This diploma thesis is focused on biocompatible polymers degradation study. Copolymers were studied based on poly(lactic-co-glycolic) acid and poly(ethylene glycol) PLGA-PEG-PLGA and further these copolymers modified with itaconic acid ITA-PLGA-PEG-PLGA-ITA. This paper investigated the influence of pH phosphate solution on the degradation of polymers. Degradation of polymers occurred at 37 °C in phosphate solution with pH 4.2, 7.4 and 9.2. High performance liquid chromatography with UV-VIS detection of diode-array type was used for quantitative determination of lactic acid and glycolic acid as the final degradation products. For qualitative identification of additional degradation products were used tandem connection liquid chromatography and mass spectrometry. Gel permeation chromatography with refractive index detector was used to determine the molecular weight decrease polymer chain after the degradation.

Current articular cartilage tissue engineering endeavors, using synthetic polymers as scaffolds, have been somewhat successful. However, the use of these materials has not yielded a satisfactory, functional replacement for articular cartilage. Therefore, this project focuses on an alternative to these materials, chitosan, which is a naturally occurring biopolymer. The first project objective was to fabricate and analyze bulk, porous chitosan scaffolds, based on total porosity, average pore diameter, mechanical integrity, and degradation susceptibility. Secondly, scaffolds were evaluated in terms of their ability to support neochondrogenesis, including assessments of cell attachment and viability, cell morphology, and the biosynthesis of proteoglycan and type-II collagen-rich extracellular matrix. Results indicated that chitosan scaffolds possessing an interconnecting, porous structure could be easily created through a simple freezing and lyophilization process, and these scaffolds did support neochondrogenesis. Results suggest chitosan may be a useful alternative to synthetic polymers for use in cartilage tissue engineering applications.

The first polysulfenamides were synthesized with S-N and N-S-N bonds along the backbone. We demonstrated that sulfenamides were stable in polar protic and aprotic solvents, but degraded rapidly when exposed to acidic conditions. Microparticles were fabricated from polysulfenamides with S-N bonds, their surfaces were readily functionalized, and they were internalized by cells allowing for intracellular delivery of their cargo. These microparticles were also stable at physiological pH, degraded under acidic conditions, and possessed minimal toxicity towards cells. This work demonstrated that polysulfenamides form the basis for a new set of polymers for drug delivery that greatly differ from prior work in this field. New biodegradable polymers with N-S-N bonds along the backbone were synthesized. These were the first polymers with these bonds and possessed many of the same characteristics as polymers synthesized with S-N bonds. The synthesis and characterization of comb block copolymers with arms composed of poly(lactic acid), poly(butyl acrylate), and poly(styrene-b-vinylpyridine) were described. The self-assembled morphologies in the solid state of comb tri- and tetrablock copolymers with poly(styrene) were also described. These assemblies demonstrated that well-ordered and complex morphologies were assembled from these polymers. The steric effect of substitutions on oxanorbornenes in ring opening metathesis polymerization (ROMP) was investigated. Oxanorbornenes substituted with methyls at the bridgehead positions showed limited reactivity with the Grubbs first and second generation catalysts and the Grubbs first generation methylidene catalyst.

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2019-03-25T11:56:58Z No. of bitstreams: 1 Jeferson Cardoso do Rosario_.pdf: 3523684 bytes, checksum: 6d033c623e7ef74a93692efd6ca37e8e (MD5) / Made available in DSpace on 2019-03-25T11:56:58Z (GMT). No. of bitstreams: 1 Jeferson Cardoso do Rosario_.pdf: 3523684 bytes, checksum: 6d033c623e7ef74a93692efd6ca37e8e (MD5) Previous issue date: 2019-01-18 / Nenhuma / O traumatismo cranioencefálico (TCE) é atualmente a terceira maior causa de óbitos no âmbito mundial. Estudos recentes têm demonstrado que a monitorização de pressão intracraniana (PIC), como forma de cálculo da pressão de perfusão cerebral (PPC) é uma ferramenta importante para avaliação do fluxo sanguíneo cerebral (FSC), provocando sensível redução nas taxas de mortalidade. Além do TCE, outras patologias ou situações neurocirúrgicas tem utilizado a técnica de monitorização de PIC. A monitorização desse parâmetro foi proposta já na década de 50, onde um tubo com fluido em contato com o líquido cefalorraquidiano (LCR) era introduzido no espaço intracraniano e conectado a um transdutor de pressão externo. Com a evolução da indústria microeletrônica e dos sistemas microeletromecânicos, foi possível colocar os transdutores na ponta do cateter, permitindo uma monitorização menos invasiva, com menos riscos de infecções. Os cateteres atuais com micro transdutor na ponta podem ser divididos em três grupo: straingauge, fibra óptica e pneumático. Cada grupo possui suas características, entretanto o primeiro tem se demonstrado como solução mais robusta e confiável, com boa relação custo benefício. No presente trabalho foi proposto o desenvolvimento de um cateter implantável de monitorização de pressão intracraniana do tipo micro transdutor strain-gauge. Foram construídos protótipos funcionais e submetidos a ensaios de desempenho, especificados em norma técnica para monitorização de pressão sanguínea, a influência da temperatura na medição de pressão, bem como a exatidão das medições. Os processos empregados no trabalho são utilizados comumente na indústria de encapsulamento de semicondutores, porém foram levadas em consideração as especificidades da aplicação, adequando as técnicas disponíveis às geometrias e materiais empregados, considerando a necessidade de utilização de materiais biocompatíveis. / The traumatic brain injury (TBI) is nowadays the third cause of death in the world. Recent studies have shown the intracranial pressure (ICP) monitoring as an important tool for cerebral perfusion pressure (CPP) calculation and cerebral blood flow (CBF) assestment, reducing significantly the mortality statistics. Besides TBI, several others pathologies and neurosurgery conditions have been using the ICP monitoring technique. The proposal of ICP monitoring first appeared on the 50’s, where a tube fulfilled with fluid in contact with cerebrospinal fluid (CSF) was introduced into the intracranial space and connected to an external pressure transducer. With the waves of the microelectronics and microelectromechanical systems (MEMS) industry evolution, it was possible to put the transducer and all the electronics inside the catheter tip, allowing a less invasive monitoring, decreasing the risk of infection. The state of art catheters with micro transducer on the tip can be divided into three groups: strain-gauge, optical fiber and pneumatic. Each group has it’s own characteristics, however the first has been demonstrated as the rugged solution, being reliable, cost effective and with good accuracy. In the present work, it was proposed the development of an strain-gauge micro transducer implantable catheter for intracranial pressure monitoring. Functional prototypes were built and submitted to performance tests, according to the technical standards in the medical equipment area, the temperature influence over the pressure measurements was evaluated, as well as the accuracy. The adopted processes are commonly used in the semiconductor packaging industry, however it was considered the application special requirements, adapting the processes to the geometry and materials used, considering the needs of biocompatible materials.