Unidade de Investigação - CDRsp – Centro para o Desenvolvimento Rápido e Sustentado de Produto
Permanent URI for this community
Browse
Browsing Unidade de Investigação - CDRsp – Centro para o Desenvolvimento Rápido e Sustentado de Produto by Title
Now showing 1 - 10 of 322
Results Per Page
Sort Options
- 316L stainless steel mechanical and tribological behavior—A comparison between selective laser melting, hot pressing and conventional castingPublication . Bartolomeu, F.; Buciumeanu, M.; Pinto, E.; Alves, Nuno; Carvalho, O.; Silva, F: S.; Miranda, G.This work presents a comprehensive study on the influence of three different processing technologies (Selective Laser Melting, Hot Pressing and conventional casting) on the microstructure, mechanical and wear behavior of an austenitic 316L Stainless Steel.Acorrelation between the processing technologies,the obtained microstructure and the mechanical and wear behavior was achieved. The results showed that the highest mechanical properties and tribological performance were obtained for 316L SS specimens produced by Selective Laser Melting, when compared to Hot Pressing and conventional casting. The high wear and mechanical performance of 316L Stainless Steel fabricated by Selective Laser Melting are mainly due to the finer microstructure, induced by the process. In this sense, Selective Laser Melting seems a promising method to fabricate customized 316L SS implants with improved mechanical and wear performance
- 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.
- 3D Photo-Fabrication for Tissue Engineering and Drug DeliveryPublication . Brás Pereira, Rúben Filipe; Bartolo, PauloThe most promising strategies in tissue engineering involve the integration of a triad of biomaterials, living cells, and biologically active molecules to engineer synthetic environments that closely mimic the healing milieu present in human tissues, and that stimulate tissue repair and regeneration. To be clinically effective, these environments must replicate, as closely as possible, the main characteristics of the native extracellular matrix (ECM) on a cellular and subcellular scale. Photo-fabrication techniques have already been used to generate 3D environments with precise architectures and heterogeneous composition, through a multi-layer procedure involving the selective photocrosslinking reaction of a light-sensitive prepolymer. Cells and therapeutic molecules can be included in the initial hydrogel precursor solution, and processed into 3D constructs. Recently, photo-fabrication has also been explored to dynamically modulate hydrogel features in real time, providing enhanced control of cell fate and delivery of bioactive compounds. This paper focuses on the use of 3D photo-fabrication techniques to produce advanced constructs for tissue regeneration and drug delivery applications. State-of-the-art photo-fabrication techniques are described, with emphasis on the operating principles and biofabrication strategies to create spatially controlled patterns of cells and bioactive factors. Considering its fast processing, spatiotemporal control, high resolution, and accuracy, photo-fabrication is assuming a critical role in the design of sophisticated 3D constructs. This technology is capable of providing appropriate environments for tissue regeneration, and regulating the spatiotemporal delivery of therapeutics.
- 3D printed poly(E-caprolactone)/Hydroxyapatite scaffolds for bone tissue engineering: A comparative study on a Composite Preparation by Melt blending or solvent casting techniques and the influence of bioceramic content on scaffold propertiesPublication . Biscaia, Sara; Branquinho, Mariana V.; Alvites, Rui D.; Fonseca, Rita; Sousa, Ana Catarina; Pedrosa, Sílvia Santos; Caseiro, Ana R.; Guedes, Fernando; Patrício, Tatiana; Viana, Tânia; Mateus, Artur; Maurício, Ana C.; Alves, NunoBone tissue engineering has been developed in the past decades, with the engineering of bone substitutes on the vanguard of this regenerative approach. Polycaprolactone-based scaffolds are fairly applied for bone regeneration, and several composites have been incorporated so as to improve the scaffolds’ mechanical properties and tissue in-growth. In this study, hydroxyapatite is incorporated on polycaprolactone-based scaffolds at two different proportions, 80:20 and 60:40. Scaffolds are produced with two different blending methods, solvent casting and melt blending. The prepared composites are 3D printed through an extrusion-based technique and further investigated with regard to their chemical, thermal, morphological, and mechanical characteristics. In vitro cytocompatibility and osteogenic differentiation was also assessed with human dental pulp stem/stromal cells. The results show the melt-blending-derived scaffolds to present more promising mechanical properties, along with the incorporation of hydroxyapatite. The latter is also related to an increase in osteogenic activity and promotion. Overall, this study suggests polycaprolactone/hydroxyapatite scaffolds to be promising candidates for bone tissue engineering, particularly when produced by the MB method.
