Percorrer por autor "Mendes, Ausenda"
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- Alginate/Aloe Vera Hydrogel Films for Biomedical ApplicationsPublication . Pereira, Rúben F.; Mendes, Ausenda; Bártolo, PauloThis paper describes a methodology to produce hydrogel films, composed of alginate and Aloe vera, for wound healing and drug delivery applications. The films were prepared through the solvent-casting method and subsequently submitted to an additional cross-linking step to improve their properties. Alginate films with different Aloe vera contents (5, 15 and 25%) were prepared and its properties evaluated in terms of thickness, transparency, swelling behavior and in vitro degradation. Results show a positive influence of Aloe vera on the transparency of the films, in both dry and wet state. Films were immersed in acetate buffer at pH 5.5 simulating the value of the skin, to evaluate its water absorption capacity. It was found that water absorption increases as the Aloe vera content increases, suggesting that Aloe vera enhances the hydrophilic properties of the films. The in vitro degradation tests were performed through the incubation of the films, for 10 weeks, in a simulated body fluid at 37°C. After this period, films kept its structure integrity exhibiting a weight loss in the range of 14.1-18.6%.
- Biopolymer-based manufacturing system for medical applicationsPublication . Lagoa, Ricardo; Bártolo, Paulo; Mendes, Ausenda
- Development of novel alginate based hydrogel films for wound healing applicationsPublication . Pereira, Rúben; Carvalho, Anabela; Vaz, Daniela C.; Gil, M. H.; Mendes, Ausenda; Bártolo, PauloAlginate and Aloe vera are natural materials widely investigated and used in the biomedical field. In this research work, thin hydrogel films composed by alginate and Aloe vera gel in different proportions (95:5, 85:15 and 75:25, v/v) were prepared and characterized. The films were evaluated regarding the light transmission behavior, contact angle measurements, and chemical, thermal and mechanical properties. These thin hydrogel films, prepared by crosslinking reaction using 5% calcium chloride solution, were also investigated relatively to their water solubility and swelling behavior. Results showed that Aloe vera improved the transparency of the films, as well their thermal stability. The developed films present adequate mechanical properties for skin applications, while the solubility studies demonstrated the insolubility of the films after 24 h of immersion in distilled water. The water absorption and swelling behavior of these films were greatly improved by the increase in Aloe vera proportion.
- Evaluating the Properties of an Alginate Wound Dressing for Skin RepairPublication . Pereira, Rúben F.; Mendes, Ausenda; Bártolo, Paulo J.The treatment of skin lesions is a costly and complex process, for which different strategies are currently available. In this study, we investigated the properties of novel films composed of alginate and aloe vera gel for application as wound dressing material. The films combine the occlusive and haemostatic properties of calcium alginate gels with the therapeutic properties of aloe vera. We expect that these films may improve the healing process through the release of aloe vera compounds directly into the wound bed and could be an alternative to the administration of synthetic drugs to infected wounds. The films exhibited high transparency in both dry and wet state, as well as adequate mechanical properties for skin use. The results indicated that the films present great potential to be explored as wound dressing material.
- Influence of Aloe vera on water absorption and enzymatic in vitro degradation of alginate hydrogel filmsPublication . Pereira, Rúben F.; Carvalho, Anabela; Gil, M.H.; Mendes, Ausenda; Bártolo, Paulo J.This study investigates the influence of Aloe vera on water absorption and the in vitro degradation rate of Aloe vera-Ca-alginate hydrogel films, for wound healing and drug delivery applications. The influence of A. vera content (5%, 15% and 25%, v/v) on water absorption was evaluated by the incubation of the films into a 0.1 M HCl solution (pH 1.0), acetate buffer (pH 5.5) and simulated body fluid solution (pH 7.4) during 24 h. Results show that the water absorption is significantly higher for films containing high A. vera contents (15% and 25%), while no significant differences are observed between the alginate neat film and the film with 5% of A. vera. The in vitro enzymatic degradation tests indicate that an increase in the A. vera content significantly enhances the degradation rate of the films. Control films, incubated in a simulated body fluid solution without enzymes, are resistant to the hydrolytic degradation, exhibiting reduced weight loss and maintaining its structural integrity. Results also show that the water absorption and the in vitro degradation rate of the films can be tailored by changing the A. vera content.
