ser biocompatível, servindo como osteocondutor, assim como que o carreador carboxi-metil-celulose influênciou de maneira negativa o processo de reparação óssea.
Abstract: Surgical procedures involving maxillofacial region frequently require bone grafting to reconstruct the congenital or acquired defects, as well to aesthetic. Meaning to avoid the donate areas to obtain grafts, the biomaterials have been developed, especially to minimize the hardiness adaptation of them. This way, several vehicles to insert of these bone substitutes are been studied. To perform the present studied were used 8 dogs, males, without pedigree, from the Unicamp vivarium. After trichotomy and antisepsis with PVPI 10% were performed 4 bicortical defects having 8mm of diameter on the calvarium of each animal. The cavities were filled up thru the following way: Group I - Blood clot, Group II - particulate autogenous bone graft, Group III - anorganic bovine bone matrix, Group IV - anorganic bovine bone matrix associated with a carboxi-metil-celulosis. The sacrifice periods were 3 and 6 weeks. Thru the descriptive radiologic and histological analysis, it was observed on 3 weeks period, presence of connective tissue, blood vessels, material used for fulfillment, as well as periphery of the defects well delimited. The Group II was the only one that presented new bone aposition. On the 6 weeks sacrifice period, it was noted the presence of connective tissue, blood vessels, material used for fulfillment in all defects. The Group II was the only one that showed advanced resorption stage of the bone grafts particles used for fulfillment being, also the only one that showed periphery of the defects without limit, on the 6 weeks period. The present work demonstrated that, despite the autogenous bone grafts lead to the best result in terms of bone defect repair, the anorganic bovine bone matrix demonstrated to be biocompatible, being osteoconductible, as well the carrier carboximetil- celulosis interfered negatively on the bone repair process.
Mestrado
Cirurgia e Traumatologia Buco-Maxilo-Faciais
Mestre em Clínica Odontológica
21
Moraes, Mariana Agostini de 1985. "Obtenção e caracterização de blendas e compósitos poliméricos de fibroína de seda e alginato de sódio." [s.n.], 2010. http://repositorio.unicamp.br/jspui/handle/REPOSIP/266963.
Full textAbstract:
Orientador: Marisa Masumi BeppuDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química
Made available in DSpace on 2018-08-16T01:55:24Z (GMT). No. of bitstreams: 1 Moraes_MarianaAgostinide_M.pdf: 6610983 bytes, checksum: 6a0bd18a488acc990acac9560237163b (MD5) Previous issue date: 2010
Resumo: A utilização de polímeros de fontes renováveis vem sendo amplamente estudada tanto no campo biomédico quanto nas indústrias de embalagens. Polímeros naturais são, em geral, biodegradáveis, biocompatíveis e podem ser obtidos a custos relativamente baixos. Biopolímeros como o alginato de sódio e a fibroína de seda vêm se destacando como potenciais matériasprimas para a fabricação de membranas e de biomateriais. O objetivo deste trabalho foi explorar a possibilidade de se formar membranas de fibroína de seda com alginato de sódio, a fim de conjugar as propriedades desses biopolímeros, visando possíveis aplicações como biomaterial. Foi estudada a incorporação da fibroína no alginato de sódio sob diferentes formas, como a incorporação na forma de fios (para a obtenção de compósitos) e como solução (para a obtenção de blendas). Na obtenção da blenda de fibroína e alginato foi observada a formação de uma membrana composta majoritariamente de alginato, contendo glóbulos de fibroína, indicando separação microscópica de fases. Entretanto ocorreu interação entre os domínios hidrofílicos dos dois materiais, fato confirmado pelo DRX. A blenda apresentou espectro de FTIR similar ao do alginato, porém com picos característicos de conformação folha-b da fibroína. Para as análises de intumescimento em água, ângulo de contato, permeabilidade ao vapor d'água, resistência à tração, análises térmicas e citotoxicidade, a blenda apresentou comportamento intermediário entre seus componentes, contudo mais voltado para o alginato, presente em maior proporção na mesma. Através da formação da blenda com alginato de sódio foi possível melhorar as propriedades físicas da membrana quando comparadas com a membrana de fibroína pura. Com a incorporação dos fios de fibroína no alginato obteve-se um compósito com boa interação fibramatriz, observada pelos testes mecânicos e MEV. Os compósitos eram bastante maleáveis e apresentavam elevada resistência ao rasgo. As análises térmicas apresentaram picos de degradação dos dois componentes separadamente. Nenhuma das membranas obtidas neste trabalho apresentou citotoxicidade, sendo a viabilidade celular mantida entre 70 e 100%. Os materiais resultantes possuem potencial para serem explorados como biomateriais, entretanto testes específicos de utilização devem ser realizados.
Abstract: The use of polymers from renewable sources has been widely studied in the biomedical field as much as in the packaging industries. Natural polymers are, in general, biodegradable, biocompatible and can be obtained at low costs. Biopolymers such as sodium alginate and silk fibroin are potential raw-materials for production of membranes and biomaterials. The aim of this study was to explore the possibilities of forming membranes of silk fibroin with sodium alginate, in order to conjugate the properties of those biopolymers, for biomaterial applications. The incorporation of fibroin in sodium alginate under different forms was studied, such as the incorporation of silk as fibers (to obtain composites) or as solution (to obtain blends). The fibroin and alginate blend membrane was mainly composed by alginate, with fibroin globular domains, indicating micro-phase separation. However, interaction in the hydrophilic domains of the materials has occurred, confirmed by XRD. The blend presented FTIR spectrum similar to alginate, but with characteristic peaks of fibroin b-sheet conformation. For the degree of swelling in water, water contact angle, water vapor permeability, tensile strength, thermal analyses and cytotoxicity tests, the blend presented intermediate behavior between its components, however closer to alginate, which was present in higher proportion. Through the blend formation with sodium alginate, it was possible to improve the physical properties of the fibroin membrane. A composite with good fiber-matrix interaction was obtained through the incorporation of fibroin fibers in the alginate matrix. This fact was confirmed by mechanical tests and SEM. These composites were flexible and presented high resistance to tear. The thermal analyses presented degradation peaks of the two components, separately. None of the membranes prepared in this study presented cytotoxicity and the cellular viability was maintained between 70 and 100%. The materials present high potential to be explored as biomaterials, therefore specific tests are still necessary.
Mestrado
Engenharia de Processos
Mestre em Engenharia Química
22
Pepino, Rebeka de Oliveira. "Desenvolvimento de géis e esponjas de quitosana e blendas quitosana/gelatina em ácido adípico." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/75/75135/tde-19042016-162109/.
Full textAbstract:
A quitosana é um biopolímero estudado em diversas áreas, tais como, ambiental, alimentícia, farmacêutica, biomédica e biotecnológica. Ela pode ser obtida de diferentes formas polimórficas de quitina, dentre as quais a forma β tem se mostrado vantajosa, pois favorece modificações químicas mais homogêneas e leva a um produto final menos alergênico. A quitosana pode ser combinada com outros compostos a fim de interagir e/ou reagir com eles e modificar suas propriedades. O objetivo deste trabalho foi estudar como uso de ácido adípico, em substituição ao acético, afeta as propriedades de géis e esponjas de quitosana e de quitosana/gelatina, que foram posteriormente reticuladas com os agentes reticulantes EDC/NHS. As técnicas utilizadas para os estudos foram: reologia, FTIR, MEV, absorção em PBS e ensaios de citotoxicidade. Por reologia, observou-se que o aumento na concentração dos géis de quitosana tornou os géis mais elásticos e viscosos. O mesmo ocorreu na presença de gelatina ou EDC/NHS. O efeito do uso de ácido adípico em substituição ao acético também foi mostrado nos ensaios reológicos, pois os géis com 2% de quitosana e com quitosana/gelatina sem EDC/NHS se mostraram mais elásticos e mais viscosos quando o ácido adípico foi usado. Os espectros FTIR mostraram a presença de interações entre a quitosana e a gelatina e a formação de ligações amidas II após reticulação com EDC/NHS. Na preparação das esponjas observou-se que os géis de quitosana em ácido adípico geravam esponjas instáveis que se desfizeram durante a neutralização, mas essa instabilidade não ocorreu com a blenda. As esponjas preparadas com a blenda foram estudadas após neutralização e o MEV mostrou que o uso de EDC/NHS alterou a morfologia levando a formação de poros interconectados. Nos ensaios de absorção em tampão de PBS foi observado que o uso de ácido acético aumenta a absorção para as esponjas sem EDC/NHS, enquanto para as esponjas com EDC/NHS a absorção é maior quando se usa ácido adípico. Todas as esponjas foram não citotóxicas o que torna esses materiais promissores para serem estudados em aplicações na área médica, tais como material de curativo, implantes, liberação controlada de fármacos.Chitosan is a natural polymer studied in various fields such as environmental, food, pharmaceutical, biomedical and biotechnology. It can be obtained from different polymorphic forms of chitin, of which the form β has proven advantageous because it promotes more homogeneous and chemical modifications leads to a final product less allergenic. Chitosan can be combined with other compounds and thus further improve its properties. The aim of this study was to analyze how the use of adipic acid, replacing acetic acid affects the properties of gels and sponges of chitosan and chitosan/gelatin, which were subsequently crosslinked with EDC/NHS. The techniques used for these studies were: rheology, FTIR, SEM, absorption in PBS and cytotoxicity assays. In rheology, it was observed that increasing the concentration of chitosan was possible to prepare more elastic and viscous gels. The same occurs in the presence of gelatin or EDC/NHSO. The effect of the use of adipic acid to replace the acetic acid was also shown on rheological measurements, because the gels with 2% chitosan or chitosan/gelatin without EDC/NHS were more elastic and more viscous when the adipic acid has been used. The FTIR spectra showed the presence of interactions between chitosan and gelatin and the formation of amide II Bonds after crosslinking with EDC/NHS. In the preparation of the sponges it was observed that the gels of chitosan with adipic acid generated unstable sponges crumbled during neutralization, but this instability does not occur with the blend. Sponges prepared with the blend were studied after neutralization and SEM showed that the use of EDC/NHS altered the morphology leading to the formation of interconnected pores. The use of acetic acid increases the absorption in PBS for sponges without EDC/NHS, while for sponges with EDC/NHS the absorption is greater when adipic acid was used. All sponges were non-cytotoxic making them promising materials to be studied for applications in the medical field, such as dressing materials, implants, controlled drug release.
