A novel method for monitoring mineralisation in hydrogels at the engineered hard–soft tissue interface

Koburger, Susanne; Bannerman, Alistair; Grover, Liam M.; Müller, Frank A.; Bowen, James; Paxton, Jennifer Z.

doi:10.1039/c3bm60102a

Cited by 18 publications

(20 citation statements)

References 48 publications

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“…Ageing of brushite cements in-vivo 45671826 and in-vitro 16232728 has been undertaken by a number of groups with inconsistent results. For in-vitro ageing a range of ageing mediums including distilled water29, simulated body fluid (SBF)23, PBS162327, cell culture medium1730, and bovine serum16 have been used. In these studies brushite has been shown to undergo dissolution and transformation to OCP, as reported here, or hydroxyapatite depending on the cement composition and conditions it has been aged in.…”

Section: Discussionmentioning

confidence: 99%

Visualising phase change in a brushite-based calcium phosphate ceramic

Bannerman

Williams

Cox

et al. 2016

Sci Rep

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The resorption of brushite-based bone cements has been shown to be highly unpredictable, with strong dependence on a number of conditions. One of the major factors is phase transformation, with change to more stable phases such as hydroxyapatite affecting the rate of resorption. Despite its importance, the analysis of phase transformation has been largely undertaken using methods that only detect crystalline composition and give no information on the spatial distribution of the phases. In this study confocal Raman microscopy was used to map cross-sections of brushite cylinders aged in Phosphate Buffered Saline, Foetal Bovine Serum, Dulbecco’s – Minimum Essential Medium (with and without serum). Image maps showed the importance of ageing medium on the phase composition throughout the ceramic structure. When aged without serum, there was dissolution of the brushite phase concomitant to the deposition of octacalcium phosphate (OCP) around the periphery of the sample. The deposition of OCP was detectable within five days and reduced the rate of brushite dissolution from the material. The use of serum, even at a concentration of 10vol% prevented phase transformation. This paper demonstrates the value of confocal Raman microscopy in monitoring phase change in biocements; it also demonstrates the problems with assessing material degradation in non-serum containing media.

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Section: Discussionmentioning

confidence: 99%

Visualising phase change in a brushite-based calcium phosphate ceramic

Bannerman

Williams

Cox

et al. 2016

Sci Rep

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“…Brushite powder has been incorporated in an alginate matrix for fertilizer purposes and the recrystallisation of brushite in alginate at a cement-hydrogel interface has been studied by Ramanspectroscopy. 30,31 A recent attempt was made by Amer et al to precipitate brushite in situ with alginate. 32 While mineral was formed within the hydrogel, little attention was paid to reaction conditions or biocompatibility which resulted in poorly defined composites and unstable gels.…”

Section: Introductionmentioning

confidence: 99%

Controlled mineralisation and recrystallisation of brushite within alginate hydrogels

Bjørnøy¹,

Bassett²,

Ucar³

et al. 2016

Biomed. Mater.

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Abstract. Due to high solubility and resorption behaviour under physiological conditions, brushite (CaHPO 4 ·2H 2 O, calcium monohydrogen phosphate dihydrate, dicalcium phosphate dihydrate) has great potential in bone regeneration applications, both in combination with scaffolds or as component of calcium phosphate cements. The use of brushite in combination with hydrogels opens possibilities for new cell based tissue engineering applications of this promising material. However, published preparation methods of brushite composites, in which the mineral phase is precipitated within the hydrogel network, fail to offer the necessary degree of control over mineral phase, content and distribution within the hydrogel matrix. The main focus of this study was to address these shortcomings by determining precise fabrication parameters needed to prepare composites with controlled composition and properties. Composite alginate microbeads were prepared using a counter-diffusion technique which allows for simultaneous crosslinking of the hydrogel and precipitation of an inorganic mineral phase. Reliable nucleation of a desired mineral phase within the alginate network proved more challenging than simple aqueous precipitation. This was largely due to ion transport within the hydrogel producing concentration gradients that modified levels of supersaturation and favoured the nucleation of other phases such as hydroxyapatite and octacalcium phosphate which would otherwise not form. To overcome this, incorporation of brushite seed crystals resulted in good control over the mineral phase and by adjusting the amount of seeds and precursor concentration, the amount of mineral could be tuned. The material has been characterized with a range of physical techniques, including scanning electron microscopy, powder X-ray diffraction and Rietveld refinement, Fourier transform infrared spectroscopy and thermogravimetric analysis, in order to assess mineral morphology, phase and amount within the organic matrix. The mineral content of the composite material converted from brushite into hydroxyapatite when submerged in simulated body fluid, indicating possible bioactivity. Additionally, initial cell culture studies revealed that both the material and the synthesis procedure is compatible with cells relevant to bone tissue engineering.

