Effect of pH level and calcination on the production of calcium phosphates by acidic route of wet precipitation

Abstract

Multiphasic calcium phosphate powders were synthesized by the acidic route, using lactic acid as a chelating agent that allows the production of a stable and rich solution of calcium and phosphate ions at room temperature. After pH adjusting, without varying the concentrations of precursor solution, XRD and FTIR analyses showed different CaP phases before and after heat treatment at 1000 °C. At pH 5, brushite plate-like particles were produced, while at higher pH levels (7 to 12) nano-hydroxyapatite particles were formed. After the calcination process, partial and total decomposition of hydroxyapatite in the β-TCP phase was explained by XRF analysis due to the calcium-deficient hydroxyapatite of synthesized samples at pH 7 and 10. This work presents an important method to synthesize any desired CaP phase compositions by varying the pH level and subsequently performing heat treatment, which has a direct effect on morphology, crystallinity, and formation of different CaP powders.

Chitosan/Xanthan/Hydroxyapatite-graphene oxide porous scaffold associated with mesenchymal stem cells for dentin-pulp complex regeneration

“…In Figure 2(b), the diffraction bands of HA single phase (JCPDS 09-0432) can be seen in CXHA, CXHAGO 0.5wt%, CXHAGO 1.0wt% and CXHAGO 1.5wt% scaffolds. 37 It is possible to observe that HA maintained its crystallinity characteristics after the scaffold synthesis with the CX and GO at different concentrations. The GO particles also show their characteristic peak in the XRD spectrum, at 2θ = 11° on the graph.…”

“…Chitosan-Xanthan Scaffolds synthesis was adapted from the protocol described by Neves et al 36 The solutions used were 1% Xanthan (m/v) in deionized water (Melli-Q system, Millipore) (pH = 7.7) and Chitosan at 1% (w/v) in an acetic acid at 1% (v/v) aqueous solution. The HA particles used were derived from the calcium phosphate synthesis, following the method described by Neves et al 37 HA-GO particles were obtained following the protocol described by Lopes et al 34 These particles were incorporated into this formulation at the 5wt% by a bioreactor BIO-TEC-PRO (Tecnal, São Paulo, Brazil) and kept under stirring at 1000 r/min with the aid of a Q-251 D mechanical stirrer (Quimis). The solution was divided equally in mass terms in polystyrene Petri dishes with 15 cm in diameter and with air circulation (model 410D, Nova Ethics) at a 37.0°C for approximately 48 h. After that, the plates were frozen for 24 h at À27°C and freeze-dried in a freeze-dryer Alpha 1-2 LDplus equipment (Christ, Osterode am Harz, Germany) for 48 h, using synthesis process can be seen in Figure 1.…”

Cellulose acetate scaffold containing hydroxyapatite/graphene oxide nanocomposite by electrospinning for advanced regenerative therapies

“…Consequently, crystallinity emerges as a critical determinant in evaluating and enhancing the overall effectiveness of advanced cell therapies. 11,16…”

“…The HA solution was obtained from the synthesis of calcium phosphate through the acidic route of wet precipitation, as described in our previous studies. 16 The HAGO solution was obtained using the protocol described by Lopes et al, 17 which was previously published.…”

Cell-Friendly Chitosan-Xanthan Gum Membranes Incorporating Hydroxyapatite Designed for Periodontal Tissue Regeneration

“…The diffractograms for the C 1 X 1 HA 10 formulation and HA powder itself (obtained by the International Center for Diffraction Data 00-009-0432, [ 31 ]) confirm that a product with low to medium crystallinity and similar to the mineral phase of human bone was obtained. The characteristic peaks of the crystalline structural plane of the HA phase, comprising the eight main peaks of angular position between 25° and 50°, were observed [ 32 ]. These results suggest that the HA powder incorporation into the C-X polyelectrolyte complex does not change the HA crystallinity and phase characteristics, despite the use of acetic acid for chitosan dissolution [ 29 ].…”