PLGA have already been successfully applied for controlled drug delivery systems by the pharmaceutical industry due to its biocompatibility, biodegradability and ease of processing. It has recently further been developed and formulated into a form of nanoparticle. The single emulsion evaporation method was used to prepare nanoparticles in this study. By varying different parameters such as the concentration of regents, the type of surfactant and emulsion method, different particle sizes and size distribution of PLGA nanoparticles could be obtained. The stability of PLGA nanoparticles was further investigated by assessing their thermal property over a certain period of time using DSC. The decrease of Tg confirmed the hydration and degradation of PLGA polymers and nanoparticles. The changes of surface morphology showed that the nanoparticles were in spherical shape and maintained smooth surface before the storage, whereas they started to lose their original shapes as well as agglomerate to each other after 2-week storage. These results suggested that there was an erosion and degradation of PLGA nanoparticles during storage. Ibuprofen-loaded PLGA nanoparticles have been successfully prepared by o/w single emulsion evaporation method. During the stability study, a faster degradation rate compared to non-loaded PLGA nanoparticles was exhibited, showing that Ibuprofen increased the degradation rate of PLGA nanoparticles. According to the results of drug releasing study, PLGA nanoparticles exhibiting a slower drug release rate than pure drug which proved that drug-nanoparticule system could effectively increase the stability of drugs. PLGA polymer is a potential material for drug delivery system.

Introduction: Bone defects and non-unions caused by trauma, tumor resection, pathological degeneration, or congenital deformity pose a great challenge in the field of orthopedics. Traditionally, these defects have been repaired by using autografts and allografts. Autografts have set the gold standard for clinical bone repair because of their osteoconductivity, osteoinductivity and osteogenicity. Nevertheless, the application of autografts is limited because of donor availability and donor site morbidity. Allografts have the advantage that the tissues are readily available and can be easily applied, especially when large segments of bone are to be reconstructed. However, their use is also limited by the risk of disease transfer and immune rejection. To circumvent these limitations tissue engineering has evolved as a means to develop viable bone grafts. An ideal bone graft should be both osteoconductive and osteoinductive, biomechanically strong, minimally antigenic, and eliminates donor site morbidity and quantity issues. The biodegradable polymer, Poly lactic-co-glycolic acid (PLAGA) was chosen because of its commercial availability, biocompatibility, non-immunogenicity, controlled degradation rate, and its ability to promote optimal cell growth. To improve the mechanical properties of PLAGA, Single Walled Carbon Nanotubes (SWCNT) were used as a reinforcing material to fabricate composite scaffolds. The overall goal of this project is to develop a Single Walled Carbon Nanotube composite (SWCNT/PLAGA) for bone regeneration and to examine the interaction of MC3T3-E1 cells (mouse fibroblasts) and hBMSCs (human bone marrow derived stem cells) with the SWCNT/PLAGA composite via focusing on extracellular matrix production and mineralization; and to evaluate its toxicity and bio-compatibility in-vivo in a rat subcutaneous implant model. We hypothesize that reinforcement of PLAGA with SWCNT to fabricate SWCNT/PLAGA composites increases both the mechanical strength of the composites as well as the cell proliferation rate on the surface of the composites while expressing osteoblasts phenotypic, differentiation and mineralization markers; and SWCNT/PLAGA composites are biocompatible and non-toxic, and are ideal candidates for bone tissue engineering. Methods: PLAGA and SWCNT/PLAGA composites were fabricated with various amounts of SWCNT (5, 10, 20, 40 and 100mg), characterized and degradation studies were performed. PLAGA (poly lactic-co-glycolic acid) and SWCNT/PLAGA microspheres and composites were fabricated; characterized and mechanical testing was performed. Cells were seeded and cell adhesion/morphology, growth/survival, proliferation and gene expression analysis were performed to evaluate biocompatibility. Sprague-Dawley rats were implanted subcutaneously with Sham, poly lactic-co-glycolic acid (PLAGA) and SWCNT/PLAGA composites, and sacrificed at 2, 4, 8 and 12 week post-implantation. The animals were observed for signs of morbidity, overt toxicity, weight gain, food consumption, hematological and urinalysis parameters, and histopathology. Results: Imaging studies demonstrated uniform incorporation of SWCNT into the PLAGA matrix and addition of SWCNT did not affect the degradation rate. Composites with 10mg SWCNT resulted in highest rate of cell proliferation (p<0.05) among all composites. Imaging studies demonstrated microspheres with uniform shape and smooth surfaces, and uniform incorporation of SWCNT into PLAGA matrix. The microspheres bonded in a random packing manner while maintaining spacing, thus resembling trabeculae of cancellous bone. Addition of 10mg SWCNT led to greater compressive modulus and ultimate compressive strength. Imaging studies revealed that MC3T3-E1 cells adhered, grew/survived, and exhibited normal, non-stressed morphology on the composites. SWCNT/PLAGA composites