Estruturas tridimensionais (3D) porosas de derivados tiolados de quitosana produzidas por rota sustentável para potenciais aplicações ambientais e biológicas
| Ano de defesa: | 2018 |
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| Autor(a) principal: | |
| Orientador(a): | |
| Banca de defesa: | |
| Tipo de documento: | Tese |
| Tipo de acesso: | Acesso aberto |
| Idioma: | por |
| Instituição de defesa: |
Universidade Federal de Minas Gerais
UFMG |
| Programa de Pós-Graduação: |
Não Informado pela instituição
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| Departamento: |
Não Informado pela instituição
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| País: |
Não Informado pela instituição
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| Palavras-chave em Português: | |
| Link de acesso: | http://hdl.handle.net/1843/BUOS-B33FMD |
Resumo: | One of the major challenges today in materials science and engineering is the development of sustainable materials produced by chemically friendly routes that do not impact the environment by providing multifunctional materials. In this sense, the modification of the chitosan incorporating the thiol group is very promising, since this modification opens a range of applications ranging from tissue engineering to water treatment, since this grouping allows a better cellular adhesion, as well as a selectivity and chemical interaction enlarged with several materials. In this approach, the present work sought the production of threedimensional materials from a sustainable source through the freeze-drying process, using chitosan modified with different precursors containing the thiol group (SH) (cysteine (CHICys) and mercaptoundodecanoic acid (CHIMerc)) by a friendly chemical route for applications in tissue regeneration and water treatment. In order to understand the mechanisms involved in the functionalization, characterization techniques were used as infrared spectroscopy, Raman spectroscopy, visible ultraviolet spectroscopy, nuclear magnetic resonance, swelling degree, gel-fraction, surface contact, scanning electron microscopy, microtomography, Archimedes, biological cytotoxicity assays such as MTT and LIVE/DEAD with SAOS and HEK cells, and antibacterial activity against Pseudomona aeroginosa. In addition, the scaffolds were applied in the adsorption of the methyl orange, evaluating the kinetics of adsorption, isotherms and the influence of the pH in this adsorption. As the desorption of the pigment was carried out to evaluate the feasibility of reuse. The results showed that the different precursors led to different degrees of functionalization due to the differences in the chains and the method used (CHICys = 5 % and CHIMerc = 26 %). In addition, the three-dimensional structure of thiolated chitosans presented different morphology compared with chitosan, as the porous size ((223±72 µm), (225±95 µm) para a CHICys e CHIMerc, respectively), porosity (> 80 %) and interconnectivity (> 90 %) were suitable to cell growth. The chemical stability and lipophilicity of the material was also different (CHIMerc, GF = 96±3%) or lower (CHICys, GF = 36±4%) depending on the precursor. The results further indicated that the higher chemical stability was provided by the presence of the higher amount of thiol group (CHICys = 409±27 m.g-1 and CHIMerc = 2218±100 m.g-1, obtained with the Ellmans reagent), which provides crosslinks formed by the disulfide bonds, most evident in the CHIMerc sample. This difference in the functionalization and the presence of the thiol group allowed the CHIMerc sample to be applied as an adsorbent to the methyl orange, which presented a high adsorption (400 - 450 mg.g-1 at pH = 7.0±0.2), and the Freundlich model was more suitable to explain the adsorption, which indicates a chemical affinity of the scaffold for the pigment. In addition, the adsorption of the pigment and water at different pH showed that the thiol group is influenced by pH (under basic conditions undergoing oxidation and the adsorption process suffer a decrease (18±1 %), compare with acid (42±3 %) and neutral (91±2 %) conditions). Moreover, the recovery of methyl orange after 2 h of ultrasonication was (82±1) %, (76±2) % and (37±2) % for the EDTA, KCl, and HNO3, respectively indicated the feasibility of its reuse. In addition, this sample presented antibacterial activity against Pseudomona aeroginosa, a very resistant bacterium present in effluents and residual water, which allowed the use of this scaffold as an adsorbent wastewater with this patogen. As well as both scaffolds did not present in vitro cytotoxicity evaluated by the MTT and LIVE/DEAD assays with HEK and SAOS cells favoring its application in tissue regeneration due to the morphology, physicochemical properties and non-toxicity to the biological environment |