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- 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.
- Biopolymer-based manufacturing system for medical applicationsPublication . Lagoa, Ricardo; Bártolo, Paulo; Mendes, Ausenda
- 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.
- Rheological behavior of alginate solutions for biomanufacturingPublication . Rezende, Rodrigo Alvarenga; Bartolo, Paulo; Mendes, Ausenda; Filho, Rubens MacielThe rheological behavior of alginate solutions were investigated for the optimal design of a biomanufacturing system to produce alginate structures for tissue engineering. Its rheological properties were determined by a rheometer through rotational and oscillatory I tests. Experimental results were used to model the alginate solutions characteristics. The findings suggest that alginate solutions undergo shear-thinning effects with increasing shear rates. It is also possible to observe that its loss modulus is higher than the storage modulus ones being both modulus dependent upon the frequency, which is a typical characteristic of dilute solutions.
- Produção de peças biodegradáveis de parede fina por injeçãoPublication . Santos, C.; Mendes, A.; Carreira, P.; Mateus, A.; Alves, N.Actualmente, a indústria dos moldes para responder às exigências do mercado procura diversificar os seus mercados, apostando em produtos diferenciados e de valor acrescentado. Foi neste sentido que se desenvolveu o projecto de concepção e fabrico de vasos biodegradáveis para germinação de plantas. O objectivo deste artigo de investigação passa pela concepção e desenvolvimento de um vaso para germinação de plantas produzido em material biodegradável. A validação do projecto desenvolvido para uma peça de paredes finas em material biodegradável, foi realizada através da fabricação da ferramenta (molde) e o processamento de peças (vasos biodegradáveis). Este estudo demonstrou-se promissor como pilar de apoio para o desenvolvimento de futuros produtos em materiais biodegradáveis de paredes finas, obtidos pelo processo de injecção de termoplásticos. Os resultados alcançados permitiram validar o processo desenvolvido, bem como o produto obtido de paredes finas em material biodegradável, que neste caso foi um vaso biodegradável para germinação de plantas.
- 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.