23
Pereira, Járede Carvalho [UNESP]. "Avaliação do processo de reparo em defeitos de calvária de ratos com membrana de celulose bacteriana e membrana de colágeno porcino: análise histológica, histométrica e imunoistoquímica." Universidade Estadual Paulista (UNESP), 2017. http://hdl.handle.net/11449/151489.
Full textAbstract:
Submitted by Jarede Carvalho Pereira null (dr.jarede@hotmail.com) on 2017-08-30T17:29:26Z
No. of bitstreams: 1
Tese Járede.pdf: 2356458 bytes, checksum: 4637812d3b83b5f71fecba5d9a1af034 (MD5)Approved for entry into archive by Luiz Galeffi (luizgaleffi@gmail.com) on 2017-08-30T18:09:15Z (GMT) No. of bitstreams: 1 pereira_jc_dr_araca.pdf: 2356458 bytes, checksum: 4637812d3b83b5f71fecba5d9a1af034 (MD5)
Made available in DSpace on 2017-08-30T18:09:15Z (GMT). No. of bitstreams: 1 pereira_jc_dr_araca.pdf: 2356458 bytes, checksum: 4637812d3b83b5f71fecba5d9a1af034 (MD5) Previous issue date: 2017-08-07
Este estudo objetivou avaliar a eficácia da membrana de celulose bacteriana (Nanoskin®) no reparo ósseo de defeitos críticos de 8mm em calota de ratos machos adultos quando comparada à membrana colágena Bio-Gide®. Foram utilizados 72 ratos machos adultos divididos em três grupos experimentais: grupo coágulo (GC), grupo Bio-Gide® (BG) e grupo chá verde (CV). Os períodos de estudo foram de 7, 14 30 e 60 dias após a criação do defeito cirúrgico e aposição da membrana. Foram realizadas a análise histológica, histométrica e imunoistoquímica. Foi possível observar que aos 30 e 60 dias de reparo, o grupo BG apresentou melhor preenchimento do defeito cirúrgico, com maior quantidade de tecido ósseo. Já o grupo CV apresentou preenchimento do defeito com grande quantidade de tecido conjuntivo maduro. Os dados obtidos na análise histométrica revelam que aos 30 e 60 dias a área de osso neoformado teve grande discrepância para o grupo BG em relação ao CV e GC (Teste de Tukey - P<0,001). Por outro lado, os resultados referentes à análise por imunistoquímica evidenciam marcações moderada e intensa para as proteínas osteocalcina (OC) e osteopontina (OP) tanto para o grupo BG quanto para o CV aos 60 dias de reparo. Pode-se concluir que apesar de a membrana de chá verde apresentar aspectos promissores no reparo de tecido mole, neste estudo não permitiu o reparo ósseo em calotas de ratos, quando comparada à Bio-Gide®.
The present study aimed to evaluate the efficiency of bacterial cellulose membrane (Nanoskin® ) in the bone repair of 8 mm critical-size defects in male adult rat calvaria compared to collagen membrane BioGide® . It was used 72 adult male rats divided into three experimental groups: Clot group (CG), Bio-Gide® group (BG) and bacterial cellulose group (BC). The study period were seven, 15, 30 and 60 days after the surgical defect and position of the membrane. It were performed the histologic, histometric and imunohistochemistry analysis and possible to observe that at 30 and 60 days, BG group showed higher filling of the surgical wound with higher amount of new formed bone. The BC group showed a mature connective tissue filling the defect. Data from histometric analysis showed that at 30 and 60 days the new bone formed area was discrepant for BG group compared with BC and CG group (Tukey test – P<0,001). On the other hands, immunohistochemistry analysis showed a moderate and intense immunolabeling of osteocalcin and osteopontin at 60 days of bone repair for BG and BC group. It was possible to conclude that despite the BC membrane showing promising aspects in the soft tissue repair, did not allow bone repair in rats calvaria, compared to BioGide®.
24
Guo, Weidun. "Infections associated with intraperitoneal biomaterials an experimental study on bacterial adherence to biomaterials and enteric bacterial translocation induced by intraperitoneal biomaterials /." Lund : Lund University, 1993. http://catalog.hathitrust.org/api/volumes/oclc/39737932.html.
Full text
25
Queiroz, Lucas Araújo 1982. "Avaliaçao do uso das proteínas derivadas da matriz do esmalte e de substituto ósseo sintético em lesões de bifurcação grau II mandibulares = estudo clínico controlado e randomizado." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/290832.
Full textAbstract:
Orientador: Enilson Antônio SallumDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-17T16:35:38Z (GMT). No. of bitstreams: 1 Queiroz_LucasAraujo_M.pdf: 23764982 bytes, checksum: 9d01ff7e493a0eb69a8166673d96fe1b (MD5) Previous issue date: 2011
Resumo: O objetivo do presente estudo foi avaliar clinicamente, a utilização das proteínas derivadas da matriz do esmalte (EMD) e do Beta-tricálciofosfato/ hidroxiapatita (?TCP/HA), isolado ou em associação, no tratamento de lesões de bifurcações classe II mandibulares. Foram utilizados neste estudo 25 pacientes adultos, que apresentavam lesões de bifurcações classe II livres (HAMP et al, 1975). Os pacientes foram aleatoriamente divididos em dois grupos: grupo um (n=13) - acesso cirúrgico para raspagem e alisamento radicular e ?TCP/HA e grupo dois (n=12) - acesso cirúrgico para raspagem e alisamento radicular e associação EMD ?TCP/HA. Os seguintes parâmetros clínicos: Índice de Placa (IP), Sangramento à Sondagem (SS); Posição da Margem Gengival Relativa (PMGR), Profundidade de Sondagem (PS), Nível de Inserção Clínico Vertical Relativo (NICVR), Nível de Inserção Clínico Horizontal Relativo (NICHR) foram avaliados antes do procedimento cirúrgico e após 6 meses. Após o período de acompanhamento, o ganho médio no nível clínico de inserção vertical foi de 2,33 mm para o grupo um e de 1,58 mm para o grupo dois. Com relação ao nível de inserção clínico horizontal as médias de ganho foram de 2,58 mm e 2,67 mm para o grupo um e dois respectivamente. Ambos os grupos não apresentaram diferença clínica estatisticamente significante entre eles. Pode-se concluir que, os dois procedimentos são eficazes no tratamento de lesões de bifurcação classe II mandibulares
Abstract: The aim of the present clinical trial is to evaluate the associated use of enamel matrix derivative proteins with a graft material including beta-tricalcium phosphate and hydroxyapatite for the treatment of class II furcation defects. Twenty five patients presenting mandibular class II furcation involvements were selected (HAMP et al, 1975). The patients were randomly assigned to: Group one (n=13) - Open Flap Debridement + beta-tricalcium phosphate in association with hydroxiapatyte (? TCP-HA); Group two (n=12) - Open Flap Debridement (OFD) + Enamel matrix derivative proteins (EMD) + beta-tricalcium phosphate in association with hydroxiapatyte (? TCP-HA); Plaque Index (PI), Bleeding on Probing (BOP), Probing Depth (PD), Relative Gingival Margin Position (GMPR), Relative Vertical and Horizontal Clinical Attachment Level (RVCAL and RHCAL), were evaluated at baseline and 6 months after the surgeries. After the following period the mean vertical attachment level was 2,33 mm for the group one and 1,58 mm for the group two. For the horizontal attachment level the mean gain was 2,58 mm and 2,67 mm for the group one and two respectively. Both groups did not show any statistic difference between them. It can be concluded that both procedures are capable in the treatment of mandibular class II furcation defects
Mestrado
Periodontia
Mestre em Clínica Odontológica
26
Calvão, Patrícia Schmid. "Obtenção e caracterização de misturas do polímero biodegradável P[3HB] e seu copolímero P[3HB-co-3HV] com elastômeros." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3133/tde-29092010-164518/.
