Para a produção de compósitos multifuncionais crescente atenção tem sido dada a uma homogeneização eficaz de hidroxiapatitas em matrizes poliméricas, buscando uma sintonia fina da concentração entre polímeros biodegradáveis e biocerâmicas. Este trabalho dedicou-se a síntese, caracterização e estudo das propriedades biológicas do híbrido hidroxiapatita / poli(ε-aprolactona) estrela. A hidroxiapatita nanométrica (HAPN) foi revestida com o polímero biodegradável poli(ε -caprolactona) de topologia em estrela de três braços (PCLE). O uso de um polímero com topologia ramificada visa alterar algumas de suas propriedades mecânicas, a adesão interfacial à cerâmica, a sua viscosidade, o volume hidrodinâmico e sua cinética de degradação. O desempenho do híbrido HAPN/PCLE foi comparado com os materiais: HAP com partículas micrométricas (HAP-91 material comercial), o seu compósito revestido com PCLE (HAP-91/PCLE) e uma cerâmica nanométrica bifásica hidroxiapatita/β-TCP (HAP-8). Os materiais foram caracterizados por avaliações físico-químicas e biológicas realizadas por estudos de citotoxicidade, adsorção de proteínas, proliferação celular, atividade de fosfatase alcalina. A síntese de PCLE foi verificada por análise espectroscópica (espectroscopia no infravermelho-FTIR; ressonância magnética nuclear de prótons- 1H-RMN e carbono- 13C-RMN; a matriz assistida por desorção a laser / ionização; MALDI-TOF; e cromatografia de permeação em gel (GPC). O revestimento das biocerâmicas por PCLE foi confirmado por técnicas de microscopia eletrônica de transmissão (MET) e de varredura (MEV). Os compósitos mostraram uma melhor trababilidade em relação à cerâmica pura e são menos quebradiços, possivelmente devido à presença do PCLE na interface da biocerâmica. A análise de MEV e MET mostrou um aspecto de continuidade no contorno das partículas de cerâmica, em micro e nano-escala. Os compósitos apresentam comportamento não citototóxico e propiciaram um crescimento de células de mamíferos. A proliferação de células osteoblásticas (MG -63) foi significativamente mais elevada para o compósito HAPN/PCLE em comparação com outros biomateriais, sugerindo influência da área de superfície na adesão e proliferação de células. O estudo do ângulo de contato indicou que o revestimento com PCLE faz com que a superfície da biocerâmica seja mais hidrofóbica. O estudo com radioisótopos indicou que o revestimento da biocerâmica com PCLE altera significativamente a adsorção das proteínas do sangue fibrinogênio e albumina. O processo de regeneração do tecido ósseo foi estudado em condições in vivo com a implantação de pastilhas dos materiais estudados em tíbias de coelho. Os resultados mostraram que os compósitos podem ser utilizados como biomaterial, pois houve neoformação óssea ao redor dos implantes. / For the production of multifunctional composites in the combination of biodegradable polymers and bioceramics, increasing attention has been paid to an effective homogenization of hydroxyapatite within polymer matrices and a fine tuning of the concentration. This work was dedicated to the synthesis, characterization and study of the biological properties of the hybrid star poly(ε-caprolactone)/hydroxyapatite composites. A nanometer hydroxyapatite (HAPN) was coated with the biodegradable polymer poly (ε-caprolactone) with three arms star topology (PCLE). The use of polymer branched topology aims to change some of its mechanical properties, the interfacial adhesion to ceramic, its viscosity, the hydrodynamic volume and its degradation kinetics. The performance of the hybrid HAPN/PCLE was compared with the other three materials: HAP commercial micrometric particles (HAP-91), their composite coated with PCLE (HAP-91/PCLE) and a biphasic ceramic nanohydroxyapatite/β-TCP (HAP-8). All materials were characterized by different physico-chemical and biological evaluations performed by cytotoxicity studies, protein adsorption, cell proliferation, alkaline phosphatase activity and an in vivo studies. The synthesis of PCLE was verified by spectroscopic analysis (Fourier-Transform infrared-FTIR and nuclear magnetic resonance-1H-NMR/13C-NMR), matrix-assisted laser desorption/ionization (MALDI-TOF) and gel permeation chromatography (GPC). The coating of the bioceramics by PCLE was confirmed by microscopy techniques transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The composites showed better easy handling in relation to pure ceramic and are less brittle, possibly due to the presence of PCLE at bioceramic interface. The SEM and TEM analysis showed an aspect of continuity in the contour of the ceramic particles, both in micro and nanoscale. The composites exhibit non cytotoxicity behavior and propitiated mammalian cell growth. The proliferation of osteoblastic cells (MG-63) was significantly higher for the composite HAPN/PCLE compared to other biomaterials, suggesting influences of the surface area on the cell adhesion and proliferation. The study of contact angle indicated that the PCLE coating makes the bioceramic surfaces more hydrophobic. The radioisotopic studies indicates that the coating of bioceramics with PCLE significantly alter the adsorption of blood proteins fibrinogen and albumin. The process of regeneration of bone tissue was studied in in vivo conditions after implantation of implants manufactured from composites in rabbit´s tibias. The results showed that composites can be used as biomaterial since the newly bone grew around the implants.

