Nanocrystalline apatites: The fundamental role of water

Drouet, Christophe; Aufray, Maëlenn; Rollin-Martinet, Sabrina; Vandecandelaere, Nicolas; Grossin, David; Rossignol, Fabrice; Champion, Éric; Navrotsky, Alexandra; Rey, Christian

doi:10.2138/am-2018-6415

Cited by 49 publications

(56 citation statements)

References 79 publications

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“…3) the proportion of surface layer appears more important in BNA than in CDHA. This result also agrees with the synthesis conditions (maturation at 37°C during 30 min for CDHA and only 22°C for 5 min for BNA), the higher the maturation time and temperature are, the thinner is the non apatitic hydrated surface layer [7]. The crystalline core is a calcium (and hy droxide) deficient apatite which contains apatitic hydrogenphosphate ions (Fig.…”

Section: Discussionsupporting

confidence: 87%

“…environments and the nanosized dimensions of the crystals [21]. In the consolidation process of ceramics at such low temperature, the role of the hydrated layer is thought to be primordial: the ions contained in the hydrated layer being indeed highly labile, ion diffusion through hy drated layers of adjacent nanocrystals can occur even without strong thermal activation [7]. Recently, we investigated consolidation of bone like carbonated calcium phosphates by SPS at low temperature and showed that the sinterability was greatly enhanced when amorphous carbonated calcium phosphate (ACPs) powders were used in compar ison with nanocrystalline ones [23].…”

Section: Spark Plasma Sinteringmentioning

confidence: 99%

“…Studies have also re vealed the existence of Jess organized ionic environments on the surface of the nanocrystals, known as non apatitic environments as they do not correspond to the regular apatitic structure [3 6). This layer is sig nificantly hydrated, and the presence of water is thought to explain in part the reactivity of the nanocrystals [7 ). These environments are lo cated on the surface of the apatite nanocrystals constituting both the minerai part of the bone [ 6,8) and biominletic synthetic analogs pro vided that close to physiolo gi cal conditions are used for their preparation.…”

Section: Introductionmentioning

confidence: 99%

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Influence of carbonation on the low-temperature consolidation by Spark Plasma Sintering of carbonated calcium phosphate bioceramics

Ortali

Julien

Drouet

et al. 2020

Ceramics International

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Section: Discussionsupporting

confidence: 87%

Section: Spark Plasma Sinteringmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Influence of carbonation on the low-temperature consolidation by Spark Plasma Sintering of carbonated calcium phosphate bioceramics

Ortali

Julien

Drouet

et al. 2020

Ceramics International

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“…The strongly bound water molecules are very likely to form a rigid hydration shell around the bone mineral platelets such that their largest side faces are not in direct contact with each other. As for trapped water molecules, they presumably form hydration spheres around the surface ions in a configuration that is reminiscent of that of the ions prior to their incorporation into the solid phase [52]. These results give rise to the question of whether this incorporation of water molecules into the surface could be the origin of the amorphisation of the outer surface of bone mineral nanoparticles.…”

Section: Discussionmentioning

confidence: 99%

“…Our results, therefore, suggest that, in wet conditions, a large quantity of water molecules is not only strongly bound to but is also trapped within the amorphous surface layer. Since the arrangement of ions/molecules within the amorphous surface layer is sometimes seen as a reminiscence of the state in which the ions/molecules were prior to their incorporation into the solid phase [52], we can assume that these additional trapped water molecules form hydration spheres around the surface ions. Hence, the trapped water molecules might be part of the first hydration sphere of the surface ions, while the bound water molecules might be part of the second or third hydration sphere of the surface ions.…”

