Browsing by Author "Dias, J.R."
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- Biomechanical performance of hybrid electrospun structures for skin regenerationPublication . Dias, J.R.; Baptista-Silva, S.; Sousa, A.; Oliveira, A. L.; Bártolo, P. J.; Granja, P. L.Wound dressings made by electrospun nanofibers have been demonstrating great potential to regenerate skin tissue as compared to the conventional membrane products available in the market. Until today most of the developed dressings have only demonstrated the capability to regenerate the dermis or epidermis. In this study we propose new hybrid electrospun meshes combining polycaprolactone and gelatin. Several approaches, multilayer, coating and blend were stablished to investigate the most appropriate hybrid structure with potential to promote skin regeneration in its full thickness. The structures were evaluated in terms of physico-chemical properties (porosity, water vapor permeability, contact angle and swelling degree) and according to its mechanical and biological performance. Multilayer and blend structures demonstrated to fit most of native skin requirements. However, looking to all the performed characterization we considered multilayer as the most promising hybrid structures, due its high porosity which contributed to an ideal water vapor permeability rate and good mechanical and biological properties. Based on this multilayer structure is a promisor wound dressing.
- Box-Behnken Design a Key Tool to Achieve Optimized PCL/Gelatin Electrospun Mesh, Macromolecular Materials and EngineeringPublication . Guerreiro, S.F.C.; Valente, J.F.A.; Dias, J.R.; Alves, N.Hybrid electrospun nanofibers of polycaprolactone (PCL)/gelatin are considered as drug-delivery systems for increasing the treatment efficacy in superficial (skin) wounds. Continuous delivery of therapeutic agents, skin extracellular matrix similarity, management of wound exudate, and antimicrobial barrier effect are the major advantages of electrospun nanofibers in skin applications. Additionally, combining the favorable properties of PCL and gelatin, regarding their biocompatibility, biodegradability and mechanical performance have been revealed promising parameters to be considered for blend in hybrid structures. However, the usual optimization protocol of nanofibers’ production in electrospinning is based on the observation of one-variable-attime being this methodology expensive and time-consuming. Therefore, in this research work, a statistical model based on four input variables namely, the flow rate, the needle-working distance, the applied voltage, and the ratio of PCL in the solution, is developed to predict the behavior of nanofibers. The performance of nanofibers is monitored by measurements of fiber’s diameter, mesh’s thickness, and mesh’s permeability. Overall, the model showed to be statistically significant (p-value < 0.05) and an independent analysis validated the predicted response for optimal condition. Finally, a delivery study is performed to evaluate the electrospun mesh performance as a drug carrier.
- Composite Central Face Design—An Approach to Achieve Efficient Alginate MicrocarriersPublication . Valente, J.F.A.; Dias, J.R.; Sousa, A.; Alves, N.Microparticulated drug delivery systems have been used as promising encapsulation systems for protecting drugs for in vitro and in vivo applications, enhancing its stability, providing an increased surface to volume ratio, reducing adverse effects, and hence an improvement in bioavailability. Among the studied microparticles, there is a rising interest in the research of alginate microparticles for pharmaceutical and biomedical fields confirming its potential to be used as an effective matrix for drug and cell delivery. Moreover, calcium alginate has been one of the most extensively forming microparticles in the presence of divalent cations providing prolonged drug release and suitable mucoadhesive properties. Regarding the above mentioned, in this research work, we intended to produce Ca-alginate micro-vehicles through electrospraying, presenting high encapsulation efficiency (EE%), reduced protein release across the time, reduced swelling effect, and high sphericity coefficient. To quickly achieve these characteristics and to perform an optimal combination among the percentage of alginate and CaCl2, design of Experiments was applied. The obtained model presented to be statistically significant (p-value < 0.05), with a coefficient of determination of 0.9207, 0.9197, 0.9499, and 0.9637 for each output (EE%, release, swelling, and sphericity, respectively). Moreover, the optimal point (4% of alginate and 6.6% of CaCl2) was successfully validated.