Gypsum transformation to calcium phosphates

Goldberg, M. A.; Фомин, А. С.; Petrakova, N. V.; Fedotov, A. Yu.; Shvorneva, L. I.; Смірнов, В. В.; Popova, A. V.; Баринов, С. М.

doi:10.1134/s0012500812050035

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“…Similarly, the addition of CSH to HAP cement showed a marked improvement in in vivo properties, such as good biocompatibility after implantation in rat muscle and a gradual bioresorption over 12 weeks with blood vessels penetrating the material [ 17 ]. On the other hand, the ability of CSH to achieve rapid transformation in 0.1 M (NH 4 ) 2 HPO 4 solution to amorphous calcium phosphate and dicalcium phosphate with a composition close to tricalcium phosphate has been verified [ 18 ], and this result is in accordance with the results of in vivo experiments. In the case of setting time, small variations in setting time (ST) of fast setting αTCP cement with a change of H 2 SO 4 concentration (up to 0.33 M) in a liquid component have been revealed [ 19 ], contrary to the strong effect of the liquid/powder (L/P) ratio found in CPC/CSH cement pastes, which clearly indicates the need to optimize this parameter [ 20 ].…”

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confidence: 67%

Tetracalcium Phosphate/Monetite/Calcium Sulfate Hemihdrate Biocement Powder Mixtures Prepared by the One-Step Synthesis for Preparation of Nanocrystalline Hydroxyapatite Biocement-Properties and In Vitro Evaluation

et al. 2021

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A modified one-step process was used to prepare tetracalcium phosphate/monetite/calcium sulfate hemihydrate powder cement mixtures (CAS). The procedure allowed the formation of monetite and calcium sulfate hemihydrate (CSH) in the form of nanoparticles. It was hypothesized that the presence of nanoCSH in small amounts enhances the in vitro bioactivity of CAS cement in relation to osteogenic gene markers in mesenchymal stem cells (MSCs). The CAS powder mixtures with 15 and 5 wt.% CSH were prepared by milling powder tetracalcium phosphate in an ethanolic solution of both orthophosphoric and sulfuric acids. The CAS cements had short setting times (around 5 min). The fast setting of the cement samples after the addition of the liquid component (water solution of NaH2PO4) was due to the partial formation of calcium sulfate dihydrate and hydroxyapatite before soaking in SBF with a small change in the original phase composition in cement powder samples after milling. Nanocrystalline hydroxyapatite biocement was produced by soaking of cement samples after setting in simulated body fluid (SBF). The fast release of calcium ions from CAS5 cement, as well as a small rise in the pH of SBF during soaking, were demonstrated. After soaking in SBF for 7 days, the final product of the cement transformation was nanocrystalline hydroxyapatite. The compressive strength of the cement samples (up to 30 MPa) after soaking in simulated body fluid (SBF) was comparable to that of bone. Real time polymerase chain reaction (RT-PCR) analysis revealed statistically significant higher gene expressions of alkaline phosphatase (ALP), osteonectin (ON) and osteopontin (OP) in cells cultured for 14 days in CAS5 extract compared to CSH-free cement. The addition of a small amount of nanoCSH (5 wt.%) to the tetracalcium phosphate (TTCP)/monetite cement mixture significantly promoted the over expression of osteogenic markers in MSCs. The prepared CAS powder mixture with its enhanced bioactivity can be used for bone defect treatment and has good potential for bone healing.

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