exhibited higher cell proliferation rate and gene expression compared to PLAGA. No mortality and clinical signs were observed. All the groups showed consistent weight gain and rate-of-gain for each group was similar. All the groups exhibited similar pattern for food consumption. No difference in urinalysis parameters, hematological parameters; and absolute and relative organ weight was observed. A mild to moderate summary toxicity (sumtox) score was observed for animals treated with the PLAGA and SWCNT/PLAGA whereas the sham animals did not show any response. At all the time intervals both PLAGA and SWCNT/PLAGA showed a significantly higher sumtox score compared to the Sham group. However, there was no significant difference between PLAGA and SWCNT/PLAGA groups. Conclusion: Our SWCNT/PLAGA composites, which possess high mechanical strength and mimic the microstructure of human trabecular bone, displayed tissue compatibility similar to PLAGA, a well known biocompatible polymer over the 12 week study. Thus, the results obtained demonstrate the potential of SWCNT/PLAGA composites for application in BTE and musculoskeletal regeneration. Future studies will be designed to evaluate the efficacy of SWCNT/PLAGA composites in bone regeneration in a non-union ulnar bone defect rabbit model. As interest in carbon nanotube technology increases, studies must be performed to fully evaluate these novel materials at a nonclinical level to assess their safety. The ability to produce composites capable of promoting bone growth will have a significant impact on tissue regeneration and will allow greater functional recovery in injured patients.

Submitted by isabela.moljf@hotmail.com (isabela.moljf@hotmail.com) on 2017-05-18T13:38:03Z No. of bitstreams: 1 soniamariacruzbastos.pdf: 1103097 bytes, checksum: cd7a339f9e0634c2bfe4c60f01ce3a45 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-05-18T14:07:57Z (GMT) No. of bitstreams: 1 soniamariacruzbastos.pdf: 1103097 bytes, checksum: cd7a339f9e0634c2bfe4c60f01ce3a45 (MD5) / Made available in DSpace on 2017-05-18T14:07:57Z (GMT). No. of bitstreams: 1 soniamariacruzbastos.pdf: 1103097 bytes, checksum: cd7a339f9e0634c2bfe4c60f01ce3a45 (MD5) Previous issue date: 2012-12-11 / Ceratoses Actínicas (CA) são lesões de pele frequentes, induzidas primariamente pela luz ultravioleta e que surgem preferencialmente na superfície da pele foto exposta. Representam a manifestação inicial da proliferação de ceratinócitos atípicos intra-epiteliais com um potencial de 0,25% e 20% ao ano de evoluir para o carcinoma espinocelular (CEC) que é metastatizante. São diagnosticadas clinicamente e tratadas ambulatorialmente. Prevalência mundial, com maior distribuição em indivíduos de pele clara fototipo I e II de Fitzpatrick. Existem vários tratamentos (tópicos, cirúrgicos e sistêmicos), sendo a prevenção a modalidade mais importante. O ácido glicólico, primeiro de uma série de alfa hidroxiácidos, quando aplicado topicamente, em baixas concentrações (2% a 12%) nos veículos, cremes, géis ou loções não iônicas, age como epidermolítico e ceratolítico. Isto o torna um excelente ativo no tratamento que propomos. Nosso objetivo foi pesquisar a efetividade ou não de uma nova conduta terapêutica para CA. Avaliar a adesão do paciente ao tratamento. Observar a apresentação de efeitos adversos indesejáveis. O Estudo foi Clínico, Prospectivo, Transversal em pacientes atendidos no Ambulatório de Dermatologia Geriátrica do HU/CAS da UFJF, total de 50 indivíduos. Todos portadores de ceratoses actínicas na face. O resultado mostra que a resolução total das CA não foi observada em todos os pacientes, mas houve adesão completa ao medicamento, não sendo observados efeitos adversos na população em estudo. Concluímos que mesmo não sendo completamente eficaz para o desaparecimento das lesões levou a uma diminuição acentuada do número de lesões e do índice de gravidade das mesmas. / Actinic keratoses (AK) are common skin lesions, primarily induced by ultraviolet light, occurring mainly on the photoexposed skin surface. They represent the initial manifestation of proliferation of atypical intraepithelial keratinocytes with a potential of 0.25% - 20% per year progress to squamous cell carcinoma (SCC), which is metastasizing. They are clinically diagnosed and treated on an outpatient basis. They are prevalent worldwide, with higher distribution in light-skinned individuals of Fitzpatrick phototype I and II. There are several treatments (topical, surgical and systemic), prevention being the most important modality. Glycolic acid, the first of a series of alpha hydroxyacids, when applied topically in low concentrations (2% to 12%) in cream, gels or nonionic lotions, acts as an epidermolytic and keratolytic. This makes it an excellent asset in the treatment that we propose. Our objective was to investigate the effectiveness or otherwise of a new therapeutic approach to AK, assess patient adherence to treatment and observe the appearance of adverse reactions. The study was clinical, prospective, transversal in patients seen at the Geriatric Dermatology Clinic of HU / CAS UFJF, 50 individuals altogether. All patients had actinic keratoses on their face. The result show that total resolution of AK was not observed in all patients, but there was complete adherence to medication, adverse effects not being observed in the study population. We conclude that, although not completely effective for the disappearance of the lesions, it led to a marked decrease in the number of lesions and the severity index of these.

