Abstract
3D-printed titanium (Ti) materials have attracted much attention in the field of bone tissue repair. However, the combination strength of traditional alloy materials with bone tissue is lower, and the elastic modulus is higher than that of natural bone tissue, which makes the titanium alloy susceptible to stress shielding phenomena after implantation. Therefore, it is urgent to find better surface modification technology. In this study, the physical and chemical properties, toxicity, and proliferation of adipose stem cells of composite graphene-coated titanium alloy (Gr–Ti) were investigated using 3D-printed titanium alloy as a material model. Physical and chemical property tests confirmed that 3D printing could produce porous titanium alloy materials; the compressive strength and elastic modulus of the titanium alloy scaffolds were 91 ± 3 MPa and 3.1 ± 0.4 GPa, matching the elastic modulus of normal bone tissue. The surface characterization shows that graphene can be coated on titanium alloy by a micro-arc oxidation process, which significantly improves the surface roughness of titanium alloy. The roughness factor (Ra) of the Ti stent was 4.95 ± 1.12 μm, while the Ra of the Gr–Ti stent was 6.37 ± 0.72 μm. After the adipose stem cells were co-cultured with the scaffold for 4 h and 24 h, it was found that the Gr–Ti scaffold could better promote the early cell adhesion. CCK-8 tests showed that the number of ADSCs on the G–Ti scaffold was significantly higher than that on the Ti scaffold (p < 0.01). The relative growth rate (RGR) of ADSCs in Gr–Ti was grade 0–1 (non-toxic). In the in vivo experiment of repairing a critical bone defect of a rabbit mandible, the bone volume fraction in the Gr–Ti group increased to 49.42 ± 3.28%, which was much higher than that in the Ti group (39.76 ± 3.62%) (p < 0.05). In conclusion, the porous graphene–titanium alloy promotes the proliferation and adhesion of adipose stem cells with multidirectional differentiation potential, which has great potential for the application of bone tissue engineering in repairing bone defects in the future.
Highlights
Maxillofacial bone defects caused by trauma and tumors are major challenges faced by plastic surgeons, but satisfactory repair materials have not been found yet [1,2]
The results showed that graphene coating could promote the proliferation of Adipose-derived stem cells (ADSCs) on porous titanium alloy scaffolds
The results show that the roughness factor (Ra) of the graphene-coated titanium alloy (Gr–Ti) scaffold was 6.37 ± 0.72 μm, and the surface roughness of the Ti scaffold was 4.95 ± 1.12 μm, indicating that the graphene coating was successfully prepared on the surface of the porous titanium alloy by micro-arc oxidation technology
Summary
Maxillofacial bone defects caused by trauma and tumors are major challenges faced by plastic surgeons, but satisfactory repair materials have not been found yet [1,2]. The surrounding bone tissue is absorbed, and even leads to the loosening or fracture of the implant, resulting in the instability of the combination of materials and tissues [5,6] To solve these problems, different titanium alloy surface modification techniques have been proposed to meet the requirements of clinical application, such as implant surface coating, which is loaded with bioactive molecules or drugs to modify the implant surface to promote osseointegration at the implant–bone interface. The porous structure of 3D printing can affect the overall density, strength, and elastic modulus of the metal implant, and adjust the pore size and porosity to match the mechanical properties of the host bone tissue, and the stress shielding effect can be effectively reduced or eliminated [10]. The pores of three-dimensional traffic can enable the free transmission of body fluids, bring nutrients to the growth of new bone, take away metabolic waste, promote the regeneration and reconstruction of tissue, and accelerate the whole repair process [11]
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