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Desenvolvimento de novos polímeros biocompatíveis para utilização em ambiente aquático
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Os plásticos, hoje em dia são um tópico com bastante interesse científico e social. Se por um lado é necessário encontrar alternativas de matérias primas para a sua produção, por outro lado são necessários investimentos para a investigação e enquadramento legal para o fabrico de polímeros compatíveis com o ambiente aquático. O ideal seria que estes novos polímeros servissem de alimento às espécies marinhas. Deste modo, sintetizou-se um polímero, o Poli(D,L – Lactídeo co – Glicolídeo) (PLGA) cujos monómeros são biodegradáveis, e que se degradam em compostos que estão presentes nos organismos vivos. A caracterização química e morfológica de uma espécie de medusa foi realizada, com o intuito de verificar se esta espécie apresentaria PLGA na sua constituição e se poderia ser utilizada como uma fonte natural de polímero biodegradável. No estuário de Tejo está presente uma das mais importantes e grandes populações de Cnidários, Catostylus tagi. O corpo desta espécie de medusas possui cerca de 97% de água, são bastante frágeis e possuem menos de 5% de matéria orgânica sólida. As medusas não possuem cérebro, olhos, guelras ou coração. O seu corpo apresenta uma forma do tipo “sino” com simetria radial, constituído por duas camadas de células, e por uma coroa de tentáculos. As medusas foram recolhidas em Maio e Junho de 2018, na região de São João da Talha. Depois de recolhidas, foram lavadas e liofilizadas, para a sua posterior caracterização, por FTIR-ATR, DSC, TGA e SEM. Nas C.tagi liofilizadas, o FTIR-ATR revelou os picos relevantes do colagénio, o maior componente da matriz química da qual estes animais são constituídos. As imagens de SEM revelaram na zona da mesogleia uma rede porosa composta por fibras de colagénio, permitindo que a maioria da água presente nestes animais seja considerada água livre. O Poli(D,L- Lactídeo co-glicolídeo) (PLGA) é considerado um copolímero sintético biodegradável, usado em suturas cirúrgicas, descoberto nos anos 60. Este copolímero contém unidades alternadas de monómeros de glicolídeo e lactídeo. O PLGA é um poliéster hidrofóbico e instável em meios húmidos. Como é aprovado pela Food and Drug Administration (FDA), o interesse por este material tem vindo a crescer o longo dos últimos anos. Este polímero é considerado biodegradável, devido à sua baixa toxicidade e ao facto de ser facilmente degradado no ambiente. O PLGA foi sintetizado por um processo conhecido e sempre na proporção 50:50 de glicolídeo e lactídeo, uma vez que segundo outros estudos foi considerada a proporção com menor tempo de degradação. De seguida procedeu-se à sua caracterização por FTIR-ATR, DSC, TGA e NMR. Em relação à síntese de PLGA, tanto a análise de FTIR-ATR, como a análise termogravimetrica (DSC e TGA), encontram-se de acordo com a literatura revelando que a síntese do polímero foi bem-sucedida, contudo a análise de NMR revelou a existência de dímero de lactídeo por reagir.
