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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.
- Asymmetric membranes as ideal wound dressings: An overview on production methods, structure, properties and performance relationshipPublication . Morgado, Patrícia I.; Ricardo, Ana Aguiar; Correia, I.J.Healing a wound is a process that comprises sequential steps aimed to restore the structure and function of damaged cells and tissues. Since the antiquity, to promote an effective wound healing, different materials have been used to cover the wound. Nowadays, dressings that are able to mimic the structure and composition of skin are specifically designed to exhibit several required functions. To cope with this demand, different wound dressings have been produced using conventional techniques, during the last two decades. Among them, asymmetric ones present a dense top layer to protect the wound from physical damage and pathogen penetration and an inner porous layer that allows the exudates absorption, keeping the moisturized environment needed for effective skin regeneration. However, the production methods used so far, wet- and dry/wet-phase inversion techniques, present some limitations such as the use of toxic organic solvents, the lack of polymers variety and are very time-consuming. In addition, taking into account the worldwide economic status, sustainable procedures, like supercritical carbon dioxide (scCO2) – assisted phase inversion and electrospinning techniques can be adopted to produce suitable dressings for wound-management. Herein, a critical review of the methods used to produce asymmetric membranes is presented, highlighting the different properties that can be enhanced for wound healing purposes.
- 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.