- 3D printing of new biobased unsaturated polyesters by microstereo-thermal-lithographyPublication . Gonçalves, Filipa A. M. M.; Costa, Cátia S. M. F.; Fabela, Inês G. P.; Farinha, Dina; Faneca, Henrique; Simões, Pedro N.; Serra, Arménio C.; Bártolo, Paulo J.; Coelho, Jorge F. J.New micro three-dimensional (3D) scaffolds using biobased unsaturated polyesters (UPs) were prepared by microstereo-thermal-lithography (μSTLG). This advanced processing technique offers indubitable advantages over traditional printing methods. The accuracy and roughness of the 3D structures were evaluated by scanning electron microscopy and infinite focus microscopy, revealing a suitable roughness for cell attachment. UPs were synthesized by bulk polycondensation between biobased aliphatic diacids (succinic, adipic and sebacic acid) and two different glycols (propylene glycol and diethylene glycol) using fumaric acid as the source of double bonds. The chemical structures of the new oligomers were confirmed by proton nuclear magnetic resonance spectra, attenuated total reflectance Fourier transform infrared spectroscopy and matrix assisted laser desorption/ionization-time of flight mass spectrometry. The thermal and mechanical properties of the UPs were evaluated to determine the influence of the diacid/glycol ratio and the type of diacid in the polyester's properties. In addition an extensive thermal characterization of the polyesters is reported. The data presented in this work opens the possibility for the use of biobased polyesters in additive manufacturing technologies as a route to prepare biodegradable tailor made scaffolds that have potential applications in a tissue engineering area.
- 3D shape prior active contours for an automatic segmentation of a patient specific femur from a CT scanPublication . Almeida, D.; Folgado, J.; Fernandes, P.R.; Ruben, RuiThe following paper describes a novel approach to a medical image segmentation problem. The fully automated computational procedure receives as input images from CT scan exams of the human femur and returns a three dimensional representation of the bone. This patient specific iterative approach is based in 3D active contours without edges, implemented over a level set framework, on which the evolution of the contour depends on local image parameters which can easily be defined by the user but also on a priori information about the volume to segment. This joint approach will lead to an optimal solution convergence of the iterative method. The resulting point cloud can be an excellent starting point for a Finite Element mesh generation and analysis or the basis for a stereolitography for example.
- 3D-printed teeth in endodontics: Why, how, problems and future: A narrative reviewPublication . Reis, Tiago; Barbosa, Cláudia; Franco, Margarida; Baptista, Catarina; Alves, Nuno; Castelo-Baz, Pablo; Martín-Cruces, José; Martin-Biedma, BenjaminThree-dimensional printing offers possibilities for the development of new models in endodontics. Numerous studies have used 3D-printed teeth; however, protocols for the standardization of studies still need to be developed. Another problem with 3D-printed teeth is the different areas of literature requested to understand the processes. This review aims to gather evidence about 3Dprinted teeth on the following aspects: (1) why they are advantageous; (2) how they are manufactured; (3) problems they present; and (4) future research topics. Natural teeth are still the standard practice in ex vivo studies and pre-clinical courses, but they have several drawbacks. Printed teeth may overcome all limitations of natural teeth. Printing technology relies on 3D data and post-processing tools to form a 3D model, ultimately generating a prototype using 3D printers. The major concerns with 3D-printed teeth are the resin hardness and printing accuracy of the canal anatomy. Guidance is presented for future studies to solve the problems of 3D-printed teeth and develop well-established protocols, for the standardization of methods to be achieved. In the future, 3D-printed teeth have the possibility to become the gold standard in ex vivo studies and endodontic training.
