1,721,703 research outputs found
3D printing of hierarchical scaffolds based on mesoporous bioactive glasses (MBGs)-fundamentals and applications
Full text linkThe advent of mesoporous bioactive glasses (MBGs) in applied bio-sciences led to the birth of a new class of nanostructured materials combining triple functionality, that is, bone-bonding capability, drug delivery and therapeutic ion release. However, the development of hierarchical three-dimensional (3D) scaffolds based on MBGs may be difficult due to some inherent drawbacks of MBGs (e.g., high brittleness) and technological challenges related to their fabrication in a multiscale porous form. For example, MBG-based scaffolds produced by conventional porogen-assisted methods exhibit a very low mechanical strength, making them unsuitable for clinical applications. The application of additive manufacturing techniques significantly improved the processing of these materials, making it easier preserving the textural and functional properties of MBGs and allowing stronger scaffolds to be produced. This review provides an overview of the major aspects relevant to 3D printing of MBGs, including technological issues and potential applications of final products in medicine
Modelling the elastic mechanical properties of bioactive glass-derived scaffolds
Full text linkPorosity is known to play a pivotal role in dictating the functional properties of biomedical scaffolds, with special reference to mechanical performance. While compressive strength is relatively easy to be experimentally assessed even for brittle ceramic and glass foams, elastic properties are much more difficult to be reliably estimated. Therefore, describing and, hence, predicting the relationship between porosity and elastic properties based only on the constitutive parameters of the solid material is still a challenge. In this work, we quantitatively compare the predictive capability of a set of different models in describing, over a wide range of porosity, the elastic modulus (7 models), shear modulus (3 models) and Poisson's ratio (7 models) of bioactive silicate glass-derived scaffolds produced by foam replication. For these types of biomedical materials, the porosity dependence of elastic and shear moduli follows a second-order power-law approximation, whereas the relationship between porosity and Poisson's ratio is well fitted by a linear equation
Multiple and promising applications of strontium (Sr)-containing bioactive glasses in bone tissue engineering
Full text linkItaliani e “slavi” a Fiume e sul confine orientale italiano
No full textRassegna lavori su Fiume e Confine orientale italiano e prospettive di ricerca
A guided walk through the world of mesoporous bioactive glasses (MBGs): Fundamentals, processing, and applications
Full text linkBioactive glasses (BGs) are traditionally known to be able to bond to living bone and stimulate bone regeneration. The production of such materials in a mesoporous form allowed scientists to dramatically expand the versatility of oxide-based glass systems as well as their applications in biomedicine. These nanostructured materials, called mesoporous bioactive glasses (MBGs), not only exhibit an ultrafast mineralization rate but can be used as vehicles for the sustained delivery of drugs, which are hosted inside the mesopores, and therapeutic ions, which are released during material dissolution in contact with biological fluids. This review paper summarizes the main strategies for the preparation of MBGs, as well as their properties and applications in the biomedical field, with an emphasis on the methodological aspects and the promise of hierarchical systems with multiscale porosity
Digital light processing of ceria-stabilized zirconia: Role of powder pre-treatment on printability and physico-mechanical properties
Full text linkIn this study, the role of pre-treatment of a ceria-stabilized zirconia powder on slurry printability in Digital Light Processing as well as on density, microstructural features and flexural strength of the sintered materials was investigated. Three powder batches, namely un-milled, ball-milled, and ball-milled and thermally post-treated were compared. Ball-milling induced tetragonal-to-monoclinic phase transformation and the appearance of oxygen vacancies. The thermal post-treatment was effective in restoring a higher tetragonal phase content and the starting cerium oxidation state. Slurries with a fixed solid loading (41 vol%) and variable amounts of dispersant were prepared. Different curing behaviors and, consequently, different qualities of the printed parts were observed. The milled and thermally treated powder was used to produce high-density sintered materials characterized by submicrometric grains (≅ 600 nm) and high flexural strength (≅ 560 MPa)
Sintering behavior of a six-oxide silicate bioactive glass for scaffold manufacturing
Full text linkThe intrinsic brittleness of bioactive glasses (BGs) is one of the main barriers to the widespread use of three-dimensional porous BG-derived bone grafts (scaffolds) in clinical practice. Among all the available strategies for improving the mechanical properties of BG-based scaffolds, strut densification upon sintering treatments at high temperatures represents a relatively easy approach, but its implementation might lead to undesired and poorly predictable decrease in porosity, mass transport properties and bioactivity resulting from densification and devitrification phenomena occurring in the material upon heating. The aim of the present work was to investigate the sinter-crystallization of a highly bioactive SiO2-P2O5-CaO–MgO–Na2O–K2O glass (47.5B composition) in reference to its suitability for the fabrication of bonelike foams. The thermal behavior of 47.5B glass particles was investigated upon sintering at different temperatures in the range of 600–850◦C by means of combined thermal analyses (differential thermal analysis (DTA) and hot-stage microscopy (HSM)). Then, XRD measurements were carried out to identify crystalline phases developed upon sintering. Finally, porous scaffolds were produced by a foam replica method in order to evaluate the effect of the sintering temperature on the mechanical properties under compression loading conditions. Assessing a relationship between mechanical properties and sintering temperature, or in other words between scaffold performance and fabrication process, is a key step towards the rationale design of optimized scaffolds for tissue repair
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