Tobacco smoking has consistently been the leading cause of preventable diseases and premature deaths. Currently, pharmacological interventions have only shown limited smoking cessation efficacy and sometimes are associated with severe side effects. As an alternative, nicotine vaccines have emerged as a promising strategy to combating nicotine addiction. However, conventional conjugate nicotine vaccines have shown limited ability to induce a sufficiently strong immune response due to their intrinsic shortfalls. In this study, a lipid-poly(lactic-co-glycolic acid) (PLGA) nanoparticle-based next-generation nicotine vaccine has been developed to overcome the drawbacks of conjugate nicotine vaccines. Also, the influence of multiple factors, including nanoparticle size, hapten density, hapten localization, carrier protein, and molecular adjuvants, on its immunogenicity has been investigated. Results indicated that all these studied factors significantly affected the immunological efficacy of the nicotine nanovaccine. First, 100 nm nanovaccine was found to elicit a significantly higher anti-nicotine antibody titer than the 500 nm nanovaccine. Secondly, the high-density nanovaccine exhibited a better immunological efficacy than the low- and medium-density counterparts. Thirdly, the nanovaccine with hapten localized on both carrier protein and nanoparticle surface induced a significantly higher anti-nicotine antibody titer and had a considerably better ability to block nicotine from entering the brain of mice than the nanovaccines with hapten localized only on carrier protein or nanoparticle surface. Fourthly, the nanovaccines carrying cross reactive materials 197 (CRM197) or tetanus toxoid (TT) showed a better immunological efficacy than the nanovaccines using keyhole limpet hemocyanin (KLH) or KLH subunit as carrier proteins. Finally, the co-delivery of monophosphoryl lipid A (MPLA) and Resiquimod (R848) achieved a considerably higher antibody titer and brain nicotine reduction than only using MPLA or R848 alone as adjuvants. Collectively, the findings from this study may lead to a better understanding of the impact of multiple factors on the immunological efficacy of the hybrid nanoparticle-based nicotine nanovaccine. The findings may also provide significant guidance for the development of other drug abuse and nanoparticle-based vaccines. In addition, the optimized lipid-PLGA hybrid nanoparticle-based nicotine nanovaccine obtained by modulating the studied factors can be a promising candidate as the next-generation nicotine vaccine for treating nicotine addiction. / PHD

Dexamethasone and dexamethasone 21-phosphate were loaded into NDGA-polymerized collagen fibers and release rate studies were performed to calculate their diffusion coefficients. Dexamethasone loaded fibers were placed in a PBS solution for specified time intervals (1, 3, 6, 7, 12, 24, 30, and 48 hours) after which the eluant was removed and analyzed by capillary zone electrophoresis (CZE). CZE is a tool that can be utilized for quantitative analysis of chemical compounds. This data was incorporated into mathematical models to determine the diffusion coefficient. The diffusion coefficient (D) for dexamethasone in NDGA-polymerized collagen fibers is D = 1.86 x 10⁻¹⁴ m²/s. Similarly, dexamethasone 21-phosphate loaded fibers were placed into a PBS solution and analyzed using CZE at these specified intervals (15, 30, 45, 60, and 75 minutes). Applying this data to the mathematical model provided a diffusion coefficient for dexamethasone 21-phosphate in NDGA-polymerized collagen fibers of D = 2.36 x 10⁻¹³ m²/s. In an effort to control drug delivery from these fibers a polylactic-co-glycolic acid (PLGA) coating was applied to the fibers. This coating helped sustain delivery of dexamethasone 21-phosphate for over a 100 day period. CZE experiments were again conducted in conjunction with another mathematical model to characterize release. A semi steady-state diffusion coefficient was estimated to be D = 4.59 x 10⁻¹⁴ m²/s.