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“…S1) are similar to those reported in other papers. [33][34][35][36][37][38][39] Main bands can be observed at roughly 880, 985, 1060, 1080, 1115 and 1132 cm À1 . However, some differences in intensities and wavenumbers can be observed between these spectra (also seen in the cited references), suggesting possible crystalline effects.…”

Section: Results and Discussion Introductionmentioning

confidence: 95%

Polarized Raman spectra of brushite (CaHPO₄.2H₂O) crystal. Investigation of the phosphate stretching modes, study of the LOTO splitting

Quillard

Mevellec

Deniard

et al. 2016

J Raman Spectroscopy

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Polarized Raman measurements were recorded on a monoclinic brushite (CaHPO 4 .2H 2 O) crystal in the 800-1200 cm À1 spectral range, corresponding to the P-O stretching modes. This study is a continuation of the investigation of the phosphate stretching modes observed in polarized infrared reflectance spectra of brushite crystal. In such ionic non-centrosymmetric crystals, the splitting between the transverse and longitudinal components of the optic vibrations was observed in the polarized Raman spectra recorded at several scattering geometries. A″ symmetry modes of the brushite crystal were measured. Using a simple model based on the symmetry of the PO 4 group, the Raman intensities of the stretching modes are calculated and compared with experimental bands. IntroductionDi(basic) calcium phosphate dihydrate (DCPD; CaHPO 4 .2H 2 O) is also known as the rare mineral 'brushite'. This mineral was discovered in 1865 by G. E. Moore [1] who called it 'brushite' in honor of Professor George Jarvis Brush an American mineralogist (Yale University, New Haven, Connecticut, USA). DCPD can be found [2][3][4] in pathological calcifications and some carious lesions. In bone surgery, DCPD is used as calcium phosphate cements, [5][6][7][8] and in dentistry, [9][10][11][12][13] it is added to toothpaste both for caries protection and as a polishing agent. In the dairy industry, DCPD is used as a mineral supplement as its importance as a constituent of infant's food was discovered [14] as early as 1917. In the food industry, it serves as a texturizer, bakery improver and water retention additive. [15] Other applications [16,17] have been reported including flame retardant, slow-release fertilizer, anticorrosive and passivating pigment for some ground coat paints.The crystalline structure of DCPD has been investigated by several groups. [18][19][20][21] This compound as well as other isostructural ones (gypsum and pharmacolite [22,23] ) is described by a noncentrosymmetric monoclinic space group Ia with, for brushite, the following cell parameters a = 5.812 Å; b = 15.180 Å; c = 6.239 Å; β = 116.25°and Z = 4. Large tabular thin-plate transparent crystals can be obtained.Among the vibrations of this compound, the P-O stretching modes are located in the 800-1200-cm À1 wavenumber range where no other bands are expected. In Raman scattering, as in infrared (IR) spectroscopy, these bands are very intense and well separated; moreover, the spectra exhibit a strong molecular character associated with the internal modes of PO 4 group. [24] Finally, in several calcium orthophosphate compounds, changes in the structure strongly affect these modes, for example, calcium substitution by other cations. [25][26][27] That is why, the study of these bands is especially interesting, and we focused our work on these modes.Four P-O stretching, vibrations are combined in the phosphate tetrahedron to give four modes, numbered [28] Q 1 to Q 4 in increasing wavenumber order (with the pseudo-symmetry [29] C 3v ). Considering the space group Ia and the presenc...

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A novel method for monitoring mineralisation in hydrogels at the engineered hard–soft tissue interface

Cited by 18 publications

References 48 publications

Visualising phase change in a brushite-based calcium phosphate ceramic

Visualising phase change in a brushite-based calcium phosphate ceramic

Controlled mineralisation and recrystallisation of brushite within alginate hydrogels

Polarized Raman spectra of brushite (CaHPO₄.2H₂O) crystal. Investigation of the phosphate stretching modes, study of the LOTO splitting

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A novel method for monitoring mineralisation in hydrogels at the engineered hard–soft tissue interface

Cited by 18 publications

References 48 publications

Visualising phase change in a brushite-based calcium phosphate ceramic

Visualising phase change in a brushite-based calcium phosphate ceramic

Controlled mineralisation and recrystallisation of brushite within alginate hydrogels

Polarized Raman spectra of brushite (CaHPO4.2H2O) crystal. Investigation of the phosphate stretching modes, study of the LOTO splitting

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Polarized Raman spectra of brushite (CaHPO₄.2H₂O) crystal. Investigation of the phosphate stretching modes, study of the LOTO splitting