Full textAbstract:
Neste trabalho foi desenvolvido um estudo com o poliéster biodegradável P[3HB] (poli[R-3-hidroxibutirato]) e seu copolímero P[3HB-co-3HV] (poli[R-3-hidroxibutirato-co-3- hidroxivalerato]). Esses materiais são conhecidos por seu grande potencial de biodegradabilidade, porém sua utilização pela indústria ainda é limitada em função de seu baixo desempenho mecânico. Visando a tenacificação desses materiais, optou-se por misturá-los com os elastômeros EPDM (terpolímero de etileno-propileno-dieno) e PVB (Poli(vinil butiral)). Foram estudados quatro grupos de blendas: P[3HB]/EPDM e P[3HB-co- 3HV]/EPDM processados em misturadores internos e posteriormente prensadas em filmes; P[3HB]/EPDM e P[3HB]/PVB extrudados e posteriormente injetados. As blendas foram obtidas nas concentrações de 10, 20 e 30% em peso de elastômeros. Inicialmente, estudou-se efeito da incorporação de elastômeros na cristalinidade, estrutura cristalina, propriedades térmicas e dinâmico-mecânicas das matrizes, e o efeito do tipo de processamento utilizado. Observou-se que a adição dos elastômeros às matrizes semicristalinas aumentou a nucleação de esferulitos, resultando em um aumento da cristalinidade das mesmas. O PVB apresentou um efeito plastificante na estrutura do PHB. Os filmes apresentaram uma degradação térmica maior que as amostras injetadas, resultando em uma cristalização mais lenta e um grau de cristalinidade maior. Em um outro estudo, avaliou-se a morfologia, tensão interfacial, comportamento reológico, propriedades mecânicas e a biodegradabilidade das amostras estudadas. Foi observada uma morfologia de dispersão de gotas para todas as misturas, exceto para a mistura P[3HB]/EPDM obtida por injeção que apresentou um certo grau de co-continuidade. No caso das misturas injetadas foi visto que o fator que parece influenciar mais fortemente em sua morfologia final são as razões de viscosidade observadas entre a matriz e a fase dispersa das mesmas. A adição de elastômeros aumentou a resistência ao impacto do P[3HB], principalmente no caso da mistura P[3HB]/EPDM, o que pode estar relacionado à morfologia co-contínua observada nesta blenda. A incorporação dos elastômeros resultou em uma redução do módulo de elasticidade e da resistência à tração do P[3HB], e aumento do alongamento, principalmente no caso da mistura com PVB. Foi visto que a biodegradação do P[3HB] e P[3HB-co-3HV] aumentou com a adição de elastômeros, devido à morfologia de dispersão e a diminuição do tamanho dos esferulitos que aumentam a área interfacial para a ação das enzimas, facilitando a biodegradação.In this work a study with the biodegradable polyester P[3HB] (poly[R-3- hydroxybutyrate]) and its copolymer P[3HB-co-3HV] (poly[R-3-hydroxybutyrate-co-3- hydroxyvalerate]) was conducted. These materials are known for their high biodegradability but their use is still limited because of their poor mechanical properties. In order to improve these properties it was chosen to blend these biodegradable polymers with EPDM (Ethylene propylene diene monomer) and PVB (Polyvinyl butyral). Four groups of blends were obtained: P[3HB]/EPDM and P[3HB-co-3HV]/EPDM blends were prepared using an internal mixer and then compressed molded; P[3HB]/PVB and P[3HB]/EPDM blends were prepared using an extruder and further injected. The blend concentrations ranged from 10 to 30 wt. % of the rubbery phase. Initially, the effect of rubber type on the crystallinity, the crystalline structure, thermal and dynamic-mechanical properties of the matrices and the effect of processing method to obtain the blends were investigated. The addition of elastomers on P[3HB] (and P[3HB-co- 3HV]) increases the nucleation, resulting in an increase of matrix crystallinity. PVB showed a plasticizing effect on the P[3HB] structure. Film samples showed a higher thermal degradation than injected ones, resulting in a slower crystallization and higher crystallinity. The morphology, interfacial tension, rheological behavior, mechanical properties (tensile and impact) and biodegradability of samples were also studied. A droplet dispersion morphology type was obtained for all the blends except for P[3HB]/EPDM injected samples which presented some extent of degree of continuity. The experimental results indicated that the final morphology observed for the blends was controlled by the viscosity ratio between the matrix and dispersed phase. Elastomer addition increased P[3HB] impact strength mainly for P[3HB]/EPDM blends, probably due to its co-continuous morphology. Moreover, elastomer incorporation resulted in a decrease of P[3HB] elastic moduli and tensile strength and increase of elongation of break, mainly for P[3HB]/PVB blends. It was observed that P[3HB] and P[3HB-co-3HV] biodegradation increased with elastomer addition due to the droplet dispersion morphology and decrease of spherulites size witch causes an increase of interfacial area for enzymes, facilitating biodegradation.
27
Beck, Paul Beck Paul. "Magnetic field assisted biomaterials processing /." [S.l.] : [s.n.], 2009. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=18292.
Full text
28
Tang, Yi-wen. "Surface modifying macromolecules for biomaterials." Thesis, University of Ottawa (Canada), 1995. http://hdl.handle.net/10393/10318.
Full textAbstract:
In this thesis, new biomaterials were developed by incorporating surface modifying macromolecules (SMMs) that enriched the surface with a fluoro-chemistry. The SMMs contained a linear polyurethane as the prepolymer component and the prepolymer was end-capped by a fluorinated alcohol. The SMM materials and the blend of these SMMs with the polyester-urea-urethane base polymer were characterized with respect to their bulk and the surface properties, response to their biodegradation in the presence of enzyme and their fibrinogen adsorption characteristics. The SMMs were found to have selectively migrated to the surface of the polymer mixtures as expected. The bulk thermal (e.g. glass transition temperature) were found to be unaltered for polyurethane samples containing up to 5% SMM. The "fluorine tail" of the SMMs allowed the substrate surfaces to achieve very low surface wettability. Contact angle values (water/air) for the new materials were as high as $116\sp\circ,$ which is higher than that of $\rm Teflon\sp{R}.$ Measurements of fibrinogen adsorption, an indication of the tendency of surfaces to stimulate thrombosis, showed that the SMM blended materials significantly reduced fibrinogen adsorption. A biodegradation test of a polyether-urea-urethane containing one of the SMMs optimized for the polyester-urea-urethane showed that the SMM was unable to inhibit degradation of the polyether-urea-urethane. This suggested that the SMM was not universally effective and that the microstructure of, and the interaction between, SMMs and the base polymer were also important factors to be considered during the investigations of the stability of polyurethanes. (Abstract shortened by UMI.)
29
López, Alejandro. "Injectable Biomaterials for Spinal Applications." Doctoral thesis, Uppsala universitet, Institutionen för teknikvetenskaper, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-215606.
Full textAbstract:
The use of injectable biomaterials is growing as the demands for minimally invasive procedures, and more easily applicable implants become higher, but their availability is still limited due to the difficulties associated to their design. Each year, more than 700,000 vertebral compression fractures (VCF’s) are reported in the US and 500,000 VCF’s in Europe due to primary osteoporosis only. VCF’s can compromise the delicacy of the spinal canal and also cause back pain, which affects the patient’s quality of life. Vertebroplasty was developed in the 80’s, and has proven to be a safe minimally invasive procedure that can, quickly and sustainably, relieve the pain in patients experiencing VCF’s. However, biomaterials for vertebroplasty still have limitations. For instance, ceramic bone cements are difficult to distinguish from the bone using X-ray techniques. On the other hand, acrylic bone cements may cause adjacent vertebral fractures (AVF’s). Large clinical studies have indicated that 12 to 20% vertebroplasty recipients developed subsequent vertebral fractures, and that 41 to 67% of these, were AVF’s. This may be attributed to the load shifting and increased pressure on the adjacent endplates reached after vertebroplasty with stiff cements. The primary aim of this thesis was to develop better injectable biomaterials for spinal applications, particularly, bone cements for vertebroplasty. Water-soluble radiopacifiers were first investigated to enhance the radiopacity of resorbable ceramic cements. Additionally, different strategies to produce materials that mechanically comply with the surrounding tissues (low-modulus bone cements) were investigated. When a suitable low-modulus cement was produced, its performance was evaluated in both bovine bone, and human vertebra ex vivo models. In summary, strontium halides showed potential as water-soluble radiocontrast agents and could be used in resorbable calcium phosphates and other types of resorbable biomaterials. Conversely, linoleic acid-modified (low-modulus) cements appeared to be a promising alternative to currently available high-modulus cements. It was also shown that the influence of the cement properties on the strength and stiffness of a single vertebra depend upon the initial bone volume fraction, and that at low bone volume fractions, the initial mechanical properties of the vertebroplasty cement become more relevant. Finally, it was shown that vertebroplasty with low-modulus cements is biomechanically safe, and could become a recommended minimally invasive therapy in selected cases, especially for patients suffering from vertebral compression fractures due to osteoporosis.
30
Cairns, Scott. "Biofilms : biomaterials and chronic wounds." Thesis, Cardiff University, 2012. http://orca.cf.ac.uk/50559/.
Full textAbstract:
Healthcare associated infections (HCAIs) are a large and growing problem. Bacterial infections of patients and on the medical devices used to treat them represent a significant source of morbidity and mortality. There is also a significant economical impact to the healthcare system attributed to HCAIs. While bacterial infections per se are not a novel problem, the discovery of an adherent polymicrobial phenotype called a biofilm is. A biofilm is defined by its structure and the community of bacteria therein. This study investigated bacteria biofilms in a number of pertinent clinical scenarios. To achieve this, samples were taken from five different but related clinical areas where biofilms are known to infect or are suspected to, namely endotracheal tubes, tracheostomy tubes, burn wounds, chronic wounds and chronic wound dressings. Samples were analysed using microbiological and molecular analysis techniques, the latter included polymerase chain reactions, species-specific PCR and denaturing gradient gel electrophoresis to assess microbial diversity. Fluorescent in-situ hybridization was used subsequently to analyse species orientation and biofilm structure within the biofilm. This study showed a diverse bacterial population in all the samples, with the presence of oral biota in the ETT specimens, changing to commensal bacteria over time. Large threedimensional biofilm structures were present in the specimens confirming the presence of biofilms, and within one of the chronic wound dressings where a complex biofilm was visible within the matrix of the dressing itself. These findings have considerable significance clinically, not only in demonstrating the need for biofilm targeted diagnostic techniques, but also in highlighting the need for specific biofilm treatment modalities in critical care, burn services and chronic wound management.
31
Wells, Tyrone. "Lignin for bioenergy & biomaterials." Diss., Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/53575.
Full textAbstract:
Sustainable waste treatment and lignin development strategies targeted for biorefineries will benefit industry, consumers, and the environment. This dissertation demonstrates the feasibility of a novel biochemical pathway capable of converting sugars and lignin sourced from biorefinery waste streams into microbial oils suitable for biodiesel, cosmetic, and biopharmaceutical applications. This biochemical pathway also presents interesting avenues for the commercial production of higher-value intermediate metabolites such as catechol, protocatechuate, pyruvate, and succinate. Alternatively, this dissertation also demonstrates a unique polymerization strategy for lignin that can be adopted towards the production of green polymeric biomaterials. Overall, these strategies jointly present intriguing routes for lignin valorization.
32
Unosson, Erik. "Antibacterial Strategies for Titanium Biomaterials." Doctoral thesis, Uppsala universitet, Tillämpad materialvetenskap, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-249181.
