Loading...
22 results
Search Results
Now showing 1 - 10 of 22
- 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.
- Structural optimisation for medical implants through additive manufacturingPublication . Al-Tamimi, Abdulsalam Abdulaziz; Almeida, Henrique; Bártolo, PauloAdvanced manufacturing techniques are being explored to fabricate degradable and non-degradable, porous or non-porous implants for medical applications. These implants have been designed using standard computer-aided design (CAD) and computer-aided engineering (CAE) tools and produced in a multitude of materials. The recent use of optimisation tech niques, mainly topology optimisation, allows the development of additive manufactured medical devices with improved performance. This review discusses the combined use of optimisation techniques and additive manufacturing to produce biocompatible and biodegradable scafolds for tissue engineering with improved mechanical and permeability properties; metallic lattice structures with reduced weight and minimal stress shielding efect; and lightweight personalised orthopae dic implants. Three optimisation routes are considered: topology optimisation; triply periodic minimal surfaces that can be manipulated by means of the equations parameters to optimise the overall performance; and the use of repetitive structures that are optimised as unit cells under certain conditions to compose a bulk object. Major limitations and research challenges are highlighted and discussed.
- 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.
- Virtual and Physical Prototyping: EditorialPublication . Bártolo, Paulo; Chua, C.K.; Bartolo, PauloThe second half of 2009 is rich in international events in virtual and physical prototyping, a quite active and relevant research field. The Virtual and Physical Prototyping journal is associated with two of these events. The first one is the ECCOMAS Thematic Conference on Tissue Engineering designed to be a major international forum for the discussion of the current state-of-the-art in the fields of Tissue Engineering Modelling and Simulation. This Conference will focus on: . understanding the fundamentals of tissue engineering; . modelling and characterisation of scaffolds for tissue engineering; . modelling the relationship between scaffold, cell attachment, proliferation and differentiation; . design and development of scaffolds for tissue engineering; . fabrication and testing of scaffolds for tissue engineering; . cell signalling; . computational bone mechanics.
- EditorialPublication . Bartolo, Paulo; Chua, C.K.In this issue of Virtual and Physical Prototyping, there are three Virtual Prototyping papers and two Physical Prototyping papers. Interestingly, three of the five papers relate to the area of bone tissue engineering, an area which is of great and current research interest to readers.
- Study on the fatigue strength of AA 6082-T6 adhesive lap jointsPublication . Pereira, António; Ferreira, J.M.; Antunes, F.V.; Bartolo, PauloA research study on the fatigue behaviour of aluminium alloy adhesive lap joints was carried out to understand the effect of surface pre-treatment and adherends thickness on the fatigue strength of adhesive joints. The adherend material used for the experimental tests was an aluminium alloy 6082-T6 in the form of thin sheets, and the adhesive used was a high strength epoxy (Araldite 420 A/B). The surface preparation included an abrasive preparation (AP joints) and sodium dichromate-sulphuric acid etch (CSA joints). A maximum fatigue strength was obtained for the CSA surface treatment with a 1.0 mm adherends' thickness. The fastest fatigue damage was related with a high surface roughness and a high stress perpendicular to adhesive surface, which helps to promote the adhesive failure. A numerical analysis was also performed to understand the effect of the adherends thickness on the stress level. Results showed an increase of the out-of-plane peak stresses with the increase of adherends thickness.
- 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.
- 3D bioprinting of photocrosslinkable hydrogel constructsPublication . Brás Pereira, Rúben Filipe; Bartolo, PauloThree‐dimensional (3D) bioprinting comprises a group of biofabrication technologies for the additive manufacturing of 3D constructs by precisely printing biocompatible materials, cells and biochemicals in predesigned spatial positions. These technologies have been successfully applied to fabricate biodegradable 3D constructs with intricate architectures and heterogeneous composition, assuming a pivotal role in the field of tissue engineering. However, the full implementation of bioprinting strongly depends on the development of novel biomaterials exhibiting fast crosslinking schemes and appropriate printability, cell‐compatibility and biomechanical properties. Photocrosslinkable hydrogels are attractive materials for bioprinting as they provide fast polymerization under cell‐compatible conditions and exceptional spatiotemporal control over the gelation process. Photopolymerization can also be performed during the bioprinting to promote the instantaneous formation of hydrogel with high well‐defined architecture and structural stability. In this review paper, we summarize the most recent developments on bioprinting of photocrosslinkable biodegradable hydrogels for tissue engineering, focusing on the chemical modification strategies and the combination of photocrosslinking reactions with other gelation modalities.
- 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.
- «
- 1 (current)
- 2
- 3
- »