Page 293 - IJB-10-6

International Journal of Bioprinting 3D-Printed Zn/MgHA-PCL for angio/osteogenesis

1,2,3,4,5,6-Cyclohexanehexacarboxylic acid monohydrate of the doping element in the samples was determined
(H L; C H O ·H O; molecular weight [M ] = 366.24, AR) by inductively coupled plasma atomic emission spectra
W
2
12
12
12
6
was purchased from TCI (Shanghai) Development Co., (ICP-AES; Avio 500; PerkinElmer, Singapore). The actual
Ltd. (China). Dichloromethane (M = 84.93) was provided doping efficiency, theoretical doping efficiency, and relative
W
by Zhiyuan Chemical Reagent Co., Ltd. (China). PCL doping efficiency of the element were calculated according
(M = 45,000) was purchased from Macklin Biochemical to Equations I–VI, as follows:
W
Technology Co., Ltd. (China). All reagents were used Actual doping of Zn (X a–Zn)
without further purification unless specifically mentioned.
2.2. Fabrication and evaluation of element-doped = × 100% (I)
hydroxyapatite and composite scaffolds
2.2.1. Synthesis of hydroxyapatite and Actual doping of Mg (X a–Mg)
element-doped hydroxyapatite
Several HA powders in this study were prepared by = × 100% (II)
hydrothermal methods, as previously reported. Briefly,
36
to prepare Zn-doped HA with designed Zn/(Zn + Ca)
molar ratios of 10% (denoted as 10Zn@HA), Ca(NO ) , Theoretical doping of Zn (X t–Zn)
3 2
Zn(NO ) , and Na HPO were sequentially added into 150
2
3 2
4
mL of deionized water, while the molar ratio of (Ca + Zn)/P =
in the solution was 1.67. To prepare Zn/Mg-doped HA with
a designed molar ratio of 10% Zn/(Zn + Mg + Ca) with × 100% (III)
5%/10%/15% Mg/(Zn + Mg + Ca) (denoted as 5Mg10Zn@
HA, 10Mg10Zn@HA, and 15Mg10Zn@HA, respectively), Theoretical doping of Mg (X t–Mg)
Ca(NO ) , Zn(NO ) , Mg(NO ) , and Na HPO were
3 3
3 2
4
2
3 2
sequentially added into 150 mL of deionized water, while =
the molar ratio of (Ca + Zn + Mg)/P in the solution was
1.67. The prepared solutions were all magnetically stirred, × 100% (IV)
and the Ca was determined as 0.1 M. Then, the pH of
2+
the mixture was adjusted to 2.3 with HNO (10.83 M),
3
followed by the addition of H L (1 mM). After the H L was Relative doping of Zn (R ) = × 100% (V)
Zn
6
6
dissolved completely, urea (0.56 M) was added until it was
completely dissolved. The prepared solutions were then
transferred to six-station Teflon autoclaves (Xataikang,
China) for reaction at 200°C for 12 h. The precipitates were Relative doping of Mg (R ) = × 100% (VI)
Mg
collected after the reactions were completed. The obtained
precipitates were rinsed by centrifugation at 4000 rpm for
3 min, followed by repeated cleaning with deionized water where n(Ca) actual , n(Zn) actual , and n(Mg) actual represent
and absolute ethanol until the pH value reached neutral; the actual contents of Ca, Zn, and Mg in the element-
the precipitates were then dried in an oven at 65°C for 48 h. doped HA, respectively; n(Ca) theoretical , n(Zn) theoretical , and
The un-doped HA was fabricated using the same method. n(Mg) theoretical represent the theoretical contents of Ca, Zn,
and Mg in the element-doped HA, respectively.
2.2.2. Characterization of
element-doped hydroxyapatite 2.2.3. Preparation of 3D-printed composite scaffolds
The morphology, elements, and phase compositions Several porous 3D composite scaffolds were fabricated by
37
of the samples were examined using scanning electron 3D printing (Biobulid-S, China) as reported previously.
microscopy (SEM; VEGA3; TESCAN, Czech Republic) Before printing, 0.5 g of HA, 10Zn@HA, 5Mg10Zn@HA,
equipped with energy dispersive X-ray spectroscopy (EDS) 10Mg10Zn@HA, and 15Mg10Zn@HA powders were
and X-ray diffraction (XRD; D8 ADVANCE Da Vinci, dispersed in 40 mL of dichloromethane and stirred to form
Cu, 40 mA, 40 kV; Bruker, Germany), respectively. The uniform dispersion, respectively. Then, the dispersion
chemical structure was examined using Fourier transform was added into a PCL solution (4.5 g of PCL in a certain
infrared spectroscopy (FTIR, 500–3500 cm , Thermo amount of dichloromethane) and fully stirred for 3 h to
−1
Nicolet 6700; Thermo Fisher Scientific, USA). The quantity form a uniform ink. The printing procedure is illustrated in

Volume 10 Issue 6 (2024) 285 doi: 10.36922/ijb.4243