Submitted by Maria Aparecida (cidazen@gmail.com) on 2017-05-30T13:11:14Z No. of bitstreams: 1 Jailton Romão.pdf: 5399205 bytes, checksum: 4addad0621a18f6bf94614b90a8ae4cf (MD5) / Made available in DSpace on 2017-05-30T13:11:14Z (GMT). No. of bitstreams: 1 Jailton Romão.pdf: 5399205 bytes, checksum: 4addad0621a18f6bf94614b90a8ae4cf (MD5) Previous issue date: 2015-07-09 / FAPEMA / The purpose of this study was to synthesize a bioceramic with base of hydroxyapatite and hydroxyapatite by inserting rare earth ions having luminescent properties. Hydroxyapatite (HAP), which is the main mineral that constitutues the bone tissue and represents about 5% of the total mass of an adult person. It is the bioceramic most studied among researchers for medical and dental applications, because they have important properties for biomaterials area, such as: biocompatibility and osteointegration. These properties make it one of the most suitable biomaterials for use in implants, prostheses, among others. The rare earths have luminescent properties with little efficiency when alone, needing a binder matrix (host) to absorb its received radiation energy and transfer the energy to the rare earth ions that, in turn, emit luminescence more intensely. The luminescence of an apatite doped with rare earth is valuable in biological applications such as luminescent markers. The methodology employed was the solid state reaction via calcination involved stoichiometric relationships between the reagents and doping of hydroxyapatite. The dopants were chosen for their fluorescent character and having high possibility of inclusion in the HAP matrix, replacing the Ca2+ ions. The techniques used contributed to verify and compare the formagtion, the structure and crystallinity of the samples. The results obtained from this research were satisfactory when compared with those found in the literature. The analyses of the diffraction of X - rays showed that there was the formation of hydroxyapatite and the dissolution of rare earth ions in the matrix, proven by the Rietveld refinement method. The insertion of the rare earth ions in the hydroxyapatite altered the average size of the crystallite, while increased the concentration of rare earths, the crystallite size decreased. The comparison of the Raman spectra of the doped samples strengthened the idea of the dissolution of the ions in the matrix of the hidoxiapatita demonstrated by fluorescence emission spectrum, because emitted luminescence signals with electronic transitions in the visible spectrum. The figures presented in the density were satisfactory, since they are close to the theoretical values. The increase in density of the samples doped with rare earth ions were also acceptable considering that the TR3+ ions have a higher density than the Ca2+ ions. The values found of the porosity are satisfactory in percentage relations, because the pores are intrinsic characteristics of bioceramic materials and enables adhesion property of the material to the immune tissue. The Fluorescence spectroscopy showed emission signs. Most fluorescence signal intensity occurred in the hydroxyapatite sample doped with europium and ytterbium (HAEu1Yb0,5) enabling its use as a probe or fluorescent marker. The dielectric measurements showed values befitting with the ones found in the literature, as well as the dielectric losses. The conductivity values presented are very low, enabling use of synthesized samples and being used dielectrics. / A finalidade desta pesquisa foi sintetizar e caracterizar uma biocerâmica à base de hidroxiapatita e hidroxiapatita com a inserção de íons terras raras com propriedades luminescentes. A hidroxiapatita (HAP), principal mineral que constitui o tecido ósseo, representa cerca de 5% de massa total de uma pessoa adulta, sendo a biocerâmica mais estudada entre os pesquisadores para aplicações médicas e odontológicas, pois possui propriedades importantes para a área de biomateriais, tais como: biocompatibilidade e osteintegração. Estas propriedades fazem com que seja um dos biomateriais mais adequados para a utilização em implantes, próteses, dentre outras. Os terras raras possuem propriedades luminescentes, com pouca eficiência quando sozinhos, necessitando de uma matriz ligante (hospedeiro) que absorva sua energia de radiação recebida e transfira essa energia para os íons terras raras que, por sua vez, emitem a luminescência de forma mais intensa. A luminescência de uma apatita dopada com terras raras é valorosa em aplicações biológicas, como em marcadores luminescentes. A metodologia empregada foi a reação de estado sólido via calcinação que envolveram relações estequiométricas entre os reagentes e dopagem da hidroxiapatita. Os dopantes foram