The production a novel plastics formulations, nowadays, are a topic with a lot of scientific and social interest. If on the one hand it is necessary to find alternatives of raw materials for their production, on the other hand investments are necessary for research and legal framework for the manufacture of polymers compatible with the aquatic environment. Ideally, these new polymers should serve as food for marine species. A polymer, Poly (D, L-Lactoid co-glycolide) (PLGA) whose monomers are biodegradable, and which degrade in compounds that are present in living organisms, has been synthesized. The chemical and morphological characterization of a jellyfish species was carried out to verify if this species would have PLGA in its constitution and if it could be used as a natural source of biodegradable polymer. In the Tagus estuary one of the most important and large populations of Cnidarians, Catostylus tagi can be found. The body of this species of jellyfish has about 97% water. This animals are quite fragile because they have less than 5% of solid organic matter. Jellyfish have no brain, eyes, gills or heart. Presenting basically a bell-shaped body with radial symmetry, they are composed by two layers of cells, and a crown of tentacles. Jellyfish were collected in May and June 2018, in the region of São João da Talha. After being collected, they were washed and lyophilized, for their later characterization. In the lyophilized C.tagi, its FTIR-ATR revealed the relevant peaks of collagen, the largest component of these animals. SEM images revealed in the mesoglea zone a porous network composed of collagen fibers, allowing most of the water present in these animals to be considered free water. Poly(D,L-Lactide co-glycolide) (PLGA) is considered a synthetic biodegradable copolymer, used in surgical sutures, discovered in the 1960s. This copolymer contains alternating units of glycolide and lactide monomers. The PLGA is a hydrophobic polyester and unstable in wet media, but is also approved by the Food and Drug Administration (FDA), hence its growing interest. This type of polymer is considered biodegradable because of its low toxicity and the fact that it is easily degraded in the environment. PLGA was synthesized by a process described in the literature and always in the 50:50 ratio of glicolide and lactide, since this proportion was the one that presents the longest degradation. Afterwards, it was characterized by DSC, FTIR-ATR, TGA and NMR. Regarding PLGA synthesis, both FTIR-ATR and thermogravimetric analysis (DSC and TGA), agreed with the literature revealing that the polymer synthesis was successful, however the NMR analysis revealed the existence of unreacted lactide dimer.
The production a novel plastics formulations, nowadays, are a topic with a lot of scientific and social interest. If on the one hand it is necessary to find alternatives of raw materials for their production, on the other hand investments are necessary for research and legal framework for the manufacture of polymers compatible with the aquatic environment. Ideally, these new polymers should serve as food for marine species. A polymer, Poly (D, L-Lactoid co-glycolide) (PLGA) whose monomers are biodegradable, and which degrade in compounds that are present in living organisms, has been synthesized. The chemical and morphological characterization of a jellyfish species was carried out to verify if this species would have PLGA in its constitution and if it could be used as a natural source of biodegradable polymer. In the Tagus estuary one of the most important and large populations of Cnidarians, Catostylus tagi can be found. The body of this species of jellyfish has about 97% water. This animals are quite fragile because they have less than 5% of solid organic matter. Jellyfish have no brain, eyes, gills or heart. Presenting basically a bell-shaped body with radial symmetry, they are composed by two layers of cells, and a crown of tentacles. Jellyfish were collected in May and June 2018, in the region of São João da Talha. After being collected, they were washed and lyophilized, for their later characterization. In the lyophilized C.tagi, its FTIR-ATR revealed the relevant peaks of collagen, the largest component of these animals. SEM images revealed in the mesoglea zone a porous network composed of collagen fibers, allowing most of the water present in these animals to be considered free water. Poly(D,L-Lactide co-glycolide) (PLGA) is considered a synthetic biodegradable copolymer, used in surgical sutures, discovered in the 1960s. This copolymer contains alternating units of glycolide and lactide monomers. The PLGA is a hydrophobic polyester and unstable in wet media, but is also approved by the Food and Drug Administration (FDA), hence its growing interest. This type of polymer is considered biodegradable because of its low toxicity and the fact that it is easily degraded in the environment. PLGA was synthesized by a process described in the literature and always in the 50:50 ratio of glicolide and lactide, since this proportion was the one that presents the longest degradation. Afterwards, it was characterized by DSC, FTIR-ATR, TGA and NMR. Regarding PLGA synthesis, both FTIR-ATR and thermogravimetric analysis (DSC and TGA), agreed with the literature revealing that the polymer synthesis was successful, however the NMR analysis revealed the existence of unreacted lactide dimer.
Descrição
Tese de mestrado em Química Tecnológica, Universidade de Lisboa, Faculdade de Ciências, 2019
Palavras-chave
Biopolímero PLGA Catostylus tagi Teses de mestrado - 2019