Silicon-Doped Titanium Dioxide Nanotubes Promoted Bone Formation on Titanium Implants.

Xijiang Zhao,Junying Sun,Xuanyong Liu,Tao Wang,Shi Qian,Bin Li

doi:10.3390/ijms17030292

Abstract

While titanium (Ti) implants have been extensively used in orthopaedic and dental applications, the intrinsic bioinertness of untreated Ti surface usually results in insufficient osseointegration irrespective of the excellent biocompatibility and mechanical properties of it. In this study, we prepared surface modified Ti substrates in which silicon (Si) was doped into the titanium dioxide (TiO2) nanotubes on Ti surface using plasma immersion ion implantation (PIII) technology. Compared to TiO2 nanotubes and Ti alone, Si-doped TiO2 nanotubes significantly enhanced the expression of genes related to osteogenic differentiation, including Col-I, ALP, Runx2, OCN, and OPN, in mouse pre-osteoblastic MC3T3-E1 cells and deposition of mineral matrix. In vivo, the pull-out mechanical tests after two weeks of implantation in rat femur showed that Si-doped TiO2 nanotubes improved implant fixation strength by 18% and 54% compared to TiO2-NT and Ti implants, respectively. Together, findings from this study indicate that Si-doped TiO2 nanotubes promoted the osteogenic differentiation of osteoblastic cells and improved bone-Ti integration. Therefore, they may have considerable potential for the bioactive surface modification of Ti implants.

Highlights

Taking advantage of their excellent biocompatibility and mechanical properties, titanium (Ti) and its alloys have been extensively used in orthopedic and dental applications these days [1,2]
Ti substrates that were decorated with TiO2 nanotubes at the surface and further doped with Si using plasma immersion ion implantation technology have been prepared
It was found that TiO2-NT and Si–TiO2-NT substrates promoted the adhesion and proliferation of pre-osteoblastic MC3T3-E1 cells compared to Ti alone

Summary

Introduction

Taking advantage of their excellent biocompatibility and mechanical properties, titanium (Ti) and its alloys have been extensively used in orthopedic and dental applications these days [1,2]. The intrinsic bioinertness of untreated Ti surface usually results in insufficient bone formation and consequent osseointegration, which increases the risk of instability after surgical procedures including total joint replacement such as total hip arthroplasty (THA) or spinal fusion [3,4]. Introducing anodic titanium dioxide (TiO2) nanotubes onto the Ti surface is among one of the approaches. A highly ordered TiO2 nanotube array with the lateral dimension within the sub-100 nm region forms on the surface of Ti substrate when it is anodized in fluoride-containing electrolytes [15,16]. The growth of osteoblasts was accelerated by as much as 300%–400% when grown on anodic TiO2 nanotubes compared to the osteoblasts grown on unanodized Ti [17]. Cells grown on TiO2 nanotube surfaces showed stronger ALP activity and more calcium deposition [18,19]

Methods

Results

Discussion

Conclusion