Introduction The surface characteristics of an implantable material play an important role in governing the cellular response. The objective of modifying the surface characteristics of a biomaterial by means of a surface treatment, such as, ion implantation, sputter coating, thermal oxidation or anodic oxidation is to improve its corrosion resistance, wear properties as well as its biocompatibility [1]. Anodic oxidation is one of the commonly used methods that can be successfully used to

more »

... these properties for biomedical applications [2-7]. The study of the interface between a living cell and a biomaterial is crucial in understanding the mechanism of cellular adhesion. Parameters such as surface roughness, surface chemistry, oxide thickness and the presence of contaminants on the surface are known to affect this interface and subsequently the biological response both in-vivo and in-vitro [8-11]. Such an interface was investigated in-vitro by Davis et al. [12] and de Bruijn et al. [13] for conventional titanium alloys, where the interface formed comprised of a layer of Ca and P rich globular deposits, adjacent to the implant surface over which collagen fibers were deposited. A similar interface was also created in-vivo by others [14]. There has been an increasing interest over the last decade to develop alloys containing β stabilizing elements such as molybdenum, niobium, tantalum, zirconium that can improve the alloy strength and lower the modulus mismatch between the ductile bone and the comparatively brittle implant material, thus minimizing the stress shielding [15-20]. Ti15Mo alloy is a metastable β alloy whose basic metallurgy, mechanical and corrosion resistance properties have been thoroughly described in the metallurgical literature, especially its biocompatible advantages [21-23]. Ti15Mo alloy has a body centered cubic β microstructure with a higher strength over α and α+β alloys. It has low values of elastic modulus and stiffness which makes it beneficial for dental applications. The work described here is part of a study in which Ti15Mo alloy was surface modified by anodic oxidation at 1 V in phosphate buffer saline solution and characterized for its cellular response and surface chemistry. The investigation was also performed for the mixed Ti6Al4V and the α Ti2 alloys for comparison. The surface modified alloys have been characterized for their corrosion behavior at various anodic potentials in our previous studies [24-25]. A value of 1 V as the anodization potential in the passivation range was chosen since it has been shown by Black that the potential value of a metallic biomaterial may generically vary up to 1.2 V vs SCE in the human body [26]. Experimental Materials Preparation Titanium alloy grades, Ti15Mo (0.05%C, 0.1%Fe, 0.015%H, 0.01%N, 0.15%O, 15%Mo & 84.67%Ti), Ti6Al4V (0.1%C, 0.2%Fe, 0.015%H, 0.03%N, 0.2%O, 6%Al, 4%V & 89.45%Ti) and Ti2 (0.1%C, 0.3%Fe, 0.015%H, 0.03%N, 0.25%O & 99.30%Ti), were used for the present investigation. Available cuboidal and cylindrical rods were machined to cylindrical samples of 5 mm in diameter and 5 mm in height with a hole 2 mm deep on one of the flat faces with a tap and drill #3-48. The hole was drilled to attach the specimens to the electrode holder in order to carry out the electrochemical anodization of the samples at 1 V. The exposed surface of the specimens was finished and polished with different grades of SiC grit papers (up to 2400 grit) and polished using a diamond abrasive wheel, washed with double distilled water and acetone. Phosphate buffer saline solution (0.137M sodium chloride, 0.0027M potassium chloride and 0.01M phosphate buffer) of pH 7.4 was used to carry out the electrochemical anodization at 1V for all alloys. _______________________________________________________________________________________