Full textAbstract:
Titanium and titanium based alloys are widely used in dentistry and orthopedics to replace hard tissue and to mend broken bones. It has become a material of choice due to its low density, high strength, good biocompatibility and its capacity to integrate closely with the bone. Today, modern materials and surgical techniques can enable patients to live longer, and aid in maintaining or regaining mobility for a more fulfilling life. There are, however, instances where implants fail, and one of the primary causes for implant failure is infection. This thesis deals with two possible ways of reducing or eliminating implant associated infections; TiO2 photocatalysis, where a surface can become antibacterial upon irradiation with UV light; and incorporation of silver, where a subsequent release of silver metal ions result in an antibacterial effect. For the TiO2 photocatalysis strategy, a simple and cost effective chemical oxidation technique, using hydrogen peroxide (H2O2) and water, was used to create an active TiO2 surface on titanium substrates. This surface was shown to effectively degrade an organic model substance (rhodamine B) by generating reactive oxygen species (ROS) under UV illumination. However, it was shown that Ti-peroxy radical species remaining in the surface after the H2O2-oxidation process, rather than generation of ROS from a heterogeneous photocatalytic process, was responsible for the effect. This discovery was further exploited in a TiO2/H2O2/UV system, which demonstrated synergy effects in both rhodamine B degradation tests and in antibacterial assays. For the silver ion release strategy, a combinatorial materials science approach was employed. Binary Ag-Ti oxide gradients were co-deposited in a reactive (O2) environment using a custom built physical vapor deposition system, and evaluated for antibacterial properties. The approach enabled synthesis and composition-structure-property evaluation unlikely to have been achieved by traditional means, and the gradient coatings demonstrated antibacterial properties against both S. aureus and S. epidermidis according to silver ion release. The release was shown to depend more on structural features, such as surface area, crystallinity and oxidation state, than on composition. Ag-Ti oxide gradients were also evaluated under UV illumination, as Ag deposits on crystalline TiO2 can enhance photocatalytic properties. In this work, however, the TiO2 was amorphous and UV illumination caused a slight reduction in the antibacterial effect of silver ions. This was attributed to a UV-induced SOS response in the S. epidermidis bacteria. The results of this thesis demonstrate that both TiO2 photocatalysis, or UV induced activation of Ti-peroxy radical species, as well as incorporation of silver are viable antibacterial strategies for titanium biomaterials. However, their clinical applications are still pending risk-benefit analyses of potential adverse host tissue responses.
33
Baldwin, Lisa Michelle. "The immune response to biomaterials." Thesis, University of Liverpool, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.420298.
Full text
34
Ahn, Edward Sun 1972. "Nanostructured apatites as orthopedic biomaterials." Thesis, Massachusetts Institute of Technology, 2001. http://hdl.handle.net/1721.1/8627.
Full textAbstract:
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2001.Includes bibliographical references.
Historically, using suitable mechanical replacements for bone has been a priority in designing permanent, load-bearing orthopedic implants. As a result, the biomaterials used in these implants have been largely limited to bioinert titanium-based alloys, as well as to polycrystalline alumina and zirconia ceramics. However, analysis of implants incorporating these traditional biomaterials indicated that most failures involved an unstable implant-tissue interface and/or a mismatch of the mechanical behavior of the implant with the surrounding tissues. As a result, up to 20% of patients receiving permanent, load-bearing implants may undergo a revision operation. The objective of this research was to develop an alternative biomaterial that combined both mechanical resilience and an osteoconductive surface to provide a stable interface with the surrounding connective tissue so that the need for revision operations may be significantly reduced. In the effort to address the issue of mechanical strength and bioactivity simultaneously, hydroxyapatite (HAP) has generated considerable interest. Though a commonly used bioceramic, HAP has been limited by its processability. This material is sensitive to non-stoichiometry and impurities during synthesis and processing due to its complex composition and crystal structure (Ca10(P04)6(OH)2, P63/m).
(cont.) Consequently, conventionally processed HAP materials lack phase purity and homogeneity. Densification of HAP requires high temperatures that result in grain growth and decomposition into undesired phases with poor mechanical and chemical stability. To circumvent densification at high temperatures, glassy additives have been introduced to promote liquid-phase sintering at a lower temperature. However, the presence of a secondary glassy phase gave rise to poor mechanical characteristics. Hence, clinical applications of HAP have been limited to powders, coatings, porous bodies, and non-load-bearing implants. To overcome the deficiencies of conventionally processed HAP, nanostructure processing was applied, which allowed for materials design from the molecular level. By using an aqueous chemical precipitation technique, a fully dense, transparent, nanostructured HAP-based bioceramic that exhibited superior mechanical properties and enhanced tissue bonding was obtained. Processing parameters affecting the molecular and structural development of HAP were used to tailor HAP stoichiometry, crystallite size, morphology and surface chemistry for optimal thermal stability and sinterability. Unlike conventionally processed HAP, the stoichiometric, equiaxed, nanocrystalline HAP powders demonstrated significantly enhanced sinterability by fully densifying at a remarkably low temperature of 900ʻC with pressure-assisted sintering.
(cont.) Furthermore, high-resolution electron micrographs illustrated that the sintered compact possessed a uniform and ultrafine microstructure with an average grain size of -100 nm, with no glassy or amorphous interfaces along the grain boundaries. The crystallinity of the HAP grains and grain boundaries and the minimal flaw sizes could be credited for the superior strength of nanostructured HAP compared to conventional HAP. Compared to polycrystalline HAP, nanocrystalline HAP also provided greater osteoblast function. In vitro experiments indicated that nanocrystalline HAP surfaces enhanced cell attachment, proliferation and mineralization. The larger grain boundary volume resulting from the ultrafine microstructure might have enhanced protein adsorption, ...
by Edward Sun Ahn.
Ph.D.
35
De, Castro Bras Lisandra Eunice. "Characterisation of collagen-derived biomaterials." Thesis, Brunel University, 2009. http://bura.brunel.ac.uk/handle/2438/6597.
Full textAbstract:
One of the main problems in healthcare is the loss or failure of organs or tissues resulting from diseases, post-surgery complications, trauma or organ failure. As a result of tissue and organ shortage, there is a need for biomaterials designed to promote tissue regeneration resulting in good quality repair of tissues or organs, to maintain or repair biological function. Collagen, as one of the main proteins in the human body, has been extensively used in the development of biomaterials which can be used as tissue substitutes or can assist in tissue regeneration. Before commercialisation is allowed all biomaterials must prove to be functional and suitable for clinical use. Therefore, the evaluation of biomaterials requires rigorous and relevant testing. Biomaterials must be able to perform with an appropriate host response in a specific application. Tests must provide information to understand the host response, long-term outcome and issues pertaining to these. In the research reported in this thesis, an acellular porcine derived cross-linked collagen-based biomaterial (Permacol surgical implant) was analysed with a wide range of evaluation and compared to acellular noncross-linked and cellular, naturally cross-linked, equivalents. These matrices were characterized relating to their structure, composition and mechanical and biochemical properties. In addition, biological characterisation was performed through several studies designed to evaluate and compare biological responses in vitro, as well as in situ assessment of biocompatibility and effectiveness as a repair material and as bulking tissue. Permacol surgical implant was shown to be biocompatible, effective and efficient when used as bulking tissue and for soft tissue repair; furthermore, this biomaterial was resistant to enzymatic digestion and tolerant to bacterial presence suggesting that it could be used in some complicated clinical situations.
36
Molina, García Brenda Guadalupe. "Modified polymers as electroactive biomaterials." Doctoral thesis, Universitat Politècnica de Catalunya, 2020. http://hdl.handle.net/10803/673048.
Full textAbstract:
Development of polymeric biomaterials with tailored properties is essential for expanding biotechnologies and, therefore, proposing novel solutions for diagnostic and treatments in modern medicine. In order to contribute with such expansion, this research suggests different strategies to modify intrinsically conducting polymers (ICPs) and overcome their few limitations. Three main engineering approaches were used to combine ICPs advantages with others from conventional insulating polymers and biopolymers, optimizing their performance as electrochemical biomaterials on tissues engineering, biomimetic platforms, actuators and specially on the biosensing field.
The first strategy evaluated in this Thesis was designed to take advantage of the “grafting-through”technique and prepare graft copolymers with ICPs backbones. The incorporation of well-known biocompatible polymers like polyethylene glycol (PEG) and polycaprolactone (PCL) into ICP backbones, increased the cell viability in presence of the synthetized copolymers. Such modifications and the ICPs electroactivity allowed to estimate the copolymers performance as electrochemical sensors of biomolecules.
The second approach was planned to prepare free-standing, flexible and electroactive films for the electrochemical detection of bacterial infections. The excellent mechanical properties of isotactic polypropylene (i-PP) plastic, combined with an ICP like poly (3,4-ethylendioxythiophene) (PEDOT), enabled the obtained a novel composite with good dimensional stability to be applied as electrochemical platform for bacterial detection. This composite was able to perceive extracellular nicotinamide adenine dinucleotide (NADH), generated from the respiration reactions of bacteria, and distinguishing prokaryotic microbes from eukaryotic cells. In addition, with a small adjustment, the generated films exhibited qualities as electroactive bioplatforms for tissue engineering.
Finally, the third strategy fashioned an electroactive multi-functional nanomembrane for applications of flexible biomedical implants. A layer-by-layer assembly (LbL) was used to integrate the PEDOT electroactivity to the poly(lactic acid) (PLA) biopolymer. The self-supported nanomembrane of 5 layers, showed benefits as biomimetic platforms for selective ion and ATP transport, as well as actuator/artificial muscles.