escolhidos por possuírem caráter fluorescente e por terem grande possibilidade de inserção na matriz da HAP, substituindo os íons Ca2+. As técnicas utilizadas neste trabalho contribuíram para verificar e comparar a formação, a estrutura e cristalinidade das amostras. Os resultados obtidos na realização nesta pesquisa foram satisfatórios quando comparados com os encontrados na literatura. As análises de difração de raios  X mostraram que ocorreu a formação da hidroxiapatita e a dissolução dos íons terras raras na matriz, comprovadas no refinamento pelo Método de Rietveld. A inserção dos íons de terras raras na hidroxiapatita alterou o tamanho médio do cristalito, à medida que aumentava a concentração dos terras raras. A comparação dos espectros Raman das amostras dopadas reforçaram a ideia da dissolução dos íons na matriz da hidroxiapatita comprovada pelo espectro de emissão de fluorescência, pois emitiram sinais de luminescência com transições eletrônicas no espectro visível. Os valores apresentados na densidade foram satisfatórios, pois estão próximos aos valores teóricos. O aumento na densidade das amostras dopadas com íons terras raras também foram aceitáveis, uma vez que possuem densidade maior que íons de Ca2+. Os valores encontrados da porosidade são satisfatórios em relações percentuais, pois os poros são características intrínsecas de materiais biocerâmicos e viabiliza propriedade de adesão do material ao tecido imunológico. A espectroscopia de fluorescência apresentou sinais de emissão, com maior intensidade de sinal ocorrendo na amostra de hidroxiapatita dopada com Európio e itérbio (HAEu1Yb0,5) possibilitando sua utilização como sonda ou marcador fluorescente. As medidas dielétricas mostraram valores condizendo aos encontrados na literatura, assim como as perdas dielétricas. Os valores de condutividade apresentados são muito baixos, possibilitando utilização das amostras sintetizadas como dielétricos.

Nos últimos anos as cerâmicas à base de zircônia, além de outras aplicações, têm sido empregadas em próteses. Isso se deve as suas características como, biocompatibilidade, boa resistência à corrosão e ao desgaste, e tenacidade á fratura. Suas propriedades ópticas permitem reproduzir as características estéticas dos dentes naturais. A resistência da zircônia está relacionada à sua microestrutura, que por sua vez esta relacionada com as características dos pós iniciais. Nesse trabalho foi obtido pó de zircônia estabilizada com ítria pelo processo sol-gel. O tamanho de partículas obtidas foi aproximadamente 2,5 ?m, com zircônia predominantemente na fase tetragonal. O pó foi compactado e sinterizado a 1550°C por 120 minutos. Nestas condições as amostras apresentaram densidade relativa 98%, tamanho médio de grão 0,56 ?m, e predominantemente na fase tetragonal. Foram realizados ensaios em amostras sinterizadas e sinterizadas e tratadas em líquido corpóreo simulado. O módulo de ruptura obtido foi aproximadamente 482 e 560 MPa, a dureza 8,4 e 9,8 GPa e tenacidade á fratura 9,7 e 8,5 MPa.m1/2, para as amostras sinterizadas e sinterizadas e tratadas respectivamente. Também, foi estudado o comportamento à molhabilidade da zircônia sintetizada e sinterizada com água e com fluido corpóreo, mostrando-se excelentes resultados para aplicações biomédicas. Com os resultados obtidos pode-se supor que a zircônia sintetizada é um material promissor para produção de cerâmicas para aplicações biomédicas. / Zirconia based ceramic has been used, besides other applications, in implants due to good strength, good fracture toughness, high wear and corrosion resistance and excellent biocompatility. Its properties permit to reproduce the esthetic characteristics of natural teeth. The zirconia resistance is related with microstructure, that in turn this related with the characteristics of the initials powders. In this work was obtained powder of yttria-stabilized zirconia by sol-gel process. The particles average size 2,5 ?m, in the tetragonal phases. The powders were compacted and sintered at 1550° for 120 minutes. Considering this condition, relative density 98% was reached, the samples presented average grain size 0,56 ?m, and predominantly in the tetragonal phases. Sintered samples and sintered and treated in the simulated body fluid were tested. The flexural strength obtained were 482 and 560 MPa, the hardness 8,4 and 9,8 GPa and fracture toughness 9,7 e 8,5 MPa.m1/2, for sintered samples and sintered and treated respectively. Also, was studied the wetability behavior of the sintered zirconia with water and simulated fluid, showing excellent results for biocompatibility application. With obtained results can be supposed the sintetized zirconia is promissory material to biomedical applications.

