Prolonged Biomolecule Release from Titanium Surfaces via Titania Nanotube Arrays

Abstract

Surface modifications containing active biomolecules in order to minimize the failure of titanium implants used in hard tissue repair is one of the most frequently studied subjects in recent years. In the last decade, it has been investigated that nanoscale tubular spaces on the titanium surface can be used as a local drug release reservoir so that the molecule can be loaded into the implant structure without the need for any chemical binder or polymeric coating. It is possible to obtain one-dimensional structures that can be grown by electrochemical anodic oxidation by controlling the diameters of less than 100 nanometers on titanium metal surfaces. The major disadvantage of biomolecules released from titania nanotube structures to the environment is the hard control of release kinetics and more than half of the loading amount releases in the first few hours of interaction with the biological fluid. Although the studies on controlling the kinetics have been tried to overcome by covering the nanotube arrays with barriers such as polymer structures, the risk of delamination of the polymers from the surface during implantation brings additional problems. In this manuscript, vancomycin and bovine serum albumin were loaded into titania nanotubes formed by anodic oxidation technique on titanium metal plates and the tube ends has been narrowed by gold sputtering technique. With this narrowing at the tube-ends, the length of the release time and the change in diameter according to the hydrodynamic diameter of the released biomolecule were investigated. It is seen that the increased gold sputtering time prolongs the release rate of biomolecules and offers a promising approach for sustained local drug releasing implants.