Polydopamine coating promotes early osteogenesis in 3D printing porous Ti6Al4V scaffolds

Abstract

Background: Titanium implants are widely used in orthopedic and dental for more than 30 years. Its stable physicochemical properties and mechanical strength are indeed appropriate for implantation. However, the Bioinertia oxidized layer and higher elastic modulus often lead to the early implantation failure. Methods: In this study, we proposed a simple design of porous structure to minimize the disparity between scaffold and natural bone tissue, and introduced a one-step reaction to form a polydopamine (PDA) layer on the surface of titanium for the purpose of improving osteogenesis as well. The porous scaffolds with pore size of 400 μm and porosity of 44.66% were made by additive manufacturing. The cell behavior was tested by seeding MC3T3-E1 cells on Ti6Al4V films for 15 days. The biomechanical properties were then analyzed by finite element (FE) method and the in vivo osteogenesis effect was accordingly evaluated by implanting the scaffolds for 5 weeks in rabbits. Results: According to the achieved results, it was revealed that the immersion for 40 min with dopamine could significantly improve the cell adhesion. The proposed method for design of porous structure can avoid the stress shielding effect and bone growth inside the PDA coating scaffolds, which were observed at the early stage of bone healing process. Conclusions: It can be concluded that the proposed PDA coating method is effective in promoting early osteogenesis, as well as being easy to operate, and can be helpful in the future clinical application of titanium implants.

A systematic review of preclinical in vivo testing of 3D printed porous Ti6Al4V for orthopedic applications, part I: Animal models and bone ingrowth outcome measures

“…Researchers further explored HA in the form of composites, with studies reporting improved bone ingrowth for HA doped with magnesium, 49 polydopamine, 45 silicon, 59 or strontium 59 compared to uncoated controls, though the silicon and strontium groups did not show the same improvement when compared to undoped HA coatings 59 . Aside from HA, polydopamine coatings, 48,52 titanium copper and titanium copper nitride films, 37 growth factor‐doped fibrin glue, 51 and strontium‐laden nanotube coatings 55 also showed success in increasing 3DP pTi bioactivity. Instead of coatings, one study by Li et al used surface heat treatments to induce material phase transformations, 53 reporting that samples treated at 950 and 1000°C were associated with higher rates of bone formation, thicker bone trabeculae, and greater push‐out loads 53 .…”

Biomaterials for bone regeneration: an orthopedic and dentistry overview

“…For bone regeneration, a scaffold should be biodegradable and biocompatible, as well as having osteoconductive, osteoinductive, and osteogenic properties ( 4 ). In addition, it is desirable that it provides an appropriate exchange of nutrients, promotes vascularization and bone ingrowth, and has a pore size ranging from 100 to 500 µm ( 5 ).…”

How Does Scaffold Porosity Conduct Bone Tissue Regeneration?

“…[158] Although 100 μm is acceptable, a pore size of at least 300 μm is suggested for new bone formation, [159] and the pore size of 400 μm is optimal for vascularization during osteogenesis. [160] A specialized study showed that scaffold pore sizes larger than 390 μm with upper limit of 590 μm are more able to enhance bone tissue formation. [161] The strut thickness and microporosity can also affect the cell penetration and tissue ingrowth in the scaffold.…”