Neste trabalho, a resistência à corrosão in vitro da liga de titânio Ti-13Nb-13Zr, fabricada em laboratório nacional, e destinada a aplicações ortopédicas, foi investigada em soluções que simulam os fluidos corpóreos. Os eletrólitos usados foram solução 0,9 % (massa) de NaCl, solução de Hanks, meio de cultura (MEM), neste dois últimos meios, sem e com adição de peróxido de hidrogênio. A adição de peróxido visou simular condições existentes em caso de processos inflamatórios resultantes de procedimentos cirúrgicos. A resistência à corrosão de ligas já comercialmente consagradas para uso como biomateriais, Ti-6Al-7Nb e Ti-6Al-4V, bem como do titânio puro (Ti-cp), foi também estudada por razões de comparação com a liga Ti-13Nb-13Zr. Foram utilizadas técnicas eletroquímicas e de análise de superfície. As técnicas eletroquímicas consistiram de: (a) medidas da variação do potencial a circuito aberto em função do tempo, (b) polarização potenciodinâmica e (c) espectroscopia de impedância eletroquímica (EIE). Os diagramas experimentais de impedância foram interpretados utilizando circuitos elétricos equivalentes que simulam modelos de filme óxido de estrutura dupla composta de uma camada interna compacta, tipo barreira, e uma camada porosa mais externa. Os resultados mostraram que a resistência à corrosão deve-se principalmente à camada barreira, e indicaram alta resistência à corrosão de todas as ligas e do Ti-cp em todos os meios estudados. O óxido formado na superfície da liga Ti-13Nb-13Zr, seja naturalmente ou em meios fisiológicos, foi caracterizado utilizando espectroscopia de fotoelétrons excitados por raios-X (XPS) e microscopia eletrônica de varredura (MEV). Os resultados mostraram que a presença de peróxido de hidrogênio em MEM promove o crescimento da camada porosa e incorporação de íons minerais, além de favorecer a formação de hidroxiapatita. A citotoxicidade da liga Ti-13Nb-13Zr foi também avaliada e esta se mostrou ser não tóxica. / In this work, the in vitro corrosion resistance of the Ti-13Nb-13Zr alloy, manufactured at a national laboratory, and used for orthopedic applications, has been investigated in solutions that simulate the body fluids. The electrolytes used were 0.9 % (mass) NaCl, Hanks\' solution, a culture medium (MEM), and the two last electrolytes, without and with addition of hydrogen peroxide. The aim of peroxide addition was to simulate the conditions found when inflammatory reactions occur due to surgical procedures. The corrosion resistance of alloys commercially in use as biomaterials, Ti-6Al-7Nb and Ti-6Al-4V, as well as of the pure titanium (Ti-cp), was also studied for comparison with the Ti-13Nb-13Zr alloy. The corrosion resistance characterization was carried out by electrochemical and surface analysis techniques. The electrochemical tests used were: (a) open circuit potential measurements as a function of time, (b) potentiodynamic polarization and (c) electrochemical impedance spectroscopy (EIE). The impedance experimental diagrams were interpreted using equivalent electric circuits that simulate an oxide film with a duplex structure composed of an internal and compact, barrier type layer, and an external porous layer. The results showed that the corrosion resistance is due mainly to the barrier type layer. The titanium alloys and the Ti-cp showed high corrosion resistance in all electrolytes used. The oxides formed on the Ti-13Nb-13Zr, either naturally or during immersion in MEM or Hanks’ solution was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (MEV). The results showed that the presence of hydrogen peroxide in MEM promotes the growth of the porous layer and incorporation of mineral ions, besides favouring hydroxyapatite formation. The citotoxicity of the Ti-13Nb-13Zr alloy was also evaluated and it was shown to be non-toxic.