Made available in DSpace on 2014-10-09T12:41:36Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:54Z (GMT). No. of bitstreams: 0 / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Made available in DSpace on 2014-10-09T12:41:36Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:08:54Z (GMT). No. of bitstreams: 0 / A Organização Mundial da Saúde (OMS) relata o câncer como uma das principais causas de morte no mundo. O câncer de próstata é o segundo tipo de câncer mais prevalente em homens. Uma modalidade de tratamento que vem sendo bastante utilizada é a braquiterapia, que consiste na introdução de sementes com material radioativo no interior do orgão. Sementes de Iodo-125 podem ser inseridas soltas ou em cordas poliméricas bioabsorvíveis. As sementes em cordas poliméricas apresentam algumas vantagens, pois reduzem a taxa de migração das sementes, evento que poderia afetar a dosimetria da região e causar danos desnecessários a tecidos ou órgãos sadios. Para as sementes de Iodo-125 em cordas poliméricas, utiliza-se a poliglactina 910, (poli(ácido lático-co-ácido glicólico)) (PLGA), com cobertura de poliglactina 370 (Vicryl®). Foi proposto neste trabalho, o estudo e desenvolvimento da metodologia de síntese do biopolímero PLGA, via polimerização por abertura de anéis, assim como sua caracterização, com o propósito de utilizar o material sintetizado para fabricar um material similar ao RAPID-Strand®. Os resultados obtidos demonstram que, através da metodologia utilizada, foi possível determinar os melhores parâmetros de reação (tempo e temperatura) para o PLGA na proporção 80/20 (lactídeo/glicolídeo). Com uma temperatura de 110ºC e tempo de reação de 24h, foi possível obter 86% de rendimento, e com o aumento o tempo de reação para 72h, o rendimento é superior a 90%. Os valores de massas moleculares obtidas entre os testes, ainda são muito baixos quando comparados com os valores obtidos por outros autores na literatura (cerca de 20%). Falhas na selagem das ampolas, deixando-os vulneráveis à umidade e oxigênio, ou a falta de uma sistema eficiente de agitação podem ser possíveis explicações para estes resultados. Um reator químico adequado poderia solucionar o problema. Em relação à caracterização, as técnicas utilizadas confirmaram a estrutura esperada do polímero, e a maior proporção das unidades provenientes do dímero lactídeo, em relação ao glicolídeo. / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Capsaicin, prostaglandin E2 (PGE2) and polydopamine (PDA) were used to target macrophage and myofibroblast activity to reduce biomaterial-induced fibrosis. The lifetime and efficacy of implantable biomedical devices are determined by the foreign body response. Immediately after implantation, proteins nonspecifically adsorb onto the material and initiate inflammation. Macrophages recruited to the site can differentiate into M1 and M2 phenotypes and upregulate inflammation and fibrosis which interferes with the intended function. M1 macrophages secrete pro-inflammatory mediators that induce chronic inflammation and promote myofibroblast differentiation while M2 macrophages are wound healing cells that suppress inflammation and regulate fibroblast activity. The fibrotic tissue is developed by myofibroblasts which produce collagen in an unregulated fashion. Collagen thickening and biomaterial encapsulation decreases efficacy and sensitive of biomedical devices. We investigated the in vitro and in vivo effects of capsaicin, PGE2 and polydopamine surface modification on macrophages and myofibroblasts. Capsaicin and PGE2 reduced poly(lactic-co-glycolic) acid (PLGA)-induced fibrosis by promoting M2 macrophage phenotype to secrete anti-inflammatory IL-10 and suppressing myofibroblast marker α-smooth muscle actin (α-SMA). Capsaicin decreased collagen by 40% and upregulated IL-10 secretion by 35% while PGE2 reduced collagen by 55% after 14 days of implantation and 40% less collagen after 42 days. PDA was used to bind an anti-fibrotic compound to the surface of a poly(dimethyl siloxane) (PDMS-PDA) to reduce fibrosis. However, PDMS-PDA controls gave an unexpected result by reducing fibrosis to the same extent as anti-fibrotic compound bound PDMS- v PDA. PDA modification reduced cellularity by 50% and significantly decreased collagen thickness by 30%. Overall, our results showed that biomaterial-induced fibrosis can be reduced by promoting M2 macrophage activity and inhibiting myofibroblast differentiation. This research demonstrates three compounds that have potential to reduce fibrosis and extend the lifetime and efficacy of implantable biomedical devices. / Thesis / Master of Applied Science (MASc) / Capsaicin, prostaglandin E2 (PGE2) and polydopamine were used to reduce scar tissue development around implanted polymers. Biomedical devices implanted in