- 45S5 BAG-Ti6Al4V structures: The influence of the design on some of the physical and chemical interactions that drive cellular responsePublication . Melo-Fonseca, F.; Lima, R.; Costa, M.M.; Bartolomeu, F.; Alves, Nuno; Miranda, A.; Gasik, M.; Silva, F.S.; Silva, N.A.; Miranda, G.Multi-material Ti6Al4V cellular structures impregnated with 45S5 bioactive glass were designed and produced using Selective LaserMelting (SLM), an additive manufacturing technique, combinedwith Press and Sintering focusing on load bearing components like hip implants. These structures were designed to combine Ti6Al4V mechanical properties and promote bone ingrowth into the structure as the bioactive material (45S5) is being absorbed and replaced by newly formed bone. The influence of these structures design on some of the physical and chemical aspects that drive cellular response was assessed. Roughness, wettability, bioactive glass quantity and quality on the structures after processing and the pH measured during cell culture (as a consequence of bioactive glass dissolution) were evaluated and correlated with cellular viability, cellular distribution, morphology and proliferation on the surface and inside the structures.
- Adaptive Platforms and Flexible Deposition System for Big Area Additive Manufacturing (BAAM)Publication . Silva, Ruben; Sereno, Pedro; Mateus, Artur; Mitchell, Geoffrey; José da Silva Carreira, Pedro; Santos, Cyril; Vitorino, João; Domingues, JorgeThe interest around the additive manufacturing is increasing, with more and more solutions at both the industrial and desktop levels. As this is still a relatively recent issue for several industrial areas, there is a clear opportunity to explore in order to optimize the systems in the face of the needs of these same industries, and with increasing times, there are increasing factors to take into ac- count in initial phases of new product development. Presently, there is also a growing ecological awareness, with the concern of implementing a logic of waste reduction and implementation of the circular economy in new products with a view to the valuation of new alternative materials. With the development of solutions aimed at the optimization and feasibility of large additive manufacturing systems, the introduction of new alternative materials will be a reality, presenting in this article a solution and methodology for future tests for new materials. Thus, herein is studied a way of responding to both problems, new ecological materials and BAAM system optimization, presented through a hybrid and flexible solution based on the Pin Bed Forming principle applied to Big Area Additive Manufacturing systems.
- Additive manufactured Poly("-caprolactone)-graphene scaffolds: Lamellar crystal orientation, mechanical properties and biological performancePublication . Biscaia, Sara; Silva, João C.; Moura, Carla; Viana, Tânia; Tojeira, Ana; Mitchell, Geoffrey R.; Pascoal-Faria, Paula; Ferreira, Frederico Castelo; Alves, NunoUnderstanding the mechano–biological coupling mechanisms of biomaterials for tissue engineering is of major importance to assure proper scaffold performance in situ. Therefore, it is of paramount importance to establish correlations between biomaterials, their processing conditions, and their mechanical behaviour, as well as their biological performance. With this work, it was possible to infer a correlation between the addition of graphene nanoparticles (GPN) in a concentration of 0.25, 0.5, and 0.75% (w/w) (GPN0.25, GPN0.5, and GPN0.75, respectively) in three-dimensional poly("-caprolactone) (PCL)-based scaffolds, the extrusion-based processing parameters, and the lamellar crystal orientation through small-angle X-ray scattering experiments of extruded samples of PCL and PCL/GPN. Results revealed a significant impact on the scaffold’s mechanical properties to a maximum of 0.5% of GPN content, with a significant improvement in the compressive modulus of 59 MPa to 93 MPa. In vitro cell culture experiments showed the scaffold’s ability to support the adhesion and proliferation of L929 fibroblasts (fold increase of 28, 22, 23, and 13 at day 13 (in relation to day 1) for PCL, GPN0.25, GPN0.5, and GPN0.75, respectively) and bone marrow mesenchymal stem/stromal cells (seven-fold increase for all sample groups at day 21 in relation to day 1). Moreover, the cells maintained high viability, regular morphology, and migration capacity in all the different experimental groups, assuring the potential of PCL/GPN scaffolds for tissue engineering (TE) applications.