Silane-Coating Strategy for Titanium Functionalization Does Not Impair Osteogenesis In Vivo.

Plinio Mendes Senna,Luiz Meirelles,Rafael Coutinho Mello-Machado,Pietro Montemezzi,Carlos Fernando De Almeida Barros Mourão,Altair Antoninha Del Bel Cury,Kayvon Javid

doi:10.3390/ma14071814

Abstract

Silane-coating strategy has been used to bind biological compounds to the titanium surface, thereby making implant devices biologically active. However, it has not been determined if the presence of the silane coating itself is biocompatible to osseointegration. The aim of the present study was to evaluate if silane-coating affects bone formation on titanium using a rabbit model. For this, titanium screw implants (3.75 by 6 mm) were hydroxylated in a solution of H2SO4/30% H2O2 for 4 h before silane-coating with 3-aminopropyltriethoxysilane (APTES). A parallel set of titanium screws underwent only the hydroxylation process to present similar acid-etched topography as a control. The presence of the silane on the surface was checked by x-ray photoelectron spectroscopy (XPS), with scanning electron microscopy (SEM) and atomic force microscopy (AFM). A total of 40 titanium screws were implanted in the tibia of ten New Zealand rabbits in order to evaluate bone-to-implant contact (BIC) after 3 weeks and 6 weeks of healing. Silane-coated surface presented higher nitrogen content in the XPS analysis, while micro- and nano-topography of the surface remained unaffected. No difference between the groups was observed after 3 and 6 weeks of healing (p > 0.05, independent t-test), although an increase in BIC occurred over time. These results indicate that silanization of a titanium surface with APTES did not impair the bone formation, indicating that this can be a reliable tool to anchor osteogenic molecules on the surface of implant devices.

Highlights

Titanium has been widely used as an implant material due to its excellent corrosion resistance, biocompatibility and good mechanical properties such as high tensile strength, high ductility and low density [1]
To reduce early implant failures or complications during healing, especially for patients that present with metabolic diseases such as diabetes, osteoporosis and dental implants in immunocompromised patients [3,4,5,6,7] it is essential to modify the surface properties of titanium in an attempt to promote bone growth and to enhance the direct apposition of new bone in the early stages of the post-implantation period [8,9,10,11]
The titanium screw surfaces that were coated with APTES did not show any changes in surface morphology or roughness (Figures 1 and 2)

Summary

Introduction

Titanium has been widely used as an implant material due to its excellent corrosion resistance, biocompatibility and good mechanical properties such as high tensile strength, high ductility and low density [1]. An implant should allow surface regulation via cellular early-stage attachment for fast reconstruction of the primary implant stability [2,12], which would improve its short and, most importantly, its long-term performance [12]. In this context, the ability to immobilize bioactive molecules onto the titanium surface to create specific cellular responses is of great interest. Since covalently-bonded molecules exhibit greater stability on a surface than physisorbed compounds [13,14,15], especially considering the abrasion of the surface against bone during the implant insertion procedure [16,17], several strategies to chemically modify a titanium surface for the covalent bonding of biological molecules have been described, especially using silane chemistry [18,19,20]

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