the body can undergo severe scar tissue formation, or fibrosis, and fail. Fibrosis is described by the accumulation of collagen and encapsulation of an implanted polymer. Macrophages regulate fibrosis by secreting pro-fibrotic compounds and myofibroblasts produce unregulated amounts of collagen. In this thesis, capsaicin, PGE2 and polydopamine were incorporated into implants to target macrophage and myofibroblast activity and reduce fibrosis in mice. Capsaicin and PGE2, released from a degradable polymer, altered macrophages to secrete anti-fibrotic compounds and decreased collagen by 40% and 55%, respectively. Polydopamine surface modified implants gave an unexpected result and suppressed overall cell activity to reduce fibrosis by 30%. The research conducted shows the potential of these compounds to reduce fibrosis and extend the lifetime of implantable devices.

A Organização Mundial da Saúde (OMS) relata o câncer como uma das principais causas de morte no mundo. O câncer de próstata é o segundo tipo de câncer mais prevalente em homens. Uma modalidade de tratamento que vem sendo bastante utilizada é a braquiterapia, que consiste na introdução de sementes com material radioativo no interior do orgão. Sementes de Iodo-125 podem ser inseridas soltas ou em cordas poliméricas bioabsorvíveis. As sementes em cordas poliméricas apresentam algumas vantagens, pois reduzem a taxa de migração das sementes, evento que poderia afetar a dosimetria da região e causar danos desnecessários a tecidos ou órgãos sadios. Para as sementes de Iodo-125 em cordas poliméricas, utiliza-se a poliglactina 910, (poli(ácido lático-co-ácido glicólico)) (PLGA), com cobertura de poliglactina 370 (Vicryl®). Foi proposto neste trabalho, o estudo e desenvolvimento da metodologia de síntese do biopolímero PLGA, via polimerização por abertura de anéis, assim como sua caracterização, com o propósito de utilizar o material sintetizado para fabricar um material similar ao RAPID-Strand®. Os resultados obtidos demonstram que, através da metodologia utilizada, foi possível determinar os melhores parâmetros de reação (tempo e temperatura) para o PLGA na proporção 80/20 (lactídeo/glicolídeo). Com uma temperatura de 110ºC e tempo de reação de 24h, foi possível obter 86% de rendimento, e com o aumento o tempo de reação para 72h, o rendimento é superior a 90%. Os valores de massas moleculares obtidas entre os testes, ainda são muito baixos quando comparados com os valores obtidos por outros autores na literatura (cerca de 20%). Falhas na selagem das ampolas, deixando-os vulneráveis à umidade e oxigênio, ou a falta de uma sistema eficiente de agitação podem ser possíveis explicações para estes resultados. Um reator químico adequado poderia solucionar o problema. Em relação à caracterização, as técnicas utilizadas confirmaram a estrutura esperada do polímero, e a maior proporção das unidades provenientes do dímero lactídeo, em relação ao glicolídeo. / According to World Health Organization (WHO), cancer is a leading cause of death worldwide. Prostate cancer is the second most common cancer in men. A method of radiotherapy which has been extensively used is brachytherapy, where radioactive seeds are placed inside the area requiring treatment. Iodine-125 seeds can be placed loose or stranded in bioabsorbable polymers. Stranded seeds show some advantages, since they reduce the rate of seed migration, an event that could affect the dosimetry of the prostate and cause unnecessary damage to healthy tissues or organs. For Iodine-125 stranded seeds, polyglactin 910 (poly(lactic-co-glycolic acid)) (PLGA), with a coverage of polyglactin 370 (Vicryl ®) is used. It was purposed in this dissertation, the study and development of the synthesis methodology for PLGA via ring-opening polymerization, as well as its characterization, with the objective of using the synthesized material to manufacture a material similar to RAPID Strand®. The results obtained show that it was possible to determine the optimal reaction parameters (time and temperature) for PLGA in 80/20 (lactide/glycolide) ratio. Using a temperature of 110 ° C and reaction time of 24h, a yield of 86% was obtained, and increasing the reaction time to 72 hours, the yield was higher than 90%. The molecular mass values obtained from the samples are still very low compared to those obtained by other authors in the literature (about 20%). Failures in the sealing of vials, leaving them vulnerable to moisture and oxygen, or lack of an efficient stirring system might be possible explanations for these results. A suitable chemical reactor could solve the problem. Regarding polymer characterization, all techniques used not only confirmed the expected structure of the polymer, but also showed the highest proportion of lactide units compared to to glycolide units.

