Porous bodies of hydroxyapatite produced by a combination of the gel-casting and polymer sponge methods

Ocampo, Jazmín González; Sierra, Diana; Orozco, Claudia Patricia Ossa

doi:10.1016/j.jare.2015.06.006

Cited by 42 publications

(14 citation statements)

References 20 publications

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“…Aunque el tamaño de poro obtenido es pequeño, los valores alcanzados se encuentran dentro de los rangos reportados por autores como Boccaccini [19], Hutmacher [20], Kim [21] y González [22,23], quienes obtuvieron porcentajes de porosidad entre 40 y 92% para cuerpos porosos preparados con 50 y 60% de sólidos, demostrando que el recubrimiento realizado tiene influencia en este parámetro, ya que se observa una disminución en la interconectividad a medida que aumenta la concentración de quitosano y el tiempo de inmersión.…”

Section: Resultsunclassified

Evaluacion de recubrimientos de quitosano sobre cuerpos porosos de hidroxiapatita

Sierra

Ospina

2019

Sci. tech

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Los defectos óseos han sido tratados implantando tejidos autólogos o alogénicos, sin embargo, el éxito de estos implantes depende de la biocompatibilidad, fijación con el tejido, características físicoquímicas y las complicaciones vinculadas al uso de injertos, como la limitada cantidad de hueso a extraer, la morbilidad en el lugar de extracción y los potenciales riesgos por infección; por ello, surge la Ingeniería de Tejidos, donde las propiedades superficiales y mecánicas de los biomateriales empleados juegan un papel importante en la interacción materialtejido. En esta investigación se desarrollaron cuerpos porosos de hidroxiapatita por gel-casting y se recubrieron con quitosano a diferentes concentraciones, con el fin de verificar la influencia del recubrimiento en las propiedades mecánicas y de estabilidad de los cuerpos fabricados, comparándolas con las del hueso para intentar mejorar los requerimientos de los implantes. Para ello, se evaluó la morfología del poro, la resistencia a la compresión y la degradabilidad de los cuerpos con y sin recubrimiento. Los resultados mostraron que se logra mejorar las propiedades y la estabilidad en condiciones fisiológicas, lo que los hace aptos para usar en regeneración de tejido óseo.

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Section: Resultsunclassified

Evaluacion de recubrimientos de quitosano sobre cuerpos porosos de hidroxiapatita

Sierra

Ospina

2019

Sci. tech

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“…This condition is verified when the foam is wet, i.e., with a liquid fraction above 30%. This range of liquid fraction is a relevant regime for a wide variety of industrial applications: For instance, it is the case in many food products [35], such as ice cream [36], but also for metallic [37] or polymeric [38] foams, or cellular concrete [39]. In such foams, the spherical bubbles experience a dissolution pressure ΔP foam that depends on their own size, compared to an effective size representing the surrounding foam.…”

Section: Generalization To a Foammentioning

confidence: 99%

Probing the Mechanical Strength of an Armored Bubble and Its Implication to Particle-Stabilized Foams

et al. 2016

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International audienceBubbles are dynamic objects that grow and rise or shrink and disappear, often on the scale of seconds. This conflicts with their uses in foams where they serve to modify the properties of the material in which they are embedded. Coating the bubble surface with solid particles has been demonstrated to strongly enhance the foam stability, although the mechanisms for such stabilization remain mysterious. In this paper, we reduce the problem of foam stability to the study of the behavior of a single spherical bubble coated with a monolayer of solid particles. The behavior of this armored bubble is monitored while the ambient pressure around it is varied, in order to simulate the dissolution stress resulting from the surrounding foam. We find that above a critical stress, localized dislocations appear on the armor and lead to a global loss of the mechanical stability. Once these dislocations appear, the armor is unable to prevent the dissolution of the gas into the surrounding liquid, which translates into a continued reduction of the bubble volume, even for a fixed overpressure. The observed route to the armor failure therefore begins from localized dislocations that lead to large-scale deformations of the shell until the bubble completely dissolves. The critical value of the ambient pressure that leads to the failure depends on the bubble radius, with a scaling of ΔPcollapse∝R−1, but does not depend on the particle diameter. These results disagree with the generally used elastic models to describe particle-covered interfaces. Instead, the experimental measurements are accounted for by an original theoretical description that equilibrates the energy gained from the gas dissolution with the capillary energy cost of displacing the individual particles. The model recovers the short-wavelength instability, the scaling of the collapse pressure with bubble radius, and the insensitivity to particle diameter. Finally, we use this new microscopic understanding to predict the aging of particle-stabilized foams, by applying classical Ostwald ripening models. We find that the smallest armored bubbles should fail, as the dissolution stress on these bubbles increases more rapidly than the armor strength. Both the experimental and theoretical results can readily be generalized to more complex particle interactions and shell structures

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“…These are usually classified in three main processing strategies: replication, direct foaming, and sacrificial templating [11]. Replication [12] consists of impregnating or infiltrating a template with highly dispersed ceramic suspensions. Upon sintering, the template is removed and a positive replica of it is obtained.…”

Section: Introductionmentioning

confidence: 99%

Processing of Macroporous Alumina Ceramics Using Pre-Expanded Polymer Microspheres as Sacrificial Template

Oset

Nordin²,

Akhtar

2018

Ceramics

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Shaped porous ceramics have proven to be the most adapted materials for several industrial applications, both at low and high temperatures. Recent research has been focused on developing shaping techniques, allowing for a better control over the total porosity and the pores characteristics. In this study, macroporous alumina foams were fabricated by gel-casting using pre-expanded polymeric microspheres with average sizes of 40 μm, 20 μm, and 12 μm as sacrificial templates. The gel-casting method, as well as the drying, debinding, and presintering conditions were investigated and optimized to process mechanically strong and highly porous alumina scaffolds. Furthermore, a reliable model relating the amount of pre-expanded polymeric microspheres and the total porosity of the presintered foams was developed and validated by mercury intrusion porosimetry measurements. The electron microscopy investigation of the presintered foams revealed that the size distribution and the shape of the pores could be tailored by controlling the particle size distribution and the shape of the wet pre-expanded microspheres. Highly uniform and mechanically stable alumina foams with bimodal porosity ranging from 65.7 to 80.2 vol. % were processed, achieving compressive strengths from 3.3 MPa to 43.6 MPa. Given the relatively open pore structure, the pore size distribution, the presintered mechanical strength, and the high porosity achieved, the produced alumina foams could potentially be used as support structures for separation, catalytic, and filtration applications.

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Porous bodies of hydroxyapatite produced by a combination of the gel-casting and polymer sponge methods

Cited by 42 publications

References 20 publications

Evaluacion de recubrimientos de quitosano sobre cuerpos porosos de hidroxiapatita

Evaluacion de recubrimientos de quitosano sobre cuerpos porosos de hidroxiapatita

Probing the Mechanical Strength of an Armored Bubble and Its Implication to Particle-Stabilized Foams

Processing of Macroporous Alumina Ceramics Using Pre-Expanded Polymer Microspheres as Sacrificial Template

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