A carregar...
3 resultados
Resultados da pesquisa
A mostrar 1 - 3 de 3
- Towards the development of electrospun mats from poly(ε-caprolactone)/poly(ester amide)s miscible blendsPublication . Lamas, Miguel; Lima, Mafalda S.; Pinho, AC; Tugushi, David; Katsarava, Ramaz; Costa, Elisabete C.; Correia, Ilídio Joaquim Sobreira; Serra, Armenio; Coelho, Jorge; Fonseca, Ana C.In this work, electrospun mats made from miscible poly(ε-caprolactone) (PCL)/poly(ester amide) (PEA) blends were prepared, for the first time. The well-known immiscibility issues between these two type of polymers were overcome through the synthesis of a novel tailor-made compatibilizer blocky PEA, comprising well defined PCL and PEA8L6 blocks (PCL-PEA8L6). The PCL-PEA8L6 was synthesized for the first time in this work and was characterized in terms of its chemical structure and thermal properties. Regarding the mats, it was found that their properties (morphology, porosity, wettability, thermomechanical) can be easily adjusted by the ratio of the components of the mixture to be electrospun. Increasing amounts of PEA led to more hydrophilic mats, with enhanced in vitro degradability, both hydrolytic and enzymatic. The in vitro cytotoxicity tests carried out with normal human dermal fibroblasts (NHDF) revealed that the samples do not elicit any acute adverse effect on the cells. Moreover, the NHDF were able to grow and proliferate in the surface of the electrospun mats. The data presented in this contribution is a proof-of-concept that can be used to address immiscibility issues between different types of polymers broadly used in biomedical applications.
- HLA‐A23/HLA‐A24 serotypes and dementia interaction in the elderly: Association with increased soluble HLA class I molecules in plasmaPublication . Cardoso, Elsa M.; Gomes, Vânia Lourenço; Esgalhado, André J.; Ferreira, Débora Reste; Oliveira, Nádia; Amaral, Ana Saraiva; Martinho, António; Gama, Jorge; Verde, Ignacio; Lourenço, Olga; Fonseca, Ana C.; Buchli, Rico; Arosa, Fernando A.MHC class I molecules regulate brain development and plasticity in mice and HLA class I molecules are associated with brain disorders in humans. We investigated the relationship between plasma-derived soluble human HLA class I molecules (sHLA class I), HLA class I serotypes and dementia. A cohort of HLA class I serotyped elderly subjects with no dementia/predementia (NpD, n = 28), or with dementia (D, n = 28) was studied. Multivariate analysis was used to examine the influence of dementia and HLA class I serotype on sHLA class I levels, and to compare sHLA class I within four groups according to the presence or absence of HLA-A23/A24 and dementia. HLA-A23/A24 and dementia, but not age, significantly influenced the level of sHLA class I. Importantly, the concurrent presence of HLA-A23/A24 and dementia was associated with higher levels of sHLA class I (p < 0.001). This study has shown that the simultaneous presence of HLA-A23/HLA-A24 and dementia is associated with high levels of serum sHLA class I molecules. Thus, sHLA class I could be considered a biomarker of neurodegeneration in certain HLA class I carriers.
- Poly(ester amide)s based on (L)-lactic acid oligomers and α-amino acids: influence of the α-amino acid side chain in the poly(ester amide)s propertiesPublication . Fonseca, Ana C.; Coelho, Jorge; Valente, Joana; Correia, Tiago R.; Correia, Ilídio Joaquim Sobreira; Gil, Maria; Simões, PedroNovel biodegradable and low cytotoxic poly(ester amide)s (PEAs) based on α-amino acids and (L)-lactic acid (L-LA) oligomers were successfully synthesized by interfacial polymerization. The chemical structure of the new polymers was confirmed by spectroscopic analyses. Further characterization suggests that the α-amino acid plays a critical role on the final properties of the PEA. L-phenylalanine provides PEAs with higher glass transition temperature, whereas glycine enhances the crystallinity. The hydrolytic degradation in PBS (pH = 7.4) at 37 °C also depends on the α-amino acid, being faster for glycine-based PEAs. The cytotoxic profiles using fibroblast human cells indicate that the PEAs did not elicit an acute cytotoxic effect. The strategy presented in this work opens the possibility of synthesizing biodegradable PEAs with low citotoxicity by an easy and fast method. It is worth to mention also that the properties of these materials can be fine-tuned only by changing the α-amino acid.