Mussel-inspired silver-nanoparticle coating on porous titanium surfaces to promote mineralization
Biomaterials with high porosity for bone ingrowth facilitate the osseointegration of implants. However, this porosity structure is also favorable for bacterial colonization and biofilm formation, and hampers osseointegration on implant surfaces. The objective of the study was to establish a porous surface on titanium implants with antibacterial activity, enhanced mineralization and then good osteoblast-biocompatibility. A uniform, 3-dimensional, microporous structure was prepared by alkaline treatment on a titanium implant surface. Subsequently, the surface was coated with dopamine and silver nanoparticles using dopamine and silver nitrate solutions. The results of SEM, EDS, XPS, and water contact angle tests confirmed that the surface had been successfully coated with dopamine and silver nanoparticles with sizes of 30–50 nm. More mineralization happened on the surface with this coating than on the alkaline-treated surface after incubation with calcification solution for one week, which led to a rapid decrease of silver release. Antibacterial tests indicated that the coating inhibited bacterial colonization on them and growth around these samples, indicating that the coating eliminates the shortcoming of porous structure which renders the implant extremely susceptible to biomaterial-associated infection. Besides, this coating did not favor osteoblast attachment, proliferation and differentiation, however we found that the mineralized surface of this coating stimulated the proliferation of osteoblasts and enhanced the activity of alkaline phosphatase. Therefore, we conclude that the coating with dopamine and AgNPs can be effective against bacterial infections and facilitate mineralization during the early post-operative period and then can promote osseointegration due to the good osteoblast-biocompatibility of the mineralized surface.