A Organização Mundial da Saúde (OMS) relata o câncer como uma das principais causas de morte no mundo. O câncer de próstata é o segundo tipo de câncer mais prevalente em homens. Uma modalidade de tratamento que vem sendo bastante utilizada é a braquiterapia, que consiste na introdução de sementes com material radioativo no interior do orgão. Sementes de Iodo-125 podem ser inseridas soltas ou em cordas poliméricas bioabsorvíveis. As sementes em cordas poliméricas apresentam algumas vantagens, pois reduzem a taxa de migração das sementes, evento que poderia afetar a dosimetria da região e causar danos desnecessários a tecidos ou órgãos sadios. Para as sementes de Iodo-125 em cordas poliméricas, utiliza-se a poliglactina 910, (poli(ácido lático-co-ácido glicólico)) (PLGA), com cobertura de poliglactina 370 (Vicryl®). Foi proposto neste trabalho, o estudo e desenvolvimento da metodologia de síntese do biopolímero PLGA, via polimerização por abertura de anéis, assim como sua caracterização, com o propósito de utilizar o material sintetizado para fabricar um material similar ao RAPID-Strand®. Os resultados obtidos demonstram que, através da metodologia utilizada, foi possível determinar os melhores parâmetros de reação (tempo e temperatura) para o PLGA na proporção 80/20 (lactídeo/glicolídeo). Com uma temperatura de 110ºC e tempo de reação de 24h, foi possível obter 86% de rendimento, e com o aumento o tempo de reação para 72h, o rendimento é superior a 90%. Os valores de massas moleculares obtidas entre os testes, ainda são muito baixos quando comparados com os valores obtidos por outros autores na literatura (cerca de 20%). Falhas na selagem das ampolas, deixando-os vulneráveis à umidade e oxigênio, ou a falta de uma sistema eficiente de agitação podem ser possíveis explicações para estes resultados. Um reator químico adequado poderia solucionar o problema. Em relação à caracterização, as técnicas utilizadas confirmaram a estrutura esperada do polímero, e a maior proporção das unidades provenientes do dímero lactídeo, em relação ao glicolídeo. / According to World Health Organization (WHO), cancer is a leading cause of death worldwide. Prostate cancer is the second most common cancer in men. A method of radiotherapy which has been extensively used is brachytherapy, where radioactive seeds are placed inside the area requiring treatment. Iodine-125 seeds can be placed loose or stranded in bioabsorbable polymers. Stranded seeds show some advantages, since they reduce the rate of seed migration, an event that could affect the dosimetry of the prostate and cause unnecessary damage to healthy tissues or organs. For Iodine-125 stranded seeds, polyglactin 910 (poly(lactic-co-glycolic acid)) (PLGA), with a coverage of polyglactin 370 (Vicryl ®) is used. It was purposed in this dissertation, the study and development of the synthesis methodology for PLGA via ring-opening polymerization, as well as its characterization, with the objective of using the synthesized material to manufacture a material similar to RAPID Strand®. The results obtained show that it was possible to determine the optimal reaction parameters (time and temperature) for PLGA in 80/20 (lactide/glycolide) ratio. Using a temperature of 110 ° C and reaction time of 24h, a yield of 86% was obtained, and increasing the reaction time to 72 hours, the yield was higher than 90%. The molecular mass values obtained from the samples are still very low compared to those obtained by other authors in the literature (about 20%). Failures in the sealing of vials, leaving them vulnerable to moisture and oxygen, or lack of an efficient stirring system might be possible explanations for these results. A suitable chemical reactor could solve the problem. Regarding polymer characterization, all techniques used not only confirmed the expected structure of the polymer, but also showed the highest proportion of lactide units compared to to glycolide units.