A carregar...
Publicação
Biopolymeric substrates for reconstructed dermis development
| Nome: | Descrição: | Tamanho: | Formato: | |
|---|---|---|---|---|
| 5.02 MB | Adobe PDF |
Autores
Orientador(es)
Resumo(s)
The first goal of this thesis was the production of polyhydroxyalkanoates (PHAs) with differing material properties, namely medium-chain-length polyhydroxyalkanoates (mcl-PHAs), elastic and tacky polymers, and short-chain-length polyhydroxyalkanoates (scl-PHAs), specifically P(3HB) and P(HBHV), which are more crystalline and brittle. All three biopolymers were successfully biosynthesised. Glycerol was used for the batch cultivation of Pseudomonas chlororaphis DSM 19603 for mcl-PHA production and used cooking oil was employed for the batch fermentation of Cupriavidus necator DSM 428 for P(3HB) and P(HBHV) production. Concerning P(HBHV), 3HV (25%) was incorporated into the polymer by means of feeding levulinic acid as co-substrate. mcl-PHA was mainly composed of 3-hydroxydecanoate (64%) and 3-hydroxyoctanoate (16%) and had a molecular weight of 0.69×105 Da. It presented a degradation temperature of 292 °C and a crystallinity degree of 3.7%. P(3HB) was obtained with a molecular weight of 5.2×105 Da and a crystallinity degree of 41.3%. Moreover, the polymer had melting and thermal degradation temperatures of 175 and 293 °C, respectively. P(HBHV) presented melting and degradation temperatures of 176 and 292 ˚C, respectively, and a crystallinity fraction of 17.8%.
The aim for the second part of this work was to prepare porous/fibrous PHA-based scaffolds, followed by their physical and chemical characterization. Several techniques were employed, namely, solvent casting with particulate leaching (SCPL), supercritical CO2 (scCO2), emulsion templating and electrospinning. Emulsion templating and electrospinning displayed the most promising results in implementing porosity without compromising the characteristics of the polymer. Electrospinning allowed the fabrication of a P(HBHV)/mcl-PHA blend with enhanced mechanical properties. Furthermore, oxygen plasma and UV/ozone surface modification techniques were tested, and oxygen plasma offered enhanced hydrophilicity while not significantly impacting polymer integrity.
Finally, scaffolds bioactivity was investigated. Human dermal fibroblasts were able to adhere and proliferate in electrospun PHA-based scaffolds, with P(HBHV)/mcl-PHA oxygen plasma-treated showing the most promising results (40% attachment). This work demonstrated the potential of PHAs as materials for the development of new 3D-scaffolds for skin reconstitution.
Descrição
Palavras-chave
short-chain length polyhydroxyalkanoates (scl-PHA) medium-chain length polyhydroxyalkanoates (mcl-PHA) PHA-based scaffolds dermis reconstitution