Overall, the characterization studies of the electroactive and biocompatible composites presented in this Thesis, offer a comprehensive view on how modifications in ICPs optimize its abilities as biomaterials and open a wide range of possible applications in biomedicine.El desarrollo de biomateriales poliméricos con propiedades específicas, es esencial para la expansión biotecnológica y, por lo tanto, para el diseño de soluciones novedosas en el diagnóstico y tratamientos de enfermedades en la medicina moderna. Con el objetivo de contribuir con dicha expansión, esta investigación propone diferentes estrategias de modificación en polímeros conductores intrínsecos (ICPs por sus siglas en ingles), y superar con ello sus pocas limitaciones. Tres principales enfoques de ingeniería fueron utilizados para combinar las ventajas de ICPs con las de otros polímeros convencionales y biopolímeros, optimizando su rendimiento como biomateriales electroquímicos en ingeniería de tejidos, plataformas biomiméticas, actuadores y, especialmente, en el campo de la biodetección. La primera estrategia evaluada en esta Tesis, fue diseñada para aprovechar la técnica de injerto y preparar copolímeros con una cadena principal de ICP. Empleando esta técnica, la incorporación de polímeros biocompatibles, como el polietilenglicol (PEG) y la policaprolactona (PCL), en la cadena principal de un ICP, aumentó la viabilidad celular en presencia de los copolímeros formados. Dichas modificaciones y la electroactividad de los ICPs, permitieron estimar el rendimiento de los copolímeros como sensores electroquímicos de biomoléculas. El segundo enfoque fue planeado para preparar películas auto soportables, flexibles y electroactivas, que permitieran la detección electroquímica de infecciones bacterianas. Las excelentes propiedades mecánicas del polipropileno isotáctico (i-PP) en combinación con un ICP, como el poli (3,4-etilendioxitiofeno) (PEDOT), permitieron obtener un nuevo compuesto electroquímico capaz de percibir el dinucleótido adenina de nicotianamina (NADH por su siglas en ingles), generado extracelularmente durante las reacciones respiratorias de las bacterias, y distinguir los microbios procariotas de las células eucariotas. Además, con un pequeño ajuste, las películas generadas exhibieron cualidades como bioplataformas electroactivas para la ingeniería de tejidos. Finalmente, con la tercera estrategia se diseñó una nanomembrana electroactiva multifuncional, para aplicaciones de implantes biomédicos flexibles. Un ensamble de capa por capa, fue utilizado para integrar la electroactividad del PEDOT con el biopolímero ácido poli láctico (PLA por sus siglas en ingles). La nanomembrana auto soportable de 5 capas, mostró beneficios como plataforma biomimética para el transporte selectivo de iones y adenosín trifosfato; o como músculos artificiales o actuadores. En general, los estudios de caracterización de los compuestos electroactivos y biocompatibles presentados en esta Tesis, ofrecen una visión integral de cómo las modificaciones en los ICPs optimizan sus capacidades como biomateriales, y abren una amplia gama de posibles aplicaciones en biomedicina.
37
Sabnis, Subodh Sushil. "Vibrational spectroscopy of amphiphilic biomaterials." Thesis, Sheffield Hallam University, 2009. http://shura.shu.ac.uk/20305/.
Full textAbstract:
The technique of ATR-FTIR has been used to study the rates of diffusion of water and two different protein solutions into hydrogels, in the form of thin films, synthesised "in-situ" onto the surface of an ATR crystal. The work involved making copolymers and crosslinked gels of glycerol monomethacrylate (GMMA), lauryl methacrylate (LMA) and ethylene glycol dimethacrylate (EGDMA).Bands characteristic of the individual monomers could not be identified once a stock solution was made up. The rates of reaction were determined from the integrated area of the broad band at 815 cm[-1], which was designated as a monomer band. This band decreased in intensity as the polymerisation progressed. Similarly, a band at 750 cm[-1], designated as a polymer band, made an appearance and increased in intensity throughout the course of the polymerisation. Attempts were made to fit the reaction kinetics to first and second order reactions, using the linear part of the plot of the integrated area of the 815 cm[-1] band. However no particular trend could be found with increase in amounts of crosslinker for each formulation. The reaction possibly followed complex kinetics and this simplistic approach was not really applicable. Diffusion of deionised water into the synthesised gels was studied for three differentformulations. It was found that the diffusion coefficient was of the order of 10[-5] cm[2] s[-1] for the diffusion of water into the gels and decreased with increasing crosslinker concentration, except in the case of 100% GMMA with 0% crosslinker. The dissolution of the GMMA segments in the GMMA-EGDMA copolymer, was further confirmed by using ESEM. The gels with all other formulations were found to be morphologically featureless when looked at in the ESEM chamber. Four water bands were fitted to the &ugr;(OH) stretching region of each spectrum during diffusion and diffusion coefficients of each types of water were calculated. Diffusion of a 30% saline solution of bovine serum albumin was studied for the synthesised gels. It was found in each case, that only the water from the saline solution permeated through the polymer, leaving the protein in the form of a deposit on the top of the gel. The molecular weight of the protein (65kDa) was responsible for the latter not diffusing through the gel. The pores on the gel surface could not swell to an extent large enough to allow the passage of this bulky protein. Hence the gel acted as a selectively permeable membrane allowing passage of molecules based on their molecular weights. The order of magnitude of the diffusion coefficient for the saline water was the same as that of pure water. Diffusion of a solution of lysosyme containing 1% by volume of lysosyme, 49% by volume of water and 50% by volume of glycerol was characterised by a typical two step diffusion process. The first step was rather rapid and could possibly be due to water uptake from the solution. The second step showed evidence of glycerol permeating through the gel. It was impossible to distinguish the protein from the water and glycerol due to its concentration. Diffusion experiments were also carried out with a 10% solution of lysosyme in D[2]O. It was found that a single stage diffusion profile resulted in this case for the D2O . The protein definitely permeated into the gel in this case and it was possible to distinguish the amide I band. All the D[2]O first permeated into the gel and increased the pore size by swelling of the gel. The protein was then seen to permeate into the polymer.
38
Murphy, Emma F. "Reduced protein adsorption on biomaterials." Thesis, University of Surrey, 1999. http://epubs.surrey.ac.uk/844207/.
Full textAbstract:
The adsorption of lysozyme, bovine serum albumin (BSA) and fibrinogen onto the surfaces of a number of poly (methacrylate) based, phosphorylcholine (PC)-containing polymer films has been characterised by neutron reflection and spectroscopic ellipsometry. The work represents the first systematic study of these biocompatible materials, attempting to establish the relationship between the structure of the films and their effectiveness in reducing protein adsorption. The polymer surface was formed by dip-coating a thin film of polymer onto the polished silicon oxide. As the extent of reduction in protein adsorption may depend upon how the film is coated, initial work was to examine the effect of the coating conditions. We show that the improvement of the smoothness of the outer film surface can lead to the formation of a close-packed PC layer, resulting in the reduction of protein adsorption. The subsequent experiment was focused on the two model PC-polymers with (PC100B) and without (PC100A) 5% silyl cross-linking groups. It was found that although the structures of the films were drastically different, the residual amount of proteins adsorbed was comparable, indicating that the outer surfaces of the two films were similar in composition. The preliminary measurements using partially deuterated PC100B containing 5% silyl groups show that there is a preferential segregation of the hydrophobic and hydrophilic groups across the film, with the hydrophilic groups enriched at the outer surface. This work offers the first experimental evidence of the preferential expression of PC groups on the outer surface. In order to demonstrate the effectiveness of the PC-polymer surfaces in reducing protein adsorption, some parallel work has also been done on the model surfaces of bare SiO2, hydrophobed SiO2 and PMMA (polymethylmethacrylate). It was found that under similar solution conditions the PC-polymer surfaces can reduce protein adsorption by a factor of 3-5. It is particularly interesting that PC-polymer surfaces are most effective at deterring adsorption of large fibrous proteins, such as fibrinogen.
39
Kalinichenko, T. G., and S. N. Danilchenko. "Nanoscale Apatite Biomaterials for Osteointegration." Thesis, Sumy State University, 2013. http://essuir.sumdu.edu.ua/handle/123456789/35471.
Full textAbstract:
The thermal behavior of bone tissue has been investigated in order to assess how it is affected struc-turally by incineration. The need of the development of such technology is caused by big number of pa-tients with oncology and dystrophic bone tissue diseases which use the artificial bone tissue replacement. The samples like small plates that cut from local area of bone fragment, were exposed to annealing in tem-perature range 560-720 C and were characterized by XRD, SEM, EPMA, XPS and method of differential dissolution.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35471
40
Yang, Jun. "Immune response to orthopaedic biomaterials." Case Western Reserve University School of Graduate Studies / OhioLINK, 1995. http://rave.ohiolink.edu/etdc/view?acc_num=case1058195837.
Full text
41
Davies, Stuart M. "Cellular responses to potential biomaterials." Thesis, Aston University, 1991. http://publications.aston.ac.uk/9696/.
Full textAbstract:
The aim of this study was to systematically investigate the factors considered to be responsible for anchorage-dependent cell behaviour to determine which, if any, of these factors exerts greater influence. An efficient means of doing so is the in vitro fibroblast cell culture model. The interaction of fibroblasts with novel substrata gives information about how a biological system reacts to a foreign material. The may ultimately lead to the development of improved biomaterials. This interdisciplinary study combines the elements of surface characterisation and biological testing to determine the nature of the biomaterial/host interface. Polarity and surface charge were found to have an important influence on fibroblast adhesion to hydrogel polymers, by virtue of their water-structuring effects. The same factors were found to affect cell adhesion on undegraded PHB-HV copolymers and their blends with polysaccharides. On degraded PHB-HV copolymers, the degradation process itself played the greatest role in influencing cell response. Increasing surface charge and mechanical instability in these polymers inhibited cell adhesion. Based on the observations of hydrogels and PHB-copolymers a novel material, gel-spun PHB was designed for use as a wound scaffold. In vitro tests using human and mammalian fibroblasts accentuated the importance of polarity and surface charge in determining cellular response. The overall view of cellular behaviour on a broad spectrum of materials highlighted the effects that polarity and surface charge have on water-structuring, and how this affects interfacial conversion. In degradable systems, mechanical stability also plays an inportant role in determining anchorage-dependent cell behaviour.
42
Graham, Christopher D. "Cellular interaction with novel biomaterials." Thesis, Aston University, 1998. http://publications.aston.ac.uk/9595/.
