Nanocrystalline hydroxyapatite with simultaneous enhancements in hardness and toughness

Wang, Jiwen; Shaw, Leon L.

doi:10.1016/j.biomaterials.2009.08.048

Cited by 156 publications

(120 citation statements)

References 48 publications

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“…Therefore, due to low grain growth rates, a low-temperature sintering appears to be effective to produce fine-grained apatite bioceramics [174]. Furthermore, the mechanical properties (namely, hardness and toughness) of HA bioceramics appeared to increase as the grain size decreased from sub-micrometers to nanometers [175].…”

Section: Micron-and Submicron-sized Calcium Orthophosphates Versus Thmentioning

confidence: 99%

Nanodimensional and Nanocrystalline Calcium Orthophosphates

Dorozhkin¹

2012

AJBE

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Nano-sized particles and crystals play an important role in the formation of calcified tissues of various animals. For example, nano-sized and nanocrystalline calcium orthophosphates in the form of apatites of biological origin represent the basic inorganic building blocks of bones and teeth of mammals. Namely, according the recent developments in biomineralization, tens to hundreds nanodimensional crystals of a biological apatite are self-assembled into these complex structures. This process occurs under a strict control by bioorganic matrixes. Furthermore, both a greater viability and a better proliferation of various types of cells have been detected on smaller crystals of calcium orthophosphates. Thus, the nano-sized and nanocrystalline forms of calcium orthophosphates have a great potential to revolutionize the hard tissue-engineering field, starting from bone repair and augmentation to controlled drug delivery systems. This review reports on current state of the art and recent developments on the subject, starting from synthesis and characterization to biomedical and clinical applications. Furthermore, the review also discusses possible directions for future research and development.

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Section: Micron-and Submicron-sized Calcium Orthophosphates Versus Thmentioning

confidence: 99%

Nanodimensional and Nanocrystalline Calcium Orthophosphates

Dorozhkin¹

2012

AJBE

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“…Thus, the presence of cuticles with nanospheres could impose an effective resistance to gas diffusion and represent a fitness cost to the maintenance of this eggshell trait. Additionally, hydroxyapatite or vaterite nanoparticles greatly increase fracture toughness of ceramics [62] by effectively deflecting crack propagation [63]. This suggests that nanospheres on cuticles might increase eggshell toughness and potentially hinder the hatching process for embryos with otherwise brittle eggshells [64].…”

Section: Discussionmentioning

confidence: 99%

The evolution of eggshell cuticle in relation to nesting ecology

et al. 2016

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Avian eggs are at risk of microbial infection prior to and during incubation. A large number of defence mechanisms have evolved in response to the severe costs imposed by these infections. The eggshell's cuticle is an important component of antimicrobial defence, and its role in preventing contamination by microorganisms in domestic chickens is well known. Nanometer-scale cuticular spheres that reduce microbial attachment and penetration have recently been identified on eggs of several wild avian species. However, whether these spheres have evolved specifically for antimicrobial defence is unknown. Here, we use comparative data on eggshell cuticular structure and nesting ecology to test the hypothesis that birds nesting in habitats with higher risk of infection (e.g. wetter and warmer) are more likely to evolve cuticular nanospheres on their eggshells than those nesting in less risky habitats. We found that nanostructuring, present in 54 of 296 analysed species, is the ancestral condition of avian eggshells and has been retained more often in taxa that nest in humid infection-prone environments, suggesting that they serve critical roles in antimicrobial egg defence.

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“…During the first step of two-step sintering, the pressed samples were always heated to the higher temperature in order to achieve sufficient activation energy for attaining of critical density, and temperature of the second step must be lower but sufficient to result with high density of materials without grain growth [28]. Noticeable improvements in the fracture toughness and hardness of HAP-based bioceramic materials were achieved through control of the grain size [24,29,30]. Decreasing in the grain size of HAP could additionally result in biocompatibility improvement of potential implant materials and improved cell attachment and their proliferation [31,32].…”

Section: Introductionmentioning

confidence: 99%

The influence of Sr and Mn incorporated ions on the properties of microwave single- and two-step sintered biphasic HAP/TCP bioceramics

et al. 2014

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The aims of this study were to investigate the effects of Sr-and Mn-doped ions on the sintering behaviors, microstructure and mechanical properties of the bioceramics processed by single-and two-step microwave sintering (MWSSS and MWTSS). Nano-sized calcium hydroxyapatite powders doped with Sr and Mn ions, obtained by modified precipitation synthesis, were isostatically pressed at 400 MPa and processed by MWSSS and MWTSS at different temperatures. In all cases during the sintering, the doped HAP powders turned into biphasic mixtures of HAP and TCP, but the amount of TCP was certainly lower in the case of MWTSS. It was shown that the doped ions significantly affected: density, microstructure, grain size, porosity, hardness, and fracture toughness of the processed bioceramics. Two-step microwave sintering was successfully applied for the processing of HAP/ TCP bioceramics doped with strontium and manganese ions. Both two-step microwave sintered doped bioceramics had similar and high hardness values, but the strontiumsubstituted bioceramic material certainly had higher fracture toughness (1.54 MPam 1/2 ), with an average grain size of 195 nm. Based on the results presented in this paper, it was concluded that the two-step microwave sintered strontium-doped bioceramics could be suitable materials in the bone regenerative field.

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Nanocrystalline hydroxyapatite with simultaneous enhancements in hardness and toughness

Cited by 156 publications

References 48 publications

Nanodimensional and Nanocrystalline Calcium Orthophosphates

Nanodimensional and Nanocrystalline Calcium Orthophosphates

The evolution of eggshell cuticle in relation to nesting ecology

The influence of Sr and Mn incorporated ions on the properties of microwave single- and two-step sintered biphasic HAP/TCP bioceramics

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