Synthesis by solid route and physicochemical characterizations of blends of calcium orthophosphate powders and mesoporous silicon particles

The purpose of the study was to investigate the synthesis of economic calcium phosphate powders from recycled oyster shells, using a ball milling method. The oyster shell powder and a calcium pyrophosphate powder were used as starting materials and ball milled, then heat treated at 1,050°C for 5 h to produce calcium phosphate powders through a solid-state reaction. Electrochemically synthesized mesoporous silicon microparticles were then added to the prepared phosphate powders by mechanical mixer. The final powders were characterized using X-ray diffraction, Fourier transform infrared spectroscopy, and scanning electron microscopy to analyze their chemical composition and determine the most suitable process conditions. The biocompatibility of the produced powders was also tested in vitro using murine cells and the results showed good biocompatibility

Développement de céramiques pour l'ingénierie tissulaire osseuse : de la synthèse de matériaux à l’évaluation biologique

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Calcium phosphate bioceramics: From cell behavior to chemical-physical properties

International audienceCalcium phosphate ceramics, including hydroxyapatite (HA), have been used as bone substitutes for more than 40 years. Their chemical composition, close to that of the bone mineral, confers them good biological and physical properties. However, they are not sufficient to meet all the needs in bone regenerative medicine, such as in the context of critical bone lesions. Therefore, it is essential to improve their biological performances in order to extend their application domains. In this aim, three approaches are mainly followed on the assumption that the biological response can be tuned by modifications of the chemical physical properties of the ceramic: 1) Incorporation of specific chemical species into the calcium phosphate crystalline lattice of chemical elements to stimulate bone repair. 2) Modulation of the bioceramic architecture to optimize the cellular responses at the interface. 3) Functionalization of the bioceramic surface with bioactive molecules. These approaches are supposed to act on separate parameters but, as they are implemented during different steps of the ceramic processing route, they cannot be considered as exclusive. They will ineluctably induces changes of several other physical chemical properties of the final ceramic that may also affect the biological response. Using examples of recent works from our laboratory, the present paper aims to describe how biology can be affected by the bioceramics modifications according to each one of these approaches. It shows that linking biological and chemical physical data in a rational way makes it possible to identify pertinent parameters and related processing levers to target a desired biological response and then more precisely tune the biological performance of ceramic biomaterials. This highlights the importance of integrating the biological evaluation into the heart of the processes used to manufacture optimized biomaterials

La transdisciplinarité au service de la conception d’implants innovants éphémères

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Des matériaux céramiques pour réparer l’os : Comprendre l’interaction des cellules avec leur environnement pour créer des substituts osseux innovants

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Élaboration de biomatériaux céramiques optimisés pour l’ingénierie tissulaire osseuse

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New Approach to Identify the Physiological State of Bone Cells at the Surface of Hydroxyapatite Bioceramics

The aim of this work was to identify robust and reproducible signatures characterizing the different steps of bone cell differentiation, from precursors to mature bone cells, using approaches allowing characterization by label-free imaging. Human mesenchymal stromal cells (hMSCs) were cultured either in a growth medium (GM), unable to induce cell differentiation by itself, or in an osteogenic differentiation medium (ODM) on hydroxyapatite ceramics or borosilicate glass. Cell density as well as cell structure, size, and morphology were investigated. A fluorescence microscopy-based approach was followed, using fluorescent labelling of cell features. Some early morphological changes of hMSC during osteogenic differentiation were identified as soon as 48h that were accentuated after 7 days of culture. Cell density was higher when cells were cultured in GM and the cells exhibited significantly smaller nuclei (size ratio about 1.3-1.5) than those cultured in ODM, regardless of the culture support. In ODM, the cells were also of bigger size (1.2 to 1.5 times) and their focal adhesions were reinforcedType I collagen, a gold standard marker of osteogenic differentiation, appeared more intense in ODM. These cell features can be determined using multimodal label-free imaging methods to characterize the differentiation state of hMSCs at the biomaterial surface. They give rise to new cost-effective approaches to investigate cell behavior by suppressing the chemical markers and reducing both the number of needed samples and the requested time to do so

Influence of copper-substitution in calcium phosphate ceramics on endothelial cells

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