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Leite A.J.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Leite A.J.,Pt Government Assoct Laboratory | Caridade S.G.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Caridade S.G.,Pt Government Assoct Laboratory | And 2 more authors.
Journal of Non-Crystalline Solids | Year: 2016

Chitosan (CHT) spheres incorporating bioactive glass nanoparticles (BGNPs) were prepared to obtain a composite system able to induce the deposition of an apatite layer upon immersion in a biological-like environment. Spheres were synthesized with different concentrations of BGNPs obtained from a sol-gel route and genipin (GNP, the crosslinking agent). Biomimetic superhydrophobic surfaces were used to support droplets of chitosan-based solutions that after crosslinking enabled to produce well developed spherical particles with controlled sizes. From SEM and EDS analysis it was observed the successful formation of bone-like apatite on the surface when the spheres were immersed in a simulated body fluid (SBF). Lower GNP concentration promoted more apatite formation. The spheres presented shape memory behaviour triggered by hydration with high values of shape fixity and shape recovery. This effect was used to introduce these spheres in a bone defect showing a good geometrical accommodation in the implanted site. The bioactive spheres allowed the incorporation of a drug model and its effective release. Overall the developed nanocomposite spheres showed great potential for bone tissue engineering in particular as a device to be implanted using minimal invasive procedures. © 2015 Elsevier B.V. Source


Moreira A.H.J.,Pt Government Assoct Laboratory | Moreira A.H.J.,University of Minho | Moreira A.H.J.,Polytechnic Institute of Cavado and Ave | Queiros S.,Pt Government Assoct Laboratory | And 11 more authors.
Progress in Biomedical Optics and Imaging - Proceedings of SPIE | Year: 2015

The success of dental implant-supported prosthesis is directly linked to the accuracy obtained during implant's pose estimation (position and orientation). Although traditional impression techniques and recent digital acquisition methods are acceptably accurate, a simultaneously fast, accurate and operator-independent methodology is still lacking. Hereto, an image-based framework is proposed to estimate the patient-specific implant's pose using cone-beam computed tomography (CBCT) and prior knowledge of implanted model. The pose estimation is accomplished in a threestep approach: (1) a region-of-interest is extracted from the CBCT data using 2 operator-defined points at the implant's main axis; (2) a simulated CBCT volume of the known implanted model is generated through Feldkamp-Davis-Kress reconstruction and coarsely aligned to the defined axis; and (3) a voxel-based rigid registration is performed to optimally align both patient and simulated CBCT data, extracting the implant's pose from the optimal transformation. Three experiments were performed to evaluate the framework: (1) an in silico study using 48 implants distributed through 12 tridimensional synthetic mandibular models; (2) an in vitro study using an artificial mandible with 2 dental implants acquired with an i-CAT system; and (3) two clinical case studies. The results shown positional errors of 67±34μm and 108μm, and angular misfits of 0.15±0.08 and 1.4, for experiment 1 and 2, respectively. Moreover, in experiment 3, visual assessment of clinical data results shown a coherent alignment of the reference implant. Overall, a novel image-based framework for implants' pose estimation from CBCT data was proposed, showing accurate results in agreement with dental prosthesis modelling requirements. © 2015 SPIE. Source


Srisuk P.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | Srisuk P.,Pt Government Assoct Laboratory | Srisuk P.,Khon Kaen University | Correlo V.M.,European Institute of Excellence on Tissue Engineering and Regenerative Medicine | And 7 more authors.
Journal of Macromolecular Science, Part B: Physics | Year: 2015

Melanins are phenol-based pigments with the potential for widespread applications, including bioelectronics and tissue engineering. The concentration-dependent structural transition of sepia melanin in water is analyzed. This biopolymer at high concentration gives the well-known nanospheres, whereas sample dilution gives unforeseen nanofibres exhibiting the structural features of mature amyloid fibrils. We propose a mechanism of pigment self-assembly dependent on the interaction of residual melanosomal protein(s) with eumelanin heteropolymer. Our results contribute to understanding the peculiar physicochemical properties of this ubiquitous pigment. Copyright © Taylor & Francis Group, LLC. Source

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