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- Synthesis and characterization of a photocrosslinkable chitosan–gelatin hydrogel aimed for tissue regenerationPublication . Saraiva, Sofia Mendes; Miguel, Sónia P.; Ribeiro, MP.; Coutinho, Paula Isabel Teixeira Gonçalves; Correia, Ilídio Joaquim SobreiraIn the area of tissue engineering different approaches have been studied, so far, for promoting regeneration or replacement of damaged tissues. Among the different materials developed, hydrogels, due to their biocompatibility and similarities with the native extracellular matrix, have emerged as suitable candidates for being used for different therapeutic purposes. Herein, photocrosslinkable hydrogels, composed by chitosan methacrylamide (ChMA) and gelatin methacrylamide (GelMA) were crosslinked by ultraviolet (UV) light, using Irgacue 2959 as photoinitiator. The morphological, physicochemical and biological properties of the hydrogels were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and nuclear magnetic resonance. The obtained results demonstrated that the developed hydrogels possess suitable properties for being used as 3D constructs on several areas of tissue engineering. Furthermore, these properties may allow their future application as space filling agents or as delivery vehicles of bioactive molecules and cells.
- PVP-coated silver nanoparticles showing antifungal improved activity against dermatophytesPublication . Silva, Stephane Edgar da; Saraiva, Sofia M; Miguel, Sónia P.; Correia, Ilídio Joaquim SobreiraFungal infections affecting human beings have increased during the last years and the currently available treatments, when administered for long periods, trigger microbial resistance. Such demands the development of new viable therapeutic alternatives. Silver is known since the antiquity by its antimicrobial properties and, herein, it was used to produce two types of nanoparticles (NPs), uncoated and coated with polyvinylpyrrolidone (PVP), which were aimed to be used in fungal infection treatment. NPs properties were characterized by Transmission electron microscopy, X-ray diffraction, UV–Vis, Dynamic light scattering, Fourier transform infrared, and Energy-dispersive X-ray spectroscopy. Furthermore, in vitro studies were also performed to evaluate NPs cytotoxic profile and antifungal activity. The results obtained revealed that the produced nanoparticles are biocompatible and have a good potential for being used in the treatment of common skin infections caused by Trichophyton rubrum and Trichophyton mentagrophytes, being PVP-coated silver NPs the most suitable ones.
- Novel therapeutic approaches for skin regenerationPublication . Saraiva, Sofia Mendes; Borges, Paula Isabel Teixeira Gonçalves Coutinho; Correia, Ilídio Joaquim Sobreira; Ribeiro, Maximiano José PrataThe integrity of skin, as the largest organ of the human body, must be preserved in order to play its role as a protective barrier, in the maintenance of fluid homeostasis and temperature regulation. Skin lesions can occur due to different causes, being burns those responsible for extensive skin loss, infection, electrolyte imbalances and respiratory failure. In order to decrease the effects of skin damages, new skin substitutes have been developed to accelerate the healing process and thus restore the native structure of skin. Among the existent materials, hydrogels own the most desirable characteristics of an “ideal dressing”, such as biocompatibility and biodegradability. Currently, new photocrosslinkable hydrogels have been developed for tissue engineering purposes. Taking into account the intrinsic properties of hydrogels, the work plan developed during this master thesis allowed the production of photocrosslinkable hydrogels, composed of chitosan and gelatine that present some of the properties required for wound regeneration. Initially, methacrylate groups were added to the chitosan and gelatine primary amine groups, leading to the synthesis of methacrylamide chitosan (MAC) and methacrylamide gelatine (MAG). The chemical modification of the polymers was confirmed by proton nuclear magnetic resonance (1H NMR). Then, MAC and MAG hydrogels were produced using ultraviolet (UV) light in the presence of a photoinitiator (Irgacue 2959). The hydrogels were subsequently characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. Porosity and swelling properties were also analyzed and revealed that the hydrogels with a higher content of chitosan had higher porosity and swelling capacity. The cytotoxic profile of the hydrogels was evaluated through an MTS assay, using human fibroblast cells. Cell adhesion on the surface of the hydrogels was visualized through scanning electron microscopy. The results obtained demonstrated that the hydrogels developed herein possess suitable properties for being used as wound dressings. Therefore, in the future in vivo studies will be performed to evaluate the histocompatibility of the hydrogels and their capacity to improve the wound healing process. In addition, growth factors and antimicrobial agents can be incorporated in the hydrogels, in order to improve wound repair and prevent bacterial infections, respectively.