Section: −mentioning

confidence: 99%

Organization of Bone Mineral: The Role of Mineral–Water Interactions

et al. 2018

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The mechanism (s) that drive the organization of bone mineral throughout the bone extracellular matrix remain unclear. The long-standing theory implicates the organic matrix, namely specific non-collagenous proteins and/or collagen fibrils, while a recent theory proposes a self-assembly mechanism. Applying a combination of spectroscopic and microscopic techniques in wet and dry conditions to bone-like hydroxyapatite nanoparticles that were used as a proxy for bone mineral, we confirm that mature bone mineral particles have the capacity to self-assemble into organized structures. A large quantity of water is present at the surface of bone mineral due to the presence of a hydrophilic, amorphous surface layer that coats bone mineral nanoparticles. These water molecules must not only be strongly bound to the surface of bone mineral in the form of a rigid hydration shell, but they must also be trapped within the amorphous surface layer. Cohesive forces between these water molecules present at the mineral–mineral interface not only hold the mature bone mineral particles together, but also promote their oriented stacking. This intrinsic ability of mature bone mineral particles to organize themselves without recourse to the organic matrix forms the foundation for the development of the next generation of orthopedic biomaterials.

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Structure and Surface Study of Hydroxyapatite‐Based Materials

Costentin

Drouet

Salles

et al. 2022

Design and Applications of Hydroxyapatite‐Based Catalysts

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In addition to designing catalytic materials ever more active and selective, the emergence of new classes of greener catalysts remains very challenging. The apatite family system with hydroxyapatite (HA) structure appears as a good candidate for catalysis due to its ecocompatibility properties, its sorption ability toward organic molecules, and its tunable composition resulting into modulation of its surface properties. Depending on their mode of preparation, these inexpensive and environment-friendly apatitic calcium phosphates exhibit properties of relevance to catalysis, such as large surface area and various morphologies.However, most studies focused so far on the catalytic performance of these compounds, while the study of structure-reactivity relationships required for rationalized optimization remains rather limited. This chapter aims at providing tools to help understand the catalytic behavior of apatite compounds, giving details about their structure, surface properties, and reactivity; this will include both stoichiometric and nonstoichiometric compounds, sometimes biomimetic and potentially substituted. A special attention is dedicated to recent advances in the characterization of their structural properties (bulk and surface/interphase) that have a strong impact on their reactivity, through both experimental and computational approaches to study the mechanisms occurring in the structure or at the crystals surface, as well as thermodynamic and dynamical properties. Remaining characterization challenges for apatite-based catalysts will also be discussed. 1.an influence on the charges carried by the cation and on the related strength of the Ca-O interaction [127], which results in different adsorption properties with guest molecules. To go further, quantum calculations coupled with NMR (Nuclear Magnetic Resonance) resultsshowed the impact of the presence of OHions on the migration of Ca 2+ as well as the rotation of PO4 3groups [128]. In the hydroxyapatite structure, phosphate ions PO4 3are the largest components of the structure. As such, they provide a primary backbone via 3D compact-like piling, generating interstitial sites for the other ions of the structure. Metal cations such as Ca 2+ occupy two types of crystallographic sites, denoted Ca1 (4 sites per unit formula) and Ca2 (6 sites per unit formula), see Figure 2. Ca1 sites are localized along the trigonal axis with the coordinates (1/4, 3/4, 1/2) and (3/4, 1/4, 1/2), forming linear columns along the c-axis. Ca2 sites in contrast form equilateral triangles at z = 1/4 and z = 3/4 on the sixfold screw (senary) 63 axes. Adjacent Ca1 and Ca2 sites are linked through shared oxygen atoms from PO4 tetrahedra. Ca1 sites generate (distorted) polyhedra where the metal ion is in ninefold coordination, while in Ca2 sites it is in sevenfold coordination.The Ca2 triangles contribute to delimit so-called "apatitic channels" where ions such as OHare axially located (Figure 3) [116,120]. In calcium hydroxyapatite, the Ca2 triangular sites correspond to the narrow...

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Nanocrystalline apatites: The fundamental role of water

Abstract: OATAO is an open access repository that collects the work of some Toulouse researchers and makes it freely available over the web where possible.

Cited by 49 publications

References 79 publications

Influence of carbonation on the low-temperature consolidation by Spark Plasma Sintering of carbonated calcium phosphate bioceramics

Influence of carbonation on the low-temperature consolidation by Spark Plasma Sintering of carbonated calcium phosphate bioceramics

Organization of Bone Mineral: The Role of Mineral–Water Interactions

Structure and Surface Study of Hydroxyapatite‐Based Materials

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