Structure and formation of amorphous calcium phosphate and its role as surface layer of nanocrystalline apatite: Implications for bone mineralization

Edén, Mattias

doi:10.1016/j.mtla.2021.101107

Cited by 57 publications

(66 citation statements)

References 390 publications

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“… 22 − 24 In addition, some other forms of doped apatite, such as fluor-carbonate hydroxyapatite, are found in fish enameloids. 25 Other biologically relevant CPCs are amorphous calcium phosphate (ACP), 26 , 27 monetite (dibasic calcium phosphate anhydrate, DCPA; CaHPO 4 ), 28 , 29 brushite (dibasic calcium phosphate dihydrate, DCPD; CaHPO 4 .2H 2 O), 30 octacalcium phosphate (OCP); Ca 8 H 2 (PO 4 ) 6 .H 2 O), 31 calcium pyrophosphate; Ca 2 P 2 O 7 ), 32 α-tricalcium phosphate (α-TCP), 33 β-tricalcium phosphate (β-TCP; Ca 3 (PO 4 ) 2 ), 34 and tetracalcium phosphate; Ca 4 (PO 4 ) 2 O). 35 Nevertheless, HA is not a resorbable form of CPC because the resorptive capacity of CPCs increases with their reduced crystallinity, such that ACP ≫ brushite > monetite > OCP > α-TCP ≫ β-TCP > HA.…”

Section: Introductionmentioning

confidence: 99%

Probing the Structure, Cytocompatibility, and Antimicrobial Efficacy of Silver-, Strontium-, and Zinc-Doped Monetite

Adawy

Dı́az

2022

ACS Appl. Bio Mater.

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Calcium phosphate phases are among the most widely accepted compounds for biomaterial applications, of which the resorbable phases have gained particular attention in recent years. Brushite and its anhydrous form monetite are among the most interesting resorbable calcium phosphate phases that can be applied as cements and for in situ fabrication of three-dimensional (3D) implants. Of these two dicalcium phosphate compounds, monetite is more stable and undergoes slower degradation than brushite. The purpose of the current study is to synthesize and dope monetite with the antimicrobial elements silver and zinc and the osteoinductive element strontium and investigate the possible structural variations as well as their biocompatibility and antimicrobial effectiveness. For this, powder X-ray diffraction (PXRD), energy-dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and cryo-transmission electron microscopy (cryo-TEM) were used to thoroughly study the synthesized structures. Moreover, the ASTM E-2149-01 protocol and a cell proliferation assay were used to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) and the cytocompatibility of the different phases with the Soas-2 cell line, respectively. The results confirm the successful synthesis and doping procedures, such that zinc was the most incorporated element into the monetite phase and strontium was the least incorporated element. The microbiological studies revealed that silver is a very effective antimicrobial agent at low concentrations but unsuitable at high concentrations because its cytotoxicity would prevail. On the other hand, doping the compounds with zinc led to a reasonable antimicrobial activity without compromising the biocompatibility to obviously high concentrations. The study also highlights that strontium, widely known for its osteoinductivity, bears an antimicrobial effect at high concentrations. The generated doped compounds could be beneficial for prospective studies as bone cements or for scaffold biomaterial applications.

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Section: Introductionmentioning

confidence: 99%

Probing the Structure, Cytocompatibility, and Antimicrobial Efficacy of Silver-, Strontium-, and Zinc-Doped Monetite

Adawy

Dı́az

2022

ACS Appl. Bio Mater.