Biomateriais para uso em implantes devem exibir propriedades como biocompatibilidade, biofuncionalidade e resistência à corrosão. O uso do titânio e suas ligas em aplicações biomédicas vem continuamente aumentando devido à sua maior taxa resistência-peso, superior biocompatibilidade e resistência à corrosão, boas propriedades mecânicas e baixo módulo de elasticidade quando comparado a outros materiais biomateriais metálicos como aço inox e ligas Co-Cr. Um importante aspecto para o sucesso de um implante é a utilização de materiais com módulo de elasticidade baixo, próximo ao do osso, pois estudos indicam que a transferência insuficiente de carga entre implante e osso pode resultar em reabsorção óssea e afrouxamento do implante, que é chamado efeito de blindagem de tensão (stress shielding effect). A liga ternária Ti13Nb13Zr apresenta em sua composição somente elementos considerados biocompatíveis, possui menor módulo de elasticidade que ligas Co-Cr, aço inox e Ti6Al4V, e superior resistência à corrosão. Neste trabalho foi estudado o efeito do teor de nióbio e zircônio nas propriedades mecânicas da liga ternária TiNbZr numa faixa de composições com quantidade de titânio constante em 74 %peso e teor de Nb e Zr variando entre 6 e 20 %peso, produzida por metalurgia do pó a partir de pós hidrogenados e método de mistura elementar, após diferentes condições de processamento e tratamentos térmicos. Os resultados de caracterização microestrutural obtidos por MEV e difração de raios X mostraram que o aumento do teor de Nb não produziu alterações significativas na fração volumétrica das fases e e, o aumento do teor de Zr proporcionou o aumento da fração de fase , favorecendo a formação da estrutura de Widmanstätten. O aumento dos teores de Nb e Zr produziram alterações nas microestruturas dos materiais que levaram ao aumento dos valores de módulo de elasticidade e dureza, e com aumento do teor de Zr houve aumento da susceptibilidade à corrosão. Nas condições de processamento utilizadas, a liga Ti13Nb13Zr apresentou as propriedades mecânicas e microestruturais mais indicadas para utilização como biomateriais. / Biomaterials for use in implants must be biocompatible, biofunctional and resistant to corrosion. Utilization of titanium and its alloys is continuously increasing due to their larger strength-weight ratio, superior biocompatibility e corrosion resistance, good mechanical properties and low elastic modulus when compared to other metallic biomaterials such as stainless steel and Co-Cr alloys. Using materials with low elastic modulus, close to bone values, is important to reduce stress shielding effect, which can cause implant loosening. Ti13Nb13Zr ternary alloy shows only elements considered biocompatible and has a lower elastic modulus than Co-Cr alloy, stainless steel and Ti6Al4V, and superior corrosion resistance. In this work TiNbZr alloy was prepared in different compositions, maintaining Ti content at 74%wt with Nb and Zr contents ranging amongst 6 and 20%wt, produced by powder metallurgy using different processing conditions and heat treatments. Characterization via SEM and X-Ray diffraction showed that the Nb increase didnt produce significant alterations on volume fraction of and phases in the material, and the increase in Zr content led to an increase in phase amounts and formation of Widmanstätten patterns. Nb and Zr content increasing produced microstructural modifications, leading to an increase in elastic modulus and hardness values, as well as corrosion susceptibility variations, where higher Zr contents leaded to a surface with less corrosion resistance. Amongst compositions and for the designed processing method, Ti13Nb13Zr presented the most indicated mechanical and microstructural properties for utilization as biomaterials.

