Zinc-Containing Calcium Phosphate Ceramics with a (Ca+Zn)/P Molar Ratio of 1.67

Abstract

Zinc-containing calcium phosphate ceramics with a (Ca+Zn)/P molar ratio of 1.67 (ZnHAP ceramics) were synthesized to clarify the main phase for zinc release. ZnHAP ceramics with a zinc content at or more than 0.20 wt% contained zinc-containing tricalcium phosphate. The ion activity product of monophasic ZnHAP ceramic containing at or less than 0.13 wt% of zinc corresponded to that of pure HAP ceramic. The presence of tricalcium phosphate (TCP) phases was necessary condition for ZnHAP ceramics to release zinc. The coexistence of TCP phases in the ZnHAP ceramics meant that a phase with a (Ca+Zn)/P molar ratio higher than 1.67 also coexisted. Although the phase was assumed to be zinc oxide, zinc was not concentrated anywhere in the ZnHAP ceramics including grain boundaries.

Unexpected Mechanism of Zn2+ Insertion in Calcium Phosphate Bioceramics

“…52 Then an estimated error of 1 wt % can be considered here for each phase proportion. The already described Znstabilizing feature for β-TCP, 19,39,43,60 at the expense of HAp, is clearly demonstrated by the series of the single Zn-substituted samples (Zn x -BCP samples with x = 0.00, 0.25, 0.50, 1.00, 1.50 and 2.00), as illustrated by dotted lines in Figure 2. The undoped BCP sample is mainly composed of HAp (93 wt % HAp, and 7 wt % β-TCP).…”

“…This (CaþZn)/P ratio has been frequently reported in the literature, and is at the origin of the reported inhibiting effect of zinc on HAp crystallization and the preference of Zn for β-TCP. 19,40,43,44,60 In spite of their nearly equal ionic radii, small Mg 2þ and Zn 2þ cations present different behavior with respect to HAp. Mg 2þ has an inhibiting effect on the crystallization of HAp because its substitution for calcium is extremely limited, and its presence favors the formation of β-TCP; this contrasts with Zn 2þ , which enters the HAp structure without substituting for calcium.…”

Evolution of magnetic and bone mineral phases in heat‐treated bioactive glass containing zinc and iron oxides

“…Earlier reports have also ruled out the possibility of Fe and Zn incorporation in the HA layer during immersion in SBF in agreement with our GI‐XRD results shown in Figure . Moreover, Sogo et al . have pointed out that it is difficult to form Zn containing apatite during immersion in SBF which might be the reason for its absence in our EDS data.…”

“…Zn 2+ migration enhances this negative charge which strengthens the electrostatic interaction with positively charged Ca ions in the SBF. Zn 2+ migrates into SBF solution and precipitates as zinc hydroxide (Zn(OH) 2 ) . In the case of glass heat treated at 750°C, a slower pH variation is observed as it has relatively lesser amount of ZnFe 2 O 4 phase (due to conversion into Fe 3 O 4 and α‐Fe 2 O 3 phases with increasing t A ).…”

Ostrich eggshell as calcium source for the synthesis of hydroxyapatite and hydroxyapatite partially substituted with zinc

“…Kawamura et al [12] showed the important influence of ZnTCP/HA in bone formation in critical defects created in femur of rabbits, with a 51% increase in new bone formation after implantation of a content of a ZnTCP/HA graft with 0.316% by weight of zinc, compared to TCP/ HA without zinc. Sogo et al [13] reported an increase in osteoblast proliferation with ZnHA when compared to HA in vitro assays.…”