Full textAbstract:
The objective of this thesis is to report the behaviour of mammalian cells with biocompatible synthetic polymers with potential for applications to the human body. Composite hydrogel materials were tested as possible keratoprosthetic devices. It was found that surface topography is an important consideration, pores, channels and fibres exposed on the surface of the hydrogels tested can have significant effects on the extent of cell adheson and proliferation. It is recommended that the core component is fabricated out of one of the following to provide a non cell adhesive base; A8, A11, A13, A22, A23. The haptic periphery fabricated out of one of the following would provide a cell adhesive composite; A16, A30, A33, A37, A38, A42, A43, A44. The presence of vitronectin in the ocular tissue appears to lead to higher cell adhesion to the posterior surface of a contact lens when compared to the anterior surface. Group IV contact lenses adhere more cells than Group II contact lenses - this may indicate that more protein (including vitronectin) is able to adhere to the contact lens due to the Group IV contact lenses high water content and ionic hydrogel matrix. Artificial lung surfactant analogues were found to be non cytotoxic but also decreased cell proliferation when tested at higher concentrations. Poly(lysine ethyl ester adipamide) [PLETESA] had the most favourable response on cell proliferation and commercial styrene/maleic anhydride (pMA/STY sp2) the most pronounced inhibitory response. The mode of action that decreases cell proliferation appears to be through membrane destabilization. Tissue culture well plates coated with PLETESA allowed cells to adhere in a concentration dependent manner, multilaminar liposomes possibly of PLETESA were observed in solution in PLETESA coated wells. Polyhydroxybutryate (PHB) and polyhydroxyvalerate (PHV) blends that contained hydroxyapatite were found to be the most cell adhesive material of those materials tested. The blends that were most susceptible to degradation adhered the most cells in initial stages of degradation. The initial slight increase in cell adhesion may be due to the increased rugosity of the material. As the degradation continued the number of cells adhering to the samples decreased, this may indicate that the polarity was inhibitory to cell adhesion during the later stages of degradation.
43
Di, Filippo Maria Francesca <1993>. "Applied biomaterials from sustainable sources." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amsdottorato.unibo.it/9901/1/DiFilippo_MariaFrancesca_tesi.pdf.
Full textAbstract:
If we look back in time at the history of humanity, we can state that our generation is living an era of outstanding efficiency and progress because of globalization and global competition, even if this is resulting in the rapid depletion of energy sources and raw materials.
The environmental impact of non-biodegradable plastic wastes is of increasing global concern: nowadays, imagining a world without synthetic plastics seems impossible, though their large-scale production and their extensive use have only spread since the end of the World War II. In recent years, the demand for sustainable materials has increased significantly and, with a view to circular economy, research has also focused on the enhancement and subsequent reuse of waste materials produced by industrial processing, intensive farming and the agricultural sector. Plastic polymers have been the most practical and economical solution for decades due to their low cost, prompt availability and excellent optical, mechanical and barrier properties. Biodegradable polymers could replace them in many applications, thus reducing the problems of traditional plastics disposability and the dependence on petroleum. Natural biopolymers are in fact characterized by a high biocompatibility and biodegradability and have already prompted research in the field of regenerative medicine.
During my PhD, my goal was to use natural polymers from sustainable sources as raw materials to produce biomaterials, which are materials designed to interface with biological systems to evaluate, support or replace any tissue, organ, or function of the body. I focused on the use of the most abundant biopolymers in nature to produce biomaterials in the form of films, scaffolds and cements. After a complete characterization, the materials were proposed for suitable applications in different fields, from tissue engineering to cosmetics and food packaging. Some of the obtained results were published on international scientific and peer-reviewed journals.
44
Barro, Ojeda Víctor. "Osteonecrosis of the femoral head treatment with advanced cell therapy and biomaterials in an experimental sheep animal model." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/666938.
Full textAbstract:
Introducción: La osteonecrosis de la cabeza femoral (ONCF) afecta principalmente a pacientes jóvenes y activos, sin tratamiento, la entidad progresa en pocos años hacia la deformidad e incongruencia articular, presentando en su etapa avanzada cambios degenerativos articulares, dolor y discapacidad funcional, generando un importante impacto socioeconómico. Aunque existen factores que han estado directamente relacionados con el ONCF (fracturas, corticosteroides, alcohol, irradiación, enfermedad de Caisson), la etiología y la patogénesis persisten inciertas. El tratamiento de la ONCF representa un gran desafío para el cirujano ortopédico debido a la gran variabilidad clínica y radiológica de esta entidad. El desarrollo de estudios experimentales representa una herramienta muy útil, ya que nos ayuda a terminar de definir la patogenia de la enfermedad y, al mismo tiempo, a estudiar nuevas opciones para los tratamientos preclínicos.
Materiales y métodos: El modelo experimental consistió en inducir experimentalmente osteonecrosis en la cabeza femoral derecha en ovejas adultas mediante la introducción de una sonda de crioterapia percutánea con un sistema de helio y argón. A las 6 semanas después de la inducción de ONCF, los animales se dividieron en tres grupos terapéuticos, la descompresión central se asoció con uno de los siguientes tratamientos, excepto para el grupo de control al que no se aplicará ningún tratamiento adicional: Grupo A: tratamiento con concentrado de médula ósea y gránulos de βTCP, Grupo B: tratamiento con rhBMP-2 y gránulos de βTCP, Grupo C: tratamiento de descompresión central aislado. Después de un seguimiento total de 12 semanas, las cabezas femorales obtenidas se fueron estudiadas mediante microtomografía computarizada (microCT), pruebas biomecánicas e histológicas para evaluar el potencial óseo regenerativo de cada tratamiento.
Resultados: La inducción de ONCF se realizó en 20 ovinos. Observamos una tasa de complicaciones del 40% que obligó a los animales a sacrificarse. Finalmente, se incluyeron 12 ovejas (4 por grupo) en el presente estudio. La lesión necrótica fue confirmada mediante el estudio histológico de todos los cilindros obtenidos en la cirugía de descompresión central. Se observó regeneración ósea en todos los grupos estudiados. No se observaron diferencias estadísticamente significativas entre los grupos de tratamiento por análisis histológico, biomecánico o MicroCT.
Conclusión: Un nuevo modelo preclínico modificado de ONCF mediante la administración mínimamente invasiva de crioterapia con gases de helio-argón induce a ONCF en las fases previas al colapso de manera segura, cuantitativa y reproducible. Los resultados de nuestro estudio no apoyan el uso rutinario de BMP-2 o concentrado de médula ósea asociado con los gránulos de β-TCP en el tratamiento de ONCF en fase pre-colapso.Introduction: Femoral head osteonecrosis (ONCF) mainly affects young and active patients, without treatment, the entity progresses in a few years towards deformity and joint incongruity, presenting at its advanced stage joint degenerative changes, pain and functional disability, generating an important socioeconomic impact. Although there are factors that have been directly related to the ONCF (fractures, corticosteroids, alcohol, irradiation, Caisson's disease), etiology and pathogenesis persist uncertain. The treatment of the ONCF represents a great challenge for the orthopedic surgeon due to the great clinical and radiological variability of this entity. The development of experimental studies represents a very useful tool since it helps us to finish defining the pathogenesis of the disease and at the same time study new options for preclinical treatments. Materials and Methods: The experimental model consisted of experimentally inducing osteonecrosis in the right femoral head in adult sheep by introducing a percutaneous cryotherapy probe with a helium and argon system. At 6 weeks after the induction of the ONCF, the animals were divided into three therapeutic groups, core decompression was associated with one of the following treatments, except for the control group to which no additional treatment was applied: Group A: Treatment with bone marrow concentrate and βTCP granules, Group B: Treatment with rhBMP-2 and βTCP granules, Group C: Isolated core decompression treatment. After a total 12-week follow-up the femoral heads obtained were studied by computerized microtomography (microCT), biomechanical tests, histological in order to evaluate the regenerative bone potential of each treatment. Results: Induction of ONCF was performed in 20 sheep. We observed a complication rate of 40% that forced the animals to sacrifice. Finally, 12 sheep (4 per group) were included in the present study. The necrotic lesion was confirmed by the histological study of all the cylinders obtained in the Core Decompression surgery. Bone regeneration was observed in all the studied groups. No statistically significant differences were observed between the treatment groups by histological, biomechanical or MicroCT analysis. Conclusion: A new modified preclinical model of ONFH using minimally invasive administration of cryotherapy with helium-argon gases induces ONFH in pre-collapse phases in a safe, quantitative and reproducible way. The results of our study do not support the routine use of BMP-2 or bone marrow concentrate associated with β-TCP granules in the treatment of pre-collapse ONFH.
45
PRINCIVAL, Iza Mirela Rodini Garcia. "Síntese de Derivado de Furano ligados em Dendrímero bis-MPA e sua atividade anticâncer." Universidade Federal de Pernambuco, 2015. https://repositorio.ufpe.br/handle/123456789/17327.
Full textAbstract:
Submitted by Irene Nascimento (irene.kessia@ufpe.br) on 2016-07-11T18:52:51Z
No. of bitstreams: 2
license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5)
dissertacao mirela princival.pdf: 5990746 bytes, checksum: e5bcac5bef195c004f889c65ad741483 (MD5)Made available in DSpace on 2016-07-11T18:52:51Z (GMT). No. of bitstreams: 2 license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) dissertacao mirela princival.pdf: 5990746 bytes, checksum: e5bcac5bef195c004f889c65ad741483 (MD5) Previous issue date: 2015-07-31
FACEPE
Descrevemos aqui, um estudo citotóxico comparativo utilizando uma biblioteca de compostos contendo a função furano, e o dendrímero Bis-MPA. Dos compostos furânicos testados, os que apresentaram melhor resultado citotóxico frente às células tumorais foram sintetizados em grande escala (5 g). Assim, estes compostos, puderam ser submetidos à estudos de incorporação física (por interações químicas) ou ligação química (via ligação covalente) ao dendrímero. No intuito de estudar os efeitos citotóxicos que ambos os sistemas poderiam apresentar, os testes foram realizados empregando as seguintes linhagens celulares HEP-2, HT-29, MCF-7, NCI-H292 e HL-60, correspondentes ao câncer de Carcinoma de laringe, Carcinoma de Cólon, Adenocarcinoma de Mama e Leucemia promielocítica aguda. Cada teste foi realizado em quadruplicata, utilizando os compostos com alto grau de pureza (>99%), e de um mesmo lote do material, para todos os testes de toxicidade. Os testes de citotoxicidade r com o dendrímero bis-MPA, foram realizados utilizando o composto comercial, porém com checagem de pureza via RMN antes de realizar os testes e as reações químicas. Todos os testes biológicos após serem realizados, foram analisados utilizando o método colorimétrico MTT. Em suma, este estudo levou ao preparo de compostos em escala de gramas, com alto grau de pureza, necessário para estudar a possibilidade de desenvolver novos ligantes bifuncionais, na tentativa de se construir dendrímeros polifuncionalizados, contendo moléculas que apresentaram atividade citotóxica em sua estrutura química. Esse estudo vem sendo explorado pelo grupo na tentativa de expandir essa linha de raciocínio, e tentar corroborar com estudos da literatura no que diz respeito ao mecanismo de ação, e como esses se comportam frente a células tumorais, em testes in vitro. Dentre os compostos que apresentaram boas respostas aos ensaios biológicos, dois deles merecem destaque por mostrarem-se substâncias extremamente eficazes em testes de inibição total das células. Estes compostos têm em comum um anel furano ligado diretamente a uma enona ou a um ácido acrílico (compostos 32 e 35 respectivamente).
