Reduced toxicity and superior cellular response of preosteoblasts to Ti-6Al-7Nb alloy and comparison with Ti-6Al-4V.

There are serious concerns on the toxicity of vanadium in Ti-6Al-4V alloy. In this regard, we describe the biological footprint of Ti-6Al-4V and compare with a viable alternate Ti-6Al-7Nb alloy, in terms of novel experimentation pertaining to cellular activity that include qualitative and quantitative analysis of Feret's diameter of cells, area, and perimeter, and proteins-actin, vinculin, and fibronectin. Interestingly, Ti-6Al-7Nb was characterized by superior cell attachment, proliferation, viability, morphology, and spread, which were significantly different from Ti-6Al-4V alloy. Additionally, immunofluorescence studies demonstrated stronger vinculin signals associated with actin stress fibers in the outer regions of the cells and cellular extensions in Ti-6Al-7Nb alloy. These striking observations suggest enhanced cell-substrate interaction and activity on the surface of niobium-containing titanium alloy. The significant differences in the cellular response between the two alloys clearly point to the determining role of alloying element (Nb versus V) in a conclusive manner. Based on this study, next generation of titanium alloys is proposed to focus on niobium-containing alloy.