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“…Compared to HAp nanoparticles synthesized in ordinary solvents, HAP nanoparticles synthesized in SBF show less crystallinity, implying that HAp nanoparticles grown in vivo may have less crystallinity. This is supported by studies of animal bones [38][39][40][41]. It is interesting to notice that in F-HAp synthesized in SBF and NaF, the crystallinity increased.…”

Section: Xrdmentioning

confidence: 57%

Varying Synthesis Conditions and Comprehensive Characterization of Fluorine-Doped Hydroxyapatite Nanocrystals in a Simulated Body Fluid

et al. 2022

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Bone supports animal bodies, is the place where blood is produced, and is essential for the immune system, among other important functions. The dominant inorganic component in bone is hydroxyapatite (Hap), the structure and dynamics of which still pose many unsolved puzzles. An updated understanding of HAp is of great significance to osteology, dentistry, and the development of artificial bone and other biomaterials. In this work, HAp nanoparticles were synthesized with the wet chemical precipitation method and their structure and morphologies were controlled by varying pH and adding fluoride ions by two different routes: (1) fluoride ions were added during synthesis, and (2) fluoride ions were introduced after the samples were synthesized by soaking the samples in solutions with fluoride ions. XRD and HRTEM were employed to confirm the composition and structure, while various multinuclear (1H, 19F, 31P) solid-state nuclear magnetic resonance (NMR) methods including 1D single pulse, cross-polarization under magic-angle spinning (CPMAS), and 2D heteronuclear correlation (HETCOR) were used to characterize the structure, morphology, and dynamics, validating the general core-shell morphology in these F-HAp samples. It was found that all hydroxide ions were substituted when the fluoride ion concentration was above 0.005 M. An NMR peak corresponding to water structure emerged and the bulk water peak was shifted upfield, indicating that fluoride substitution modifies both the crystalline core and the amorphous shell of F-HAp nanoparticles. With the second route of fluoride substitution, increases in soaking time or fluoride ion concentration could increase fluoride substitution in HAp, but could not achieve complete substitution. Finally, with 1H-31P CPMAS and HETCOR, it was established that there are two types of phosphorous, one in the crystalline core (PO43−) and the other in the amorphous shell (HPO42-). These results are valuable for clarifying the fluoride substitution mechanism in HAp in biomaterials or in organisms, and provide insights for developing next generation replacement materials for bone, tooth, or coating films, drug delivery systems, etc.

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“…The results also show that the Ca, O and P contents increased by increasing the bioglass content. This may be attributed to the presence of bioglass acting as a nucleating agent for the precipitation of apatite crystals on the scaffold’s surface [ 79 ]. Moreover, Figure 14 shows that the pore size gradient also induced a cell density gradient, with more cells found in the outer regions (large pores, better permeability) and a lower number of cells in the inner regions.…”

Section: Resultsmentioning

confidence: 99%

Novel 3D Bioglass Scaffolds for Bone Tissue Regeneration

et al. 2022

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The design of scaffolds with optimal biomechanical properties for load-bearing applications is an important topic of research. Most studies have addressed this problem by focusing on the material composition and not on the coupled effect between the material composition and the scaffold architecture. Polymer–bioglass scaffolds have been investigated due to the excellent bioactivity properties of bioglass, which release ions that activate osteogenesis. However, material preparation methods usually require the use of organic solvents that induce surface modifications on the bioglass particles, compromising the adhesion with the polymeric material thus compromising mechanical properties. In this paper, we used a simple melt blending approach to produce polycaprolactone/bioglass pellets to construct scaffolds with pore size gradient. The results show that the addition of bioglass particles improved the mechanical properties of the scaffolds and, due to the selected architecture, all scaffolds presented mechanical properties in the cortical bone region. Moreover, the addition of bioglass indicated a positive long-term effect on the biological performance of the scaffolds. The pore size gradient also induced a cell spreading gradient.

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Structure and formation of amorphous calcium phosphate and its role as surface layer of nanocrystalline apatite: Implications for bone mineralization

Cited by 57 publications

References 390 publications

Probing the Structure, Cytocompatibility, and Antimicrobial Efficacy of Silver-, Strontium-, and Zinc-Doped Monetite

Probing the Structure, Cytocompatibility, and Antimicrobial Efficacy of Silver-, Strontium-, and Zinc-Doped Monetite

Varying Synthesis Conditions and Comprehensive Characterization of Fluorine-Doped Hydroxyapatite Nanocrystals in a Simulated Body Fluid

Novel 3D Bioglass Scaffolds for Bone Tissue Regeneration

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