Here we describe a comparative cytotoxic study by using a library of compounds containing a furan moiety and the dendrimer Bis-MPA. Among furan tested compounds against tumor cancer cells, those that have shown better results were synthesized in a large scale reaction (5 g). Thus, these compounds, which have shown high biological activity, underwent physical incorporation studies (for chemical interactions) or chemically linked (via covalent bond) with the dendrimer. In order to study the cytotoxic effects that could exhibit by both systems, tests were conducted using the following tumor cancer cells: HEp-2, HT-29, MCF-7 e HL60. Each test was performed in quadruplicate using the compounds in their high purity (>99%) and used as a single batch of material for all toxicity tests. The dendrimer Bis-MPA cytotoxic tests were conducted subjecting the commercial reagent although with a pre checked in its purity by NMR before do the tests and chemical reactions. All biological tests after have been done were analyzed using the MTT colorimetric method. In summary, this study has led to preparation of compounds in multi gram scale in a high purity, necessary to realize the possibility of developing new bifunctional links, in an attempt to build polifuncionalized dendrimers containing active cytotoxic active molecules in their chemical structure. This study is being explored by the group in an attempt to expand this line of reasoning, and try to corroborate with literature data regarding the mechanism of action, and their behavior against the tumor cancer cells in an in vitro tests. Among the compounds that showed good activity to biological assays, two of them are noteworthy due to their extremely effective activity in total inhibition tests of cells. These compounds have in common a furan ring attached to an enone or an acrylic acid (compounds 32 and 35 respectively).
46
Santos, Saulo Cabral dos. "Avaliação da utilização de esponja de chitosan/tricalcio fosfato no reparo de defeitos osseos em calvaria de ratos." [s.n.], 2007. http://repositorio.unicamp.br/jspui/handle/REPOSIP/290426.
Full textAbstract:
Orientadores: Antonio Wilson Sallum, Marcio Zaffalon CasatiTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba
Made available in DSpace on 2018-08-09T15:56:25Z (GMT). No. of bitstreams: 1 Santos_SauloCabraldos_D.pdf: 3210945 bytes, checksum: 72bba992ab8c1008b9016ed006981d75 (MD5) Previous issue date: 2007
Resumo: A grande busca da periodontia é regenerar nos indivíduos que portaram patologias periodontais as estruturas de suporte dental devastadas pela doença infecciosa. Nos últimos anos, materiais para enxertos ósseos vêm sendo testados e utilizados em larga escala com esse intuito. Embora o uso de osso autógeno seja comumente considerado o material de enxerto de primeira escolha, existe uma série de limitações ao seu uso. Nesse trabalho propusemos avaliar o efeito da esponja de chitosan/tricálcio fosfato, que é um bio-polímero natural não tóxico e biodegradável, no reparo de defeitos de tamanho crítico em calvária de ratos. Foram utilizados 20 ratos, machos, adultos, da linhagem Wistar. Confeccionaramse, no osso parietal de cada animal, dois defeitos ósseos de tamanho crítico, com broca trefina de 5mm de diâmetro interno, um dos defeitos recebeu a esponja de chitosan (grupo teste) e o outro foi preenchido com osso autógeno particulado (grupo controle positivo). Após 60 dias, cortes histológicos foram executados observando-se, nos defeitos preenchidos com o chitosan, uma média de 37,79% de remanescentes da esponja. Numa análise linear destes defeitos, o preenchimento ósseo ocorreu numa média de 0,57±0,38mm. Nos defeitos preenchidos com osso autógeno (controle positivo), foi registrada uma média de 5,02mm de osso vital. Comparando os dois grupos experimentais em termos percentuais, observamos que no grupo teste o preenchimento com tecido ósseo foi menor que no grupo controle (7,72% e 68,75%) respectivamente, p<0,001 no teste de Tukey). Dessa forma, conclui-se que a esponja de chitosan/tricálcio fosfato tem um deficiente efeito sobre o reparo ósseo em defeitos de calvária de ratos
Abstract: Periodontology great challenge is to aim the regeneration of periodontal apparatus previously exposed to periodontal disease. Bone substitutes have been extensively tested and used to obtain regeneration. Despite autogenous bone has been considered the gold standard material to perform these techniques there are some restrictions which limit its use. The objective of this study is to evaluate the chitosan/tricalcium phosphate sponge, a non-toxic natural and biodegradable biopolymer, in calvarian defects repair. Twenty adult male Wistar rats were used in this research. Two critical defects were prepared on the parietal bone of each animal using a trephine bur of 5mm inside diameter. One of the defects received chitosan sponge as treatment (test group) and the other was treated with particulate autogenous bone (positive control group). After 60 days the animals were sacrificed and the histological sections were obtained. It was observed in test group a mean remaining chitosan sponge of 37,79%. A linear analysis showed a 0,57±0,38 bone fulfilling mean of the test defects. In defects treated with autogenous bone (positive control group) the mean bone vital observed was 5,02mm. In percentual terms the defect bone fulfilling was less observed in test group rather than control group (7,72% and 68,75% respectively, Tukey test p<0,001). Chitosan/tricalcium phosphate sponge does not improve bone repair in rats calvarian defects
Doutorado
Periodontia
Mestre em Clínica Odontológica
47
Más, Bruna Antunes 1986. "Imobilização de colágeno em arcabouços de poli (L-co-D,L ácido lático)." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/263893.
Full textAbstract:
Orientador: Eliana Aparecida de Rezende DuekDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-18T15:18:31Z (GMT). No. of bitstreams: 1 Mas_BrunaAntunes_M.pdf: 4024365 bytes, checksum: 4922b258d265a9070576f02830e45d40 (MD5) Previous issue date: 2011
Resumo: Polímeros biorreabsorvíveis são amplamente empregados como arcabouços na engenharia tecidual. No entanto, devido à natureza hidrofóbica, técnicas de modificação de superfície embasadas na enxertia de grupos químicos funcionais e imobilização de moléculas bioativas são desenvolvidas no intuito de promover a biofuncionalização da superfície desses polímeros, ocasionando uma melhora significativa da interação célula /polímero. Este estudo teve por objetivo desenvolver e caracterizar uma superfície biomimética em arcabouços do copolímero poli (L-co-D,L ácido lático)- PLDLA, através da enxertia de grupos (-COOH) e imobilização de colágeno tipo I. Os arcabouços de PLDLA 70/30 foram obtidos pela técnica de lixiviação de porógenos e submetidos ao método de fotopolimerização oxidativa da superfície do material, seguido da copolimerização enxertiva do ácido acrílico (PLDLA-AAc) e imobilização do colágeno tipo I (PLDLA-Col). A superfície das amostras foi caracterizada por Microscopia Eletrônica de Varredura (MEV), Microscopia de Força Atômica (MFA), Espectroscopia de Reflectância Total Atenuada (FTIR-ATR), Espectroscopia de Fotoelétrons Excitados por raios-X (XPS) e ângulo de contato. As imagens da MFA e fotomicrografias da MEV demonstraram a formação de poros e rugosidade na superfície dos arcabouços de PLDLA-AAc e, deposição do colágeno com formação de uma estrutura fibrilar em pontos inespecíficos da superfície dos arcabouços do PLDLA-Col, resultando no aumento da rugosidade superficial de 149.5nm (PLDLA puro) para 295nm (PLDLA-Col). Os espectros de FTIR-ATR do PLDLA, PLDLA-AAc e PLDLA-Col confirmaram a presença dos mesmos picos de absorção para todos os tratamentos e, a presença dos picos em 1662 e 1559cm-1, típicos de amida I e II nas amostras de PLDLA-Col. A citocompatibilidade dos arcabouços foi avaliada através do cultivo de células osteoblásticas primárias submetidas aos ensaios de citotoxicidade e adesão celular inicial, síntese de colágeno e observação da morfologia celular, obtidas pela MEV. Os resultados obtidos mostraram que a superfície biomimética dos arcabouços de PLDLA-Col melhora, significantemente, a taxa de adesão e proliferação celular bem como estimula a síntese de colágeno (p<0,01). Estes resultados são indicativos de que o método de modificação de superfície utilizado no presente estudo pode ser usado no desenvolvimento de arcabouços bioativos e biomiméticos com potencial aplicação na engenharia tecidual
Abstract: Bioreabsorbable polymers are widely used as scaffolds in tissue engineering. However, due to their hydrophobic nature, modification techniques based on graft of chemical functional groups and immobilization of bioactive molecules have been developed, in order to promote biofuncionalization of material surface, causing better interaction between cell / polymer. This study aimed at developing and characterizing a biomimetic surface on scaffolds of the copolymer poly (L-co-D, L lactic acid) (PLDLA 70/30), by grafting of chemical functional groups and immobilized with collagen type I. The scaffolds were obtained by porogen leaching, and submitted to photo-oxidation method of the material surface followed by grafting polymer polymerization of the acrylic acid solution (PLDLA-Acc) and immobilization of the type I collagen (PLDLA-Col). The sample surfaces were characterized by Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) , Attenuated Total Reflectance Infrared Spectroscopy (ATR-FTIR), X-ray Photoelectron Spectroscopy (XPS) and contact angle. AFM images and SEM electromicrographs exhibited porous formation and roughness on the PLDLA-AAc surfaces and collagen deposition with net-like fibrillar structure in non-specific areas of the PLDLA-Col scaffolds, resulting an increase in surface roughness from 149.5 nm (PLDLA pure) to 295nm (PLDLA-Col). ATR-FTIR spectra of PLDLA, PLDLA-AAc and PLDLA-Col exhibited the same absorption peaks for all samples, as well as peaks of 1662 and 1559cm-1 , typical of amide I and II in PLDLA-Col samples. Scaffolds cytocompatibilty was evaluated by osteoblastic-like cell culture, submitted to cytotoxicity and initial cell adhesion assays, collagen synthesis and observation of cell morphology obtained by SEM. The result showed that biomimetic surface of PLDLA-Col scaffolds significantly improves adhesion and cell proliferation rates, as well as stimulates collagen synthesis (p<0,01). These results indicate that the surface modification method in the present study can be used in the development of bioactive and biomimetic scaffold with potential application in tissue engineering
Mestrado
Materiais e Processos de Fabricação
Mestre em Engenharia Mecânica
48
Martinelli, Junior Walter. "Estudo histológico dos tecidos conjuntivo e osteóide em enxertos ósseos com polímero de mamona = estudo experimental em ratos." [s.n.], 2011. http://repositorio.unicamp.br/jspui/handle/REPOSIP/308399.
