Surface engineering of titanium with simvastatin-releasing polymer nanoparticles for enhanced osteogenic differentiation

We describe a novel approach for surface engineering of titanium (Ti) with polymer nanoparticles that can sustainably release an osteogenic compound, simvastatin (SV). The SV-loaded nanoparticles (SV-GC-CA) were prepared by self-assembly of 5 beta-cholanic acid-conjugated glycol chitosan (GC-CA) in the presence of SV. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) analyses showed that the SV-GC-CA nanoparticles had a hydrodynamic diameter of 371.4 nm with a spherical shape. The surface engineering of Ti was performed by pre-treatment of Ti surface with polydopamine (PD) coatings, followed by immobilization of the SV-GC-CA nanoparticles. The immobilization of the SV-GC-CA nanoparticles onto PD-treated Ti surfaces could be achieved by a simple dipping method in an aqueous solution. The successful immobilization of the SV-GC-CA nanoparticles onto Ti surfaces was confirmed by field-emission scanning electron microscopy (FE-SEM), and the density of immobilized nanoparticles could be controlled. SV was sustainably released for up to 20 days, and the release rate was dependent on the loading amount of SV. The Ti substrate functionalized with SV-releasing nanoparticles significantly promoted alkaline phosphatase (ALP) activity of osteoblast-like cells (MC3T3-E1). The surface engineering approach described in this work has an applicability for various medical devices to generate surfaces with improved osteogenic potentials.