SUPPORTING INFORMATION
Electrolytic one-pot synthesis of Group II nanohydroxyapatite
S1. Preparation of solutions
- Ca-EDTA-PO43- solution:
20 g of NaOH was dissolved in 550 mL DDW, and then 93.05 g of EDTA disodium salt was added. The mixture was stirred and heated gently until obtain a translucent solution. To this solution was added 36.75 g of CaCl2·2H2O dissolved in 100 mL of DDW and the pH adjusted to 7.5. Finally 23.83 g from K2HPO4 dissolved in 100 mL was added. The pH of the solution is adjusted with NaOH (1 + 1) to the working pH and volume adjusted to 1 L in a volumetric flask.
- Ca/Mg-EDTA-PO43- (Ca:Mg 4:1) solution:
10.96 g of EDTA acid was added to 50 mL DDW, then 5 mL NH3 (ac.) solution was added. The mixture was stirred and heated gently until obtain a translucent solution. To this solution was added 4.4 g of CaCl2·2H2O and 1.5 g of MgCl2·H2O dissolved in 50 mL of DDW, and the pH adjusted to 7.5 with NH3 (ac.). Finally 3.95 g from K2HPO4 dissolved in 30 mL was added. The pH of the solution is adjusted with NH3 (ac.) to pH 7.0 and volume adjusted to 150 mL in a volumetric flask.
- Ca/Mg-EDTA-PO43- (Ca:Mg 6:1) solution:
10.96 g of EDTA acid was added to 50 mL DDW, then 5 mL NH3 (ac.) solution was added. The mixture was stirred and heated gently until obtain a translucent solution. To this solution was added 5.1 g of CaCl2·2H2O and 0.51 g MgCl2·H2O dissolved in 50 ml of DDW, and the pH adjusted to 7.5 with NH3 (ac.). Finally 3.95 g from K2HPO4 dissolved in 30 mL was added. The pH of the solution is adjusted with NH3 (ac.) to pH 7.0 and volume adjusted to 150 mL in a volumetric flask.
- Sr-EDTA-PO43- solution:
10.96 g of EDTA acid was added to 50 mL DDW, then 5 mL NH3 (ac.) solution was added. The mixture was stirred and heated gently until obtain a translucent solution. To this solution was added 7.94 g of Sr(NO3)2 dissolved in 40 ml of DDW and the pH adjusted to 7.5 with NH3 (ac.). Finally 3.95 g from K2HPO4 dissolved in 30 mL was added. The pH of the solution is adjusted with NH3 (ac.) to 7.0 pH and volume adjusted to 150 mL in a volumetric flask.
- Ba-EDTA-PO43- solution:
10.96 g of EDTA acid was added to 50 mL distilled water, then 10 mL NH3 (ac.) solution was added. The mixture was stirred and heated gently until obtain a translucent solution. To this solution was added 9.16 g of BaCl2·2H2O dissolved in 50 ml of distilled water and the pH adjusted to 11.0 with NH3 (ac.). Finally 3.95 g from K2HPO4 dissolved in 30 mL was added. The pH of the solution is adjusted with NH3 (ac.) to pH 11.0 and volume adjusted to 250 mL in a volumetric flask.
S2. Electrolytic synthesis conditions.
The parameters studied are divided in two major groups: P-series (pH) and D-series (current density). It also shows the conditions for the synthesis of Sr-HA, Ba-HA, Mg-Ca-HA samples and yield in gram hours-1 (g h-1).
System / Sample / J(mA cm-2) / solution pH / Voltage Range
(V) / Apatite Yield
(g h-1)
[Ca-EDTA]2- / PO43-]
Ca/P = 1,67
pH variable / P01 / 144 / 4.01 / 5.65 – 7.10 / 0.59
P02 / 144 / 5.01 / 0.71
P03 / 144 / 5.88 / 0.51
P04 / 144 / 6.50 / 0.52
P05 / 144 / 7.03 / 0.57
P06 / 144 / 7.50 / 0.58
P07 / 144 / 8.04 / 0.60
P08 / 144 / 8.40 / 0.78
P09 / 144 / 8.52 / 0.71
P10 / 144 / 9.00 / 0.67
P11 / 144 / 9.60 / 0.75
P12 / 144 / 10.13 / 0.72
P13 / 144 / 11.01 / 0.77
P14 / 144 / 13.30 / 0.86
[Ca-EDTA]2- / PO43-]
Ca/P = 1,67
J(mA∙cm-2) variable / D01 / 60 / 7.00 / 4.40 – 4.75 / 0.30
D02 / 80 / 7.00 / 4.90 – 5.40 / 0.32
D03 / 100 / 7.00 / 6.65 – 7.00 / 0.50
D04 / 120 / 7.00 / 6.10 – 7.10 / 0.41
D05 / 137 / 7.00 / 6.35 – 7.00 / 0.53
D06 / 144 / 7.00 / 5.90 – 6.15 / 0.59
D07 / 160 / 7.00 / 6.82 – 6.89 / 0.82
D08 / 180 / 7.00 / 7.30 – 7.80 / 0.69
D09 / 210 / 7.00 / 7.82 – 7.47 / 0.71
D10 / 240 / 7.00 / 8.20 – 9.10 / 1.04
D11 / 260 / 7.00 / 8.30 – 8.80 / 1.16
[Sr-EDTA]2-/PO43-] / Sr-HA / 144 / 6.95 / 5.70 – 7.10 / 0.96
[Ba-EDTA]2-/PO43-] / Ba-HA / 144 / 11.00 / 6.50 – 7.50 / 1.22
[Mgx/Ca1-x-EDTA]2-/PO43-] / Ca-Mg-HA1 / 160 / 7.50 / 6.00 – 7.80 / 0.73
[Mgx/Ca1-x-EDTA]2-/PO43-] / Ca-Mg-HA2 / 160 / 7.06 / 6.00 – 7.80 / 0.64
S3.Calculated a and b cell parameters.
solution pH / a(Å) / c
(Å) / J
(mA cm-2) / a
(Å) / c
(Å)
4.0 / 9.433 / 6.891 / 60 / 9.455 / 6.888
5.0 / 9.453 / 6.879 / 80 / 9.449 / 6.884
5.9 / 9.450 / 6.884 / 100 / 9.450 / 6.884
6.5 / 9.440 / 6.890 / 120 / 9.450 / 6.886
7.0 / 9.440 / 6.886 / 137 / 9.444 / 6.883
7.5 / 9.440 / 6.883 / 144 / 9.440 / 6.886
8.0 / 9.434 / 6.899 / 160 / 9.444 / 6.894
8.4 / 9.432 / 6.894 / 180 / 9.429 / 6.893
8.5 / 9.416 / 6.899 / 210 / 9.428 / 6.902
9.0 / 9.430 / 6.894 / 240 / 9.396 / 6.905
9.6 / 9.425 / 6.896 / 260 / 9.391 / 6.912
10.1 / 9.439 / 6.891
11.0 / 9.413 / 6.900
13.3 / 9.401 / 6.901
Theoretical Parameter. P63/m / 9.42 / 6.88
S4. EDS analysis of some Ca-HA samples.
S5. XRD patterns for Ca-HA synthesized associated with pH variable (P01-P14). Arrows denotes change in resolution and peak broadening in the region of 2Ɵ=31-34º. It shows the relative intensity change corresponding to the crystallographic plane (002) and (004) signaled with lower pH solution.
S6. EDS analysis of the Ca-Mg-HA1 sample.