Gene therapy is an approach for the treatment of acquired cancers, infectious disease, degenerative disease, and inherited genetic indications. Developments in the fields of immunotherapies and CRISPR/Cas9 genome editing are revitalizing the efforts to move gene therapy to the forefront of modern medicine. However, slow progress and poor clinical outcomes have plagued the field due to regulatory and safety concerns associated with the flagship delivery vector, the recombinant virus. Immunogenicity and poor transduction in certain cell types severely limits the utility of viruses as a delivery agent of nucleic acids. As a result, significant efforts are being made to develop non-viral delivery systems that perform mechanistically similarly to viral delivery but lack immunogenic factors. Though safer, existing agents lack the efficacy inherent in the natural design of viral vectors. Clinical relevance of non-viral vectors will therefore depend on the ability to engineer optimized systems for cellular delivery in physiological environments. Progress in non-viral vector design for gene delivery requires a deep understanding of the various barriers associated with nucleic acid delivery, including cell surface interaction, internalization, endosomal escape, cytosolic transport, nuclear localization, unpackaging, etc. Further, it requires a knowledge of vector design properties (surface chemistry, charge, size, shape, etc.) and how these physical parameters affect interactions with the cellular environment. Of these interactions, charge is shown to govern how particles are internalized and subsequently processed, thereby affecting the intracellular fate and efficacy of delivery. Charge also affects the in-serum stability where negative zeta potential improves stability and circulation time. Therefore, it is important to understand the effects of polyplex charge and other parameters on the internalization and intracellular fate of polyplexes for gene therapy. In chapter 2, studies are performed to delineate the effects of polyplex charge on the cellular internalization and intracellular processing of polymer-mediated gene delivery. Charge is shown to affect the endocytic pathway involved in internalization, and the caveolin-dependent and macropinocytosis pathways lead to higher gene delivery efficacy, likely due to avoidance of acidified compartments such as late endosomes and lysosomes. In chapters 3-4, novel nanoparticles carrying DNA, RNA, and antioxidants are assessed for therapeutic effect with an emphasis on studying the internalization mechanisms and resulting effect on efficacy. Novel RNA delivery agents are shown to benefit from EGFR-targeting aptamer and nanoceria/PEI hybrids are demonstrated to provide simultaneous antioxidant and gene therapy. Finally, chapter 5 demonstrates the use of silencing RNA and CRISPR/Cas9 genome editing to study the prevalence of gene targets in vivo. The overall goal of this work is to contribute to the design and application of novel nanoparticles for gene delivery and offer insight into the engineering of novel polyplexes. It remains clear that route of internalization is key to successful gene delivery, and designing polyplexes to enter through non-acidified endocytic pathways is highly beneficial to transgene expression. This can be achieved through incorporation of surface chemistries that trigger internalization through targeted pathways and is the source of further work in the lab.

<p>Peptides are a fundamental building-block of living systems and play crucial roles at both functional and structural level. Therefore, they have attracted increased attention as a platform to design and engineer new self-assembled systems that span the nano-to-meso scales. The rules of peptide design and folding enable the construction of suitable building-blocks to develop soft materials for biomaterial applications. Herein we present the use of the alpha-helical secondary structure to create two distinct structural motifs, namely coiled-coils and helical bundles. These peptide components can differ in size and incorporate a host of different functional moieties, the effects of which are described through their hierarchical assembly. </p> <p>First, we describe the self-assembly of coiled coil oligomers (trimer and tetramer) of the GCN4 leucine zipper peptide. The trimeric coiled coil was modified with varying number of aromatic groups (one to three) along each helical backbone, to facilitate higher order assemblies into banded nano- to micron-sized structures, the formation of which could be controlled reversibly as a function of pH. In addition, the electrostatic and aromatic interactions of the peptide material were harnessed for non-covalent binding of small drug molecules, followed by their subsequent pH-triggered release. Furthermore, these nanostructures are compatible with MCF-7 breast cancer cells, making them suitable drug-delivery agents for chemotherapeutics. In the absence of aromatic modifications, the coiled-coil trimer assembles into higher-order nanotubes that can be harnessed for selective encapsulation of high molecular weight biomolecules. With an increase in oligomerization from three to four, along with a single aromatic group modification on each helix, the tetrameric coiled-coil mutant successfully demonstrates a metal-assisted two-tier structural assembly into microbarrels and spheres.</p> <p>Second, we present the higher-order assembly of short tetrameric and pentameric helical bundle proteins, covalently stabilized by a belt of disulfide bridges, with metal-binding ligands at each helix termini. The addition of metals like Zn(II) and Cu(II) promote the assembly of the bundles into a 3D globular matrix, which upon thermal annealing transforms into microspheres. Additionally, these microspheres also demonstrate the metal-assisted inclusion of His-tagged fluorophores. Thus, peptide-based materials can be constructed by self-assembly of alpha-helical building blocks into systems with sophisticated, diverse morphologies and dynamic chemical properties, that can be further modulated to enhance performance for medical applications. </p>

