Three-Dimensional Printing of a Hybrid Bioceramic and Biopolymer Porous Scaffold for Promoting Bone Regeneration Potential

Abstract

In this study, we proposed a three-dimensional (3D) printed porous (termed as 3DPP) scaffold composed of bioceramic (beta-tricalcium phosphate (β-TCP)) and thermoreversible biopolymer (pluronic F-127 (PF127)) that may provide bone tissue ingrowth and loading support for bone defect treatment. The investigated scaffolds were printed in three different ranges of pore sizes for comparison (3DPP-1: 150−200 μm, 3DPP-2: 250−300 μm, and 3DPP-3: 300−350 μm). The material properties and biocompatibility of the 3DPP scaffolds were characterized using scanning electron microscopy, X-ray diffractometry, contact angle goniometry, compression testing, and cell viability assay. In addition, micro-computed tomography was applied to investigate bone regeneration behavior of the 3DPP scaffolds in the mini-pig model. Analytical results showed that the 3DPP scaffolds exhibited well-defined porosity, excellent microstructural interconnectivity, and acceptable wettability (θ < 90°). Among all groups, the 3DPP-1 possessed a significantly highest compressive force 273 ± 20.8 Kgf (* p < 0.05). In vitro experiment results also revealed good cell viability and cell attachment behavior in all 3DPP scaffolds. Furthermore, the 3DPP-3 scaffold showed a significantly higher percentage of bone formation volume than the 3DPP-1 scaffold at week 8 (* p < 0.05) and week 12 (* p < 0.05). Hence, the 3DPP scaffold composed of β-TCP and F-127 is a promising candidate to promote bone tissue ingrowth into the porous scaffold with decent biocompatibility. This scaffold particularly fabricated with a pore size of around 350 μm (i.e., 3DPP-3 scaffold) can provide proper loading support and promote bone regeneration in bone defects when applied in dental and orthopedic fields.

Keywords: 3D printing; biocompatibility; bone regeneration; pluronic F127; tricalcium phosphate.

Figure 1

FE-SEM micrographs of (a) the synthesized β-TCP particles and (b) a higher magnification image taken from the white circle area in (a).

Figure 2

Morphology and chemical compositions of the investigated scaffolds: (a) 3DPP-1, (b) 3DPP-2, (c) 3DPP-3, and (d) an EDS spectrum taken from the surface of the printed 3DPP-1 scaffold. The FE-SEM observation and EDS analysis confirmed the presence of β-TCP particles (as pointed by arrows) in the printed lines.

Figure 3

XRD pattern taken from the investigated 3DPP-1 scaffold.

Figure 4

Wettability of the investigated 3DPP scaffolds. The surface is considered hydrophilic when the contact angle is smaller than 90°. No statistically significant difference (n = 5) in the hydrophilic contact angle found between all samples tested.

Figure 5

Compression testing results (n = 3) of the investigated 3DPP scaffolds: (a) 3DPP-1, (b) 3DPP-2, and (c) 3DPP-3. The 3DPP-1 scaffold exhibited the significantly highest compressive force as compared with 3DPP-2 and 3DPP-3 scaffolds (* p < 0.05).

Figure 6

(a) Cell viability of MG-63 of the investigated 3DPP scaffolds for 24 h. According to ISO 10993-5 specification, the tested material is considered an acute cytotoxic potential (a short-term culturing experiment (24 h)) if viability value of the tested material is less than 70% of the medium only control (100%). No statistically significant difference (n = 5) between tested samples. (b) cell morphologies of the investigated 3DPP scaffolds after culturing with MG-63 cells for 3 days. The higher magnification image was taken from the scaffold marked as black circular area. The filopodia (as pointed by arrows) of cells not only adhered flat, but also tightly grabbed the surface structure.

Figure 7

(a) Micro-CT images of the 3DPP scaffolds in the lateral condyle of mini-pig after implantation for 4 weeks, 8 weeks, and 12 weeks. Red arrows point the implanted scaffolds; green areas indicate the scanned bone tissues and (b) BV in the implanted areas evaluated through micro-CT at week 4, 8, and 12 after implantation. The 3DPP-3 scaffold exhibited significantly difference (n = 3) with 3DGP-1 scaffold at week 8 and week 12 (* p < 0.05).