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- Development of HA-based hydrogels for biomedical applications using different crosslinkersPublication . Carreira, Joãp Pedro Serradas; Castro, Rita Maria de; Tomás, Helena Maria Pires GasparHyaluronic acid (HA) is a biomolecule that has been widely used in the synthesis of hydrogels, receiving considerable attention due to its unique physiological properties and functions. HA-based hydrogels have been applied in the biomedical field, especially in drug delivery, wound healing, cosmetics, and tissue engineering. However, these hydrogels often face some challenges like their susceptibility to degradation by hyaluronidase, which limits their application to a certain extent. The objective of this thesis was to develop HA-based hydrogels using various crosslinkers, with the goal of creating materials that exhibit enhanced stability and cytocompatibility for potential biomedical applications. Studies were conducted using polyethylene glycol diglycidyl ether (PEGDE), ethylene glycol diglycidyl ether (EGDE), and genipin as crosslinkers, with glutaraldehyde included for comparison as a classical crosslinker. These hydrogels were not only successfully prepared and characterized (e.g., FTIR, SEM), but this thesis also represents the first study to explore hydrogels crosslinked simultaneously by PEGDE and genipin. The prepared hydrogels displayed high swelling capacity and stability in both water and PBS over time. The swelling behavior of the hydrogels was influenced by factors such as the formulation composition, degree of crosslinking, crosslinker length and swelling media. In this regard, greater swelling was observed in water compared to PBS. The in vitro stability and resistance of HA-based hydrogels to enzymatic degradation were influenced by the crosslinking density, with the highest degree of crosslinking producing the most stable and resilient hydrogels. Importantly, the hydrogel crosslinked by both PEGDE and genipin demonstrated particular high swellability and stability. Despite their high stability, the developed hydrogels exhibited significant cytotoxicity, particularly when cells were cultured in direct contact with them. In this context, further studies are needed to draw more definitive conclusions about the biocompatibility of these hydrogels and their potential applications in the biomedical domain.
- Organic farming enhances diversity and recruits beneficial soil fungal groups in traditional banana plantationsPublication . Oliveira, Maria Cristina O.; Alves, Artur; Ragonezi, Carla; Freitas, José G. R. de; Carvalho, Miguel A. A. Pinheiro de; Oliveira, Cristina; Ragonezi, Carla; Almeida Pinheiro de Carvalho, Miguel AngeloThis study investigates the impact of organic (OF) and conventional farming (CF) on soil fungal communities in banana monoculture plantations on Madeira Island. We hypothesized that OF promotes beneficial fungal groups over harmful ones, sustaining soil health. Soil samples were collected from six plantations (three OF and three CF) for ITS amplicon sequencing to assess fungal diversity. Results showed that OF significantly enhanced fungal alpha-diversity (Shannon–Wiener index) and Evenness. The phylum Ascomycota dominated OF systems, while Basidiomycota prevailed in CF. Mortierella, a beneficial genus, was abundant in OF and is observed in CF but was less evident, being the genus Trechispora the most well represented in CF agrosystems. Additionally, OF was associated with higher soil pH and Mg levels, which correlated positively with beneficial fungal groups. Functional analysis revealed that OF promoted saprotrophic fungi, crucial for the decomposition of organic matter and nutrient cycling. However, both systems exhibited low levels of arbuscular mycorrhizal fungi, likely due to high phosphorus levels. These findings suggest that organic practices can enhance soil fungal diversity and health, although attention to nutrient management is critical to further improving soil–plant–fungi interactions.