Enhancement of the Pore Interconnectivity and Porosity of Calcium Phosphate Scaffolds by Acid-Etching Method

doi:10.1007/s40195-015-0301-1

Abstract

Abstract:

Porous hydroxyapatite (HA)-tricalcium phosphate (TCP) ceramic scaffolds were prepared using a screw-type extrusion method with polymer beads. HA and dicalcium phosphate dehydrates (DCPD) were added at various ratios to obtain different HA/TCP ratios in sintered ceramic scaffolds. To further enhance the pore interconnectivity and porosity, the developed porous ceramic scaffolds were etched with acid solutions. The maximum porosity (~85%) was observed in the Ca-P scaffold with the lowest HA (~7%) content. On the other hand, the maximum compressive strength was noted in the scaffolds with the highest HA content (~85%). X-ray diffraction showed that the extent of the β-TCP to α-TCP phase transformation increased with decreasing HA/DCPD ratio. All HCl-etched scaffolds were observed to generate micropores, which improved the interconnectivity, while biomineralization was found to be the same for both the HCl-etched and non-etched scaffolds. In particular, hydrochloric acid etching is a promising method for improving the interconnectivity and porosity of the ceramic scaffolds.

Key words: Screw-type extrusion, Biomineralization, Porous ceramic scaffolds, HCl etching, Interconnectivity

Sujeong Lee, Soyoung Yang, Indu Bajpai, Inn-Kyu Kang, Sukyoung Kim. Enhancement of the Pore Interconnectivity and Porosity of Calcium Phosphate Scaffolds by Acid-Etching Method[J]. Acta Metallurgica Sinica (English Letters), 2015, 28(9): 1109-1116.

Figures/Tables 9

Table 1 Sample’s nomenclature and composition of raw materials and additives

Sample	HA/DCPD ratio	HA (g)	DCPD (g)	Ca(OH)₂ (g)	PMMA	H₂O	Binder
H0D100	0:1	0	100	30.07	70 vol%	72 vol%	22 wt%
H50D100	1:2	50	100	30.07
H100D100	1:1	100	100	30.07
H100D50	2:1	200	100	30.07

Fig. 1 SEM images of PMMA beads.

Fig. 2 SEM images of sintered porous blocks: a H0D100; b H50D100; c H100D100; d H100D50.

Fig. 3 HA and TCP phase quantification by XRD.

Fig. 4 Compressive strength and porosity of the porous scaffolds.

Fig. 5 SEM images of HCl-treated H100D100 porous blocks with various concentrations and durations.

Fig. 6 Comparison of the porosity change of HCl-etched porous blocks with various concentrations and time: a 1 min, b 2 min, c 3 min, d 4 min.

Fig. 7 Comparison of the weight change of the HCl-etched porous blocks with various concentrations and duration: a 1 min, b 2 min, c 3 min, d 4 min.

Fig. 8 SEM images of 7-days biomineralization of non-etched a-d and HCl-etched a*-d* scaffolds: a H0D100; b H50D100; c H100D100; d H100D50.

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