Crystallized nano-sized alpha-tricalcium phosphate from amorphous calcium phosphate: microstructure, cementation and cell response

Abstract

New insight on the conversion of amorphous calcium phosphate (ACP) to nano-sized alpha tricalcium phosphate (α-TCP) provides a faster pathway to calcium phosphate bone cements. In this work, synthesized ACP powders were treated with either water or ethanol, dried, crystallized between 700 and 800 °C, and then cooled at different cooling rates. Particle size was measured in a scanning electron microscope, but crystallite size calculated by Rietveld analysis. Phase composition and bonding in the crystallized powder was assessed by x-ray diffraction and Fourier-transform infrared spectroscopy. Results showed that 50 nm sized α-TCP formed after crystallization of lyophilized powders. Water treated ACP retained an unstable state that may allow ordering to nanoapatite, and further transition to β-TCP after crystallization and subsequent decomposition. Powders treated with ethanol, favoured the formation of pure α-TCP. Faster cooling limited the growth of β-TCP. Both the initial contact with water and the cooling rate after crystallization dictated β-TCP formation. Nano-sized α-TCP reacted faster with water to an apatite bone cement than conventionally prepared α-TCP. Water treated and freeze-dried powders showed faster apatite cement formation compared to ethanol treated powders. Good biocompatibility was found in pure α-TCP nanoparticles made from ethanol treatment and with a larger crystallite size. This is the first report of pure α-TCP nanoparticles with a reactivity that has not required additional milling to cause cementation.

Mineral deposition promoted by resin-based sealants with different calcium phosphate additions

“…Nano-sized HAp has already been synthesized using different methods, 39,40 whereas little information can be found on the subject of nanometric OCP and α-TCP. 41 The nanometric size of HAp increased the surface area of the particle, thereby increasing the area for calcium phosphate nucleation on the surface of the samples, according to the outcome observed by mineral deposition analysis.…”

Niobium‐containing bioactive glasses modulate alkaline phosphatase activity during bone repair

“…18 While changes in blood levels are observed in Figure 2, direct comparisons with other studies are not possible as serum ALP is not commonly quantified in the assessment of new bone formation. While the effect of biomaterials on the local levels of ALP is described, 19,20 changes in serum ALP levels are also found in bone injury and modifications in tissue metabolism. [21][22][23][24] Modifications in ALP bone levels are expected as they are reduced after tissue injuries.…”

Calcium-phosphate ceramics in spine surgery: features of regeneration and use

“…Крім того, остеоіндуктивність КФК пов'язана з вивільненням іонів кальцію і фосфатів, які формують на поверхні імплантатів апатитний шар, який сорбує біологічно активні речовини, що сприяє хемотаксису мезенхімальних стовбурових клітин і впливає на їх здатність диференціюватися в остеобласти [14,15]. Розглядають також інші джерела клітинного походження, наприклад перицити чи ендотеліальні клітини, які активуються при взаємодії з факторами росту, що секретують місцеві запальні клітини [16].…”