In 2005, over 200,000 Americans underwent a hip arthroplasty, the replacement of a hip joint with an artificial prosthesis. Of these arthroplasties, metal-on-metal type implants represent an increasing usage percentage. Metal-on-metal implants are selected largely for their low volumetric wear rate, durability, and resistance to corrosion. In spite of these advantages, little is known concerning the long-term consequences of heavy metal alloy use in the body, although early research indicates potentially carcinogenic results. This thesis is a preliminary investigation into these long term effects and their root causes. An improved comprehension of the corrosion kinetics and the rate of ion production from the high surface energy wear debris released by implant articulation can assist in illustrating the relative clinical significance of exposure to these metallic bodies over time. This thesis primarily focuses on developing a test methodology for the detection and analysis of ion dissociation in simulated body fluids. In order to validate this test methodology, the ion dissociation rates and surface characteristics of several predetermined diameters of cobalt chromium alloy spherical particles were analyzed. The effect of changing particle diameter, and thus surface area to volume ratio, on ion dissociation rate was determined to be significant when not affected by localized agglomeration. Additionally, preferential corrosion of cobalt within individual grains was observed and correlated to elevated cobalt concentrations in the electrolyte. These results suggest that ion dissociation kinetics for true wear particles can be determined through the refinement and application of the methodology developed.

Chronic Obstructive Pulmonary Disease (COPD) is a leading cause of death worldwide. Alveolar wall destruction is a significant contributor to COPD. Inflammatory macrophages are a major source of the Extracellular Matrix (ECM) proteolysis. ECM breakdown causes air to get trapped in the alveoli, obstructing airflow. One step in curing COPD may be to convert inflammatory to pro-regenerative macrophages. Recently, decellularized ECM scaffolds have shown the ability to induce a pro-regenerative phenotype. Yet these scaffolds are incapable for reaching the alveolar region of the lungs. To reach the alveolar region particles need a diameter of 1-5 μm or smaller than 300 nm. We used protein from decellularized lung tissue to create nanoparticles. By first digesting the protein in acid, we electrosprayed the solution into nanoparticles. The average size of the nanoparticles is 225 (± 67) nm, within the requirements to reach alveoli. However, another barrier exists for treating this disease. That barrier is mucus; mucus hypersecretion is another sign of COPD. The formed particles are capable of penetrating the mucus layer in COPD. After characterizing the particles, we began in vitro investigations. First, we measured cytotoxicity of the nanoparticles. In alveolar epithelial cells, adding nanoparticles to the media increased cellular proliferation. We then added the nanoparticles to isolated murine macrophages. The nanoparticles induced a pro-regenerative phenotypic shift in murine macrophages. These experiments reveal that these nanoparticles may become an effective treatment for degenerative lungs diseases, such as COPD, after further investigation.

In cases of compromised bone remodeling like osteoporosis, insufficient osseointegration occurs and results in implant failure. Implant retention relies on proper secondary fixation, which is developed during bone remodeling. This process is disrupted in metastatic bone diseases like osteoporosis. Osteoporosis is characterized low bone mass and bone strength resulting from either accelerated osteoclast-mediated bone resorption or impaired osteoblast-mediated bone formation. These two processes are not independent phenomena. In fact, osteoporosis can be viewed as a breakdown of the cellular communication connecting bone resorption to bone formation. Because bone remodeling occurs at temporally generated specific anatomical sites and at different times, local regulators that control cross-talk among the cells of the BRU are important. Previous studies show Ti implant surface characteristics like roughness, hydrophilicity, and chemistry influence the osteoblastic differentiation of human MSCs and maturation of OBs. Furthermore, microstructured Ti surfaces modulate the production of factors shown to be important in the reciprocal communication necessary for the maintenance of healthy bone remodeling. Semaphorin signaling proteins are known to couple the communication of osteoblasts to osteoclasts and are capable of stimulating bone formation or bone resorption depending on certain cues. Implant surface properties can be optimized to exploit these effects to favor rapid osseointegration in patients with osteoporosis.