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- Poly(vinyl alcohol)/chitosan asymmetrical membranes: Highly controlled morphology toward the ideal wound dressingPublication . Morgado, Patrícia I.; Lisboa, Pedro; Ribeiro, MP.; Miguel, Sónia P.; Simões, Pedro; Correia, Ilídio Joaquim Sobreira; Ricardo, Ana AguiarAsymmetrical membranes have been reported as ideal wound dressings for skin regeneration. The usual methods (dry/wet-phase inversion) to produce those specific membranes are time consuming, and in majority of the cases demand the use of harmful organic solvents. In this study, supercritical carbon dioxide (scCO2)-assisted phase inversion method was applied to prepare poly(vinyl alcohol)/chitosan (PVA/CS) asymmetrical membranes. This technique can tailor the final structure of the dressing by tuning the processing conditions allowing the development of high porous materials with optimized morphology, mechanical properties and hydrophilicity. The PVA/CS dressings produced are recovered in a dry state but can form a hydrogel due to their high water uptake ability maintaining the moisturized environment needed for wound healing. The dressing presents a top thin layer of about 15 µm that allows gaseous exchange while barricading the penetration of microorganisms, and a sponge bottom layer that is able to remove excess exudates. A mathematical model based on Fick׳s second law of diffusion was developed to describe the pharmacokinetic release profile of a small drug (ibuprofen) from the swollen membrane in physiological conditions that mimic the wound. In vitro studies revealed that the dressings had excellent biocompatibility and biodegradation properties adequate for skin wound healing.
- Dextran-based hydrogel containing chitosan microparticles loaded with growth factors to be used in wound healingPublication . Ribeiro, MP.; Morgado, Patrícia I.; Miguel, Sónia P.; Coutinho, Paula Isabel Teixeira Gonçalves; Correia, Ilídio Joaquim SobreiraSkin injuries are traumatic events, which are seldom accompanied by complete structural and functional restoration of the original tissue. Different strategies have been developed in order to make the wound healing process faster and less painful. In the present study in vitro and in vivo assays were carried out to evaluate the applicability of a dextran hydrogel loaded with chitosan microparticles containing epidermal and vascular endothelial growth factors, for the improvement of the wound healing process. The carriers' morphology was characterized by scanning electron microscopy. Their cytotoxicity profile and degradation by-products were evaluated through in vitro assays. In vivo experiments were also performed to evaluate their applicability for the treatment of skin burns. The wound healing process was monitored through macroscopic and histological analysis. The macroscopic analysis showed that the period for wound healing occurs in animals treated with microparticle loaded hydrogels containing growth factors that were considerably smaller than that of control groups. Moreover, the histological analysis revealed the absence of reactive or granulomatous inflammatory reaction in skin lesions. The results obtained both in vitro and in vivo disclosed that these systems and its degradation by-products are biocompatible, contributed to the re-establishment of skin architecture and can be used in a near future for the controlled delivery of other bioactive agents used in regenerative medicine.
- Ibuprofen loaded PVA/chitosan membranes: A highly efficient strategy towards an improved skin wound healingPublication . Morgado, Patrícia I.; Miguel, Sónia P.; Correia, Ilídio Joaquim Sobreira; Ricardo, Ana AguiarDuring wound healing, an early inflammation can cause an increase of the wound size and the healing process can be considerably belated if a disproportionate inflammatory response occurs. (S)-ibuprofen (IBP), a non-steroidal anti-inflammatory agent, has been used for muscle healing and to treat venous leg ulcers, but its effect in skin wound healing has not been thoroughly studied thus far. Herein, IBP-β-cyclodextrins carriers were designed to customise the release profile of IBP from poly(vinyl alcohol)/chitosan (PVA/CS) dressings in order to promote a faster skin regeneration. The dressings were produced using supercritical carbon dioxide (scCO2)-assisted technique. In vitro IBP release studies showed that β-cyclodextrins allowed a controlled drug release from the hydrogels which is crucial for their application in wound management. Moreover, the in vivo assays revealed that the presence of PVA/CS membranes containing IBP-β-cyclodextrins carriers avoided scab formation and an excessive inflammation, enabling an earlier skin healing.