Browsing by Author "Sequeira, Rosa Maria Saraiva"
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- Desenvolvimento de uma nova membrana bioativa para o tratamento de lesões da pelePublication . Sequeira, Rosa Maria Saraiva; Correia, Ilídio Joaquim Sobreira; Miguel, Sónia Alexandra PereiraThe skin is the outermost organ of the body and its acts as a protective barrier. Furthermore, skin is also responsible for the regulation of the body temperature and also for the maintenance of homeostasis. However, different types of injuries (burns, surgical interventions and/or chronic wounds), affect skin structure and functions. When a skin injury occurs, it is crucial to cover the wound site as soon as possible to provide protection against external agents. Despite this, there are several therapeutic strategies available for the treatment of skin injuries, none of them is able to restore all morphological and biological properties of the skin. In this context, Tissue Engineering researchers aim to produce polymeric and biocompatible matrices capable of reproducing the native structure of the skin, as well as, promote cell adhesion and proliferation. Among the different types of materials produced so far, the nanofibrous membranes produced by the electrospinning technique have demonstrated promising properties to be used in wound dressing applications. Thus, the work presented in this dissertation intended to produce and characterize a nanofibrous membrane. Poly(vinyl alcohol) (PVA) and lysine (Lys) were selected to produce the membrane, then functionalized with ibuprofen (IBP) (an anti-inflammatory molecule), and lavender oil (LO) (an antibacterial molecule). The IBP was incorporated into the nanofibers through an electrospinning blend technique, in order to be released in controlled and sustained fashion during the inflammatory phase (1-3 days after injury), while the LO was incorporated into the membrane’ surface through physical adsorption technique, to allow an initial burst release which is essential to prevent the occurrence of infections at wound site. In this way, the produced membrane will allow to control the inflammatory process and avoid the occurrence of skin infections. Indeed, the antimicrobial assays demonstrated that LO functionalized membranes exhibited excellent antibacterial activity against S.aureus and P.aeruginosa. All the gathered data revealed that the PVA_Lys membrane incorporated with IBP and LO possess the suitable morphological, mechanical and biological properties to be used as wound dressing.
- Development of a poly(vinyl alcohol)/lysine electrospun membrane-based drug delivery system for improved skin regenerationPublication . Sequeira, Rosa Maria Saraiva; Miguel, Sónia; Cabral, Cátia S. D.; Moreira, André; Ferreira, Paula; Correia, I.J.Nanofiber-based wound dressings are currently being explored as delivery systems of different biomolecules for avoiding skin infections as well as improve/accelerate the healing process. In the present work, a nanofibrous membrane composed of poly(vinyl alcohol) (PVA) and lysine (Lys) was produced by using the electrospinning technique. Further, anti-inflammatory (ibuprofen (IBP)) and antibacterial (lavender oil (LO)) agents were incorporated within the electrospun membrane through blend electrospinning and surface physical adsorption methods, respectively. The obtained results demonstrated that the PVA_Lys electrospun membranes incorporating IBP or LO displayed the suitable morphological, mechanical and biological properties for enhancing the wound healing process. Moreover, the controlled and sustained release profile attained for IBP was appropriate for the duration of the wound healing inflammatory phase, whereas the initial burst release of LO is crucial to prevent wound bacterial contamination. Indeed, the PVA_Lys_LO electrospun membranes were able to mediate a strong antibacterial activity against both S. aureus and P. aeruginosa, without compromising human fibroblasts viability. Overall, the gathered data emphasizes the potential of the PVA_Lys electrospun membranes-based drug delivery systems to be used as wound dressings.
- Production and characterization of electrospun silk fibroin based asymmetric membranes for wound dressing applicationsPublication . Miguel, Sónia P.; Simões, Déborah; Moreira, André; Sequeira, Rosa Maria Saraiva; Correia, Ilídio Joaquim SobreiraNowadays, wound dressings with improved properties are under development and among them, asymmetric membranes have gained an increasing interest due to their two-layered structure that mimic both the epidermis and dermis layers of the skin. Herein, a new asymmetric membrane was produced using the electrospinning technique. The top layer was produced with silk fibroin (SF) and poly(caprolactone) to reproduce the dense nature and waterproof ability of the epidermis. On the other hand, the dermis-like bottom layer was manufactured with SF and hyaluronic acid loaded with an herbal drug (thymol (THY)). All the data gathered showed that the produced electrospun asymmetric membrane exhibited the porosity, wettability, and mechanical properties suitable for the healing process. Further, the in vitro data also demonstrated that the human fibroblast is able to adhere and spread at the membranes' surface, thus confirming their biocompatibility. Moreover, the incorporation of THY into the bottom layer of the membrane, improved its antioxidant and antibacterial properties. Overall, the obtained results demonstrate the appropriateness of the produced membrane for wound healing applications.