Limits...
Hydrogen-substituted β -tricalcium phosphate synthesized in organic media

View Article: PubMed Central - HTML - PubMed

ABSTRACT

β-Tricalcium phosphate (β-TCP) platelets synthesized in ethylene glycol offer interesting geometries for nano-structured composite bone substitutes but were never crystallographically analyzed. In this study, powder X-ray diffraction and Rietveld refinement revealed a discrepancy between the platelet structure and the known β-TCP crystal model. In contrast, a model featuring partial H for Ca substitution and the inversion of P1O4 tetrahedra, adopted from the whitlockite structure, allowed for a refinement with minimal misfits and was corroborated by HPO42− absorptions in Fourier-transform IR spectra. The Ca/P ratio converged to 1.443 ± 0.003 (n = 36), independently of synthesis conditions. As a quantitative verification, the platelets were thermally decomposed into hydrogen-free β-TCP and β-calcium pyrophosphate which resulted in a global Ca/P ratio in close agreement with the initial β-TCP Ca/P ratio (ΔCa/P = 0.003) and with the chemical composition measured by inductively coupled plasma (ΔCa/P = 0.003). These findings thus describe for the first time a hydrogen-substituted β-TCP structure, i.e. a Mg-free whitlockite, represented by the formula Ca21 − x(HPO4)2x(PO4)14 − 2x, where x = 0.80 ± 0.04, and may have implications for resorption properties of bone regenerative materials.

No MeSH data available.


Related in: MedlinePlus

Transmission FTIR spectra of sintered β-TCP and β-TCP platelets. The phosphate absorption regions show several differences in relative peak intensity and/or peak shifts between the two materials. Platelets but not sintered β-TCP exhibited an absorption band at 875 cm−1, attributable to HPO42− groups.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5134762&req=5

fig2: Transmission FTIR spectra of sintered β-TCP and β-TCP platelets. The phosphate absorption regions show several differences in relative peak intensity and/or peak shifts between the two materials. Platelets but not sintered β-TCP exhibited an absorption band at 875 cm−1, attributable to HPO42− groups.

Mentions: The phosphate absorption region in the FTIR spectra of sintered β-TCP as well as β-TCP platelets is shown in Fig. 2 ▸. (The full wavenumber range is presented in the supporting information §S2.2; Fig. S2). The absorption bands observed in sintered β-TCP are consistent with previous reports (Jillavenkatesa & Condrate, 1998 ▸; Berzina-Cimdina & Borodajenko, 2012 ▸; Bigi et al., 1997 ▸). Specifically, the bands at approximately 1120, 1105, 1080, 1042 and 1025 cm−1 can be assigned to the ν3 vibrational mode of the PO43− ion. Moreover, ν1-PO4 bands were observed at 970 and 942 cm−1, ν4-PO4 bands at 605, 592, 545 and 552 cm−1 and two weak ν2-PO4 bands at 415 and 435 cm−1. Additional weak absorptions, e.g. at 572 cm−1, also agree with previously reported β-TCP spectra (Bigi et al., 1997 ▸).


Hydrogen-substituted β -tricalcium phosphate synthesized in organic media
Transmission FTIR spectra of sintered β-TCP and β-TCP platelets. The phosphate absorption regions show several differences in relative peak intensity and/or peak shifts between the two materials. Platelets but not sintered β-TCP exhibited an absorption band at 875 cm−1, attributable to HPO42− groups.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5134762&req=5

fig2: Transmission FTIR spectra of sintered β-TCP and β-TCP platelets. The phosphate absorption regions show several differences in relative peak intensity and/or peak shifts between the two materials. Platelets but not sintered β-TCP exhibited an absorption band at 875 cm−1, attributable to HPO42− groups.
Mentions: The phosphate absorption region in the FTIR spectra of sintered β-TCP as well as β-TCP platelets is shown in Fig. 2 ▸. (The full wavenumber range is presented in the supporting information §S2.2; Fig. S2). The absorption bands observed in sintered β-TCP are consistent with previous reports (Jillavenkatesa & Condrate, 1998 ▸; Berzina-Cimdina & Borodajenko, 2012 ▸; Bigi et al., 1997 ▸). Specifically, the bands at approximately 1120, 1105, 1080, 1042 and 1025 cm−1 can be assigned to the ν3 vibrational mode of the PO43− ion. Moreover, ν1-PO4 bands were observed at 970 and 942 cm−1, ν4-PO4 bands at 605, 592, 545 and 552 cm−1 and two weak ν2-PO4 bands at 415 and 435 cm−1. Additional weak absorptions, e.g. at 572 cm−1, also agree with previously reported β-TCP spectra (Bigi et al., 1997 ▸).

View Article: PubMed Central - HTML - PubMed

ABSTRACT

β-Tricalcium phosphate (β-TCP) platelets synthesized in ethylene glycol offer interesting geometries for nano-structured composite bone substitutes but were never crystallographically analyzed. In this study, powder X-ray diffraction and Rietveld refinement revealed a discrepancy between the platelet structure and the known β-TCP crystal model. In contrast, a model featuring partial H for Ca substitution and the inversion of P1O4 tetrahedra, adopted from the whitlockite structure, allowed for a refinement with minimal misfits and was corroborated by HPO42− absorptions in Fourier-transform IR spectra. The Ca/P ratio converged to 1.443 ± 0.003 (n = 36), independently of synthesis conditions. As a quantitative verification, the platelets were thermally decomposed into hydrogen-free β-TCP and β-calcium pyrophosphate which resulted in a global Ca/P ratio in close agreement with the initial β-TCP Ca/P ratio (ΔCa/P = 0.003) and with the chemical composition measured by inductively coupled plasma (ΔCa/P = 0.003). These findings thus describe for the first time a hydrogen-substituted β-TCP structure, i.e. a Mg-free whitlockite, represented by the formula Ca21 − x(HPO4)2x(PO4)14 − 2x, where x = 0.80 ± 0.04, and may have implications for resorption properties of bone regenerative materials.

No MeSH data available.


Related in: MedlinePlus