- Monitoring the modifications of Aloe vera by high performance liquid chromatographyPublication . Tojeira, Ana; Pereira, Rúben; Bártolo, Paulo; Mendes, Ausenda; Vaz, Daniela; Oliveira, Nelson SimõesAloe vera is a widely known and studied plant due to its therapeutic properties. The therapeutic properties exhibited by the Aloe vera exudates have been associated to the presence of certain compounds, such as, chromones, anthrones and anthraquinones. In this study, we have identified, and monitored by reversed phase high performance liquid chromatography (HPLC), six major compounds present in the Aloe vera exudates. The chromatographic profiles were followed in the course of time and at different wavelengths. This monitoring allowed us to verify the constitution and modifications of the samples, in order to identify the main changes responsible for the chemical degradation and loss of proprieties exhibited by the exudates over time.
- Novel Alginate/Aloe Vera Hydrogel Blends as Wound Dressings for the Treatment of Several Types of WoundsPublication . Pereira, Rúben F.; Mendes, Ausenda; Bártolo, Paulo J.Currently, there is a significant increase in the use of natural materials for biomedical applications, mainly due to their biocompatibility, biodegradability and similar properties to the constituents of natural tissues. In this work, hydrogel films composed of alginate and Aloe vera gel were prepared and characterized for application in the treatment of several types of wounds (e.g. exuding, painful and dry). The films were prepared through a two-step procedure encompassing the film formation by a solvent-casting method and an additional crosslinking step to improve their properties. The physical, morphological and water absorption properties were characterized by introducing several variations in the Aloe vera content. The in vitro degradation behaviour of the films was investigated in the presence of the enzyme alginate lyase for 2 weeks. Results showed that Aloe vera improves the water absorption and the in vitro degradation rate of the films. In conclusion, this study indicates that the alginate/Aloe vera hydrogel films can be potentially explored as wound dressing for the treatment of different wound types.
- Optimization of Scaffolds in Alginate for Biofabrication by Genetic AlgorithmsPublication . Rezende, Rodrigo; Rezende, Mylene; Bártolo, Paulo; Mendes, Ausenda; Filho, Rubens Maciel; Bartolo, Paulo; Mendes, AusendaWith an increasing in the rate of transplants due to damaged or affected tissues or organs by accidents or diseases and also by the aging of the population in many countries as Brazil, have motivated the research of some novel and alternative ways focused on restoring and replacing tissues. Biofabrication by means of Rapid Prototyping techniques can help in the fashioning and final production of scaffolds devoted to support and stimulate the growth of new tissues. For soft tissues, a biomaterial known as Alginate has been studied and used as raw-material for scaffolds fabrication. A scaffold must guarantee good strength and stiffness at the same time the material degrades gradually. In this work, a single mathematical model experimentally obtained that describes an interesting mechanical behavior of the degradation of alginated-scaffolds is developed. The optimization process scheme using Genetic Algorithms to maximize the elastic modulus and therefore to aid the design of scaffolds in alginate is proposed. The optimization is very welcome to tissue engineering and Biofabrication.
- PCL Scaffolds with Collagen Bioactivator for Applications in Tissue EngineeringPublication . Sousa, Inês; Mendes, Ausenda; Bártolo, Paulo J.The need for human tissues is fundament in certain genetic diseases or accidents of everyday life, they are a primary source for public health. In recent years, to alleviate these effects there was an improvement in the development of tissue engineering, scaffolds or matrices, to support an adequate mechanical and biological environment necessary for the regeneration of damaged tissues. These scaffolds are structures allowing adhesion, differentiation, cell proliferation and the supply of nutrients for growing cells. This paper aims to obtain PCL scaffolds bioactivators, to use as support matrices for the development of human tissues, as PCL is a biomaterial widely used in the biomedical field, due to its biocompatibility, mechanical strength and biodegradability. However, this biomaterial is hydrophobic, which means that there are difficulties in cell adhesion. To solve this problem, a coating of PCL scaffolds with collagen was used, since collagen is a hydrophilic protein existing in the formation of various tissues, so improves cell adhesion.
- Preparation and Characterization of Films Based on Alginate and Aloe VeraPublication . Brás Pereira, Rúben Filipe; Tojeira, Ana; Barroso de Moura Cipreste Vaz, Daniela; Mendes, Ausenda; Bartolo, Paulo; Mendes, AusendaSodium alginate films with aloe vera extract were prepared by the casting/solvent evaporation technique. The resulting films were characterized by differential scanning calorimetry, Fourier transform-infrared spectroscopy, scanning electron microscopy, and mechanical and water absorption tests. The in vitro degradation of the films was also investigated over 14 days. Results show that aloe vera contributes to both enhancing the thermal and mechanical properties of the films and decreasing the weight loss during in vitro degradation.