Full textAbstract:
Orientador: Antonio Santos MartinsDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Ciências Médicas
Made available in DSpace on 2018-08-19T12:59:19Z (GMT). No. of bitstreams: 1 MartinelliJunior_Walter_M.pdf: 1045194 bytes, checksum: 4a3f1e71071c89202229ee487def0b2c (MD5) Previous issue date: 2011
Resumo: A reconstrução de defeitos com grande perda óssea representa um desafio para as cirurgias reconstrutivas. Na reconstrução desses defeitos, é preciso criar condições para o estímulo da neoformação, impedindo o crescimento de tecido conjuntivo cicatricial para o interior do defeito ósseo, o que reduz a osteogênese. Para contornar esse problema, utilizam-se os procedimentos de cicatrização óssea guiada, ou aqueles relacionados a enxertia. Contudo, os enxertos quando autógenos têm o inconveniente de submeter o paciente a considerável desconforto e morbidade pós-cirúrgica e, quando homógenos ou xenógenos, podem desenvolver reação de rejeição. Para evitar esses inconvenientes, vem sendo preconizada a utilização de substitutos ósseos sintéticos. O polímero da mamona tem como principais vantagens a disponibilidade e baixo custo (sobretudo por ser de origem nacional), ausência de riscos de transmissão de doenças, ser biotolerável e osseointegrável. O presente estudo teve por objetivo avaliar a evolução e analisar os resultados experimentais em curto prazo, da utilização do polímero da mamona em forma de blocos pré-fabricados, como biomaterial alternativo para utilização nas reconstruções de falhas ósseas. Foram operados 15 ratos machos Wistar SPF albinos adultos, divididos em 3 grupos de 5 animais (grupos G1 , G2 e G3) com período de proservação de 30, 45 e 60 dias respectivamente. Foram criados defeitos nos fêmures dos animais com uma broca esférica de nº 8, removendo parcialmente osso cortical com motor de baixa rotação e abundantemente irrigado com solução salina. Nessa região foram fixados blocos de polímero vegetal (10 x 5 x 1 mm) com parafuso de titânio (1,5 x 8 mm). Após os procedimentos laboratoriais de preparo, as peças foram cortadas e coradas pelo método H.E. Os resultados indicaram biocompatibilidade óssea do polímero vegetal. Em nenhum dos períodos analisados houve reação de rejeição tipo corpo estranho, ocorrendo neoformação de tecido conjuntivo e osteocondróide na interface osso-prótese. Conclui-se, assim, que o polímero vegetal (PV) é um material de enxerto bioativo e osteocondutor, podendo ser considerado um substituto ósseo nacional alternativo facilmente disponível para ser utilizado com sucesso nas cirurgias que envolvem perdas ósseas. Pretendemos prosseguir esse estudo comparando-se a um grupo controle, com follow up maior
Abstract: The reconstruction of great bone loss defects represents a challenge for reconstructive surgery. To reconstruct these defects it is necessary to create conditions to stimulate new bone formation, in order to block the connective healing tissue growth towards the bony defect, which blocks the osteogenesis. The autogenous grafts are inconvenient, because they submit the patient to considerable discomfort and post-operative morbidity. The heterogeneous and xenogenous grafts can also create rejection reaction. This study aimed to evaluate the progress and analyze the experimental results (in the short term), of the use of castor oil polymer in the form of prefabricated blocks, as an alternative biomaterial to reconstruct bone defects. We operated 15 male SPF Wistar albino rats adults, which were divided into 3 groups of 5 animals (groups G1, G2 and G3) with periods of follow up at 30, 45 and 60 days, respectively. Defects were created in the femurs of the animals with a burr, partially removing the cortical bone with low engine speed and abundantly irrigated with saline. In this region were fixed blocks of polymer plant (10 x 5 x 1 mm) with titanium screw (1,5 x 8 mm). After the laboratory procedures of preparation, the samples were counted and stained by HE. The results showed bone biocompatibility of the polymer implant. In none of the periods analyzed we observed inflammatory reaction or reaction foreign body, allowing the neoformation of connective tissue and osteo-chondroid at the bone-prosthesis interface. We conclude that the vegetal polymer is a bioactive and osteoconductive graft and can be considered a national bone substitute alternative, readily available to be successfully used in surgeries that involve bone loss. We intend to continue this study with a comparison to a control group, with longer follow up
Mestrado
Fisiopatologia Cirúrgica
Mestre em Ciências
49
Pereira, Frederico David Alencar de Sena 1983. "Desenvolvimento de um cabeçote para extrusão de filamento fundido aplicado a manufatura aditiva." [s.n.], 2014. http://repositorio.unicamp.br/jspui/handle/REPOSIP/265944.
Full textAbstract:
Orientador: João Maurício RosárioDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica
Made available in DSpace on 2018-08-25T04:55:25Z (GMT). No. of bitstreams: 1 Pereira_FredericoDavidAlencardeSena_M.pdf: 1795891 bytes, checksum: 6d71f97e15d197dbfec6d1fa26bde72a (MD5) Previous issue date: 2014
Resumo: O processo mais difundido de Manufatura Aditiva baseia-se no princípio da deposição de termoplástico fundido e extrudado por um bico. Grande parte dos equipamentos comerciais de Manufatura Aditiva é de projeto fechado e isso dificulta sua aplicação em pesquisas, sobretudo na área de biofabricação, no entanto, outra linha de equipamentos vem surgindo com iniciativa de projetos de código aberto que permitem livremente a sua modificação para aplicações específicas. Este trabalho apresenta o desenvolvimento de um cabeçote para Manufatura Aditiva baseado na extrusão de filamento fundido, que permite o uso de diversos polímeros termoplásticos na máquina de código aberto Fab@CTI. A metodologia do desenvolvimento constituiu de melhorias sucessivas de projetos. A concepção preliminar do cabeçote se deu por meio dos requisitos de usuário e de projeto e outras duas versões foram criadas como conseqüência das melhorias implementadas. Foi dado foco maior na região aquecida a fim de possibilitar o uso do maior número de polímeros possível. O cabeçote desenvolvido permite extrudar materiais termoplásticos com diferentes pontos de fusão e diferentes diâmetros de filamento (1,8 mm à 3,0 mm). Para pesquisa na fabricação de scaffolds, o cabeçote mostrou-se funcional para os polímeros policaprolactona, poli(ácido) lático e polihidroxibutirato, os quais foram estruturados tridimensionalmente com poros a partir de 250 µm e camada mínima de 0,3 mm. A extrusão do acrilonitrila butadieno estireno se mostrou desafiadora e exige maiores investigações embora tenha-se impresso algumas geometrias. Conclui-se que o cabeçote desenvolvido neste trabalho se mostrou funcional, permitindo o processamento de polímeros termoplásticos e estruturar geometrias tridimensionais
Abstract: The most widespread Additive Manufacturing process is based on the principle of deposition of thermoplastic extruded through a nozzle. Much of the commercial Additive Manufacturing equipment are closed project and this complicates its application in research, especially in the field of biomanufacturing, however, a line of equipment with open source projects, allows the free modification for a specific applications. This work shows the development of an Additive Manufacture toolhead based on the fused deposition thermoplastic, which allows the use of various thermoplastics polymers in the open source platform Fab@CTI machine. The development methodology consisted of successive improvements projects. The preliminary design of the toolhead was through the user and design requirements. Two others versions were created as a result of the improvements implemented. Greater focus has been given in the heated region to enable the use of the largest number of polymers as possible. The toolhead developed is able to extrude thermoplastic materials with different melting points and different filament diameters (1.8 mm to 3.0 mm). For the research in scaffolds, the toolhead proved functional for polycaprolactone polymers and polyhydroxybutyrate polylactic acid, which were three dimensionally structured with pore size of 250 micrometers and a minimum of 0,3 mm layer. The extrusion of acrylonitrile butadiene styrene was challenging and requires further investigation although some geometries were printed. It was concluded that the head developed in this study proved to be viable and successfully met its proposal, to process thermoplastic polymers with three-dimensional geometries. Although it was originally developed for the Fab@CTI platform, the system is possible to be adapted to other machines
Mestrado
Mecanica dos Sólidos e Projeto Mecanico
Mestre em Engenharia Mecânica
50
Zainuddin. "Synthesis and calcification of hydrogel biomaterials /." [St. Lucia, Qld.], 2005. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe18693.pdf.
Full text