Effect of Mo and space holder content on microstructure, mechanical and corrosion properties in Ti6AlxMo based alloy for bone implant.

The porous alloys of Ti6Al(3-15)Mo were developed to replace the fractured bone; the alloy consists of 6 wt% of Al which was taken as α the phase stabilizer and (3-15) wt% Mo with an increment of 3 wt% was taken as ß phase stabilizer. The porosity of these fabricated porous alloys was controlled by adjusting volume% of the ammonium bicarbonate (SH). These porous samples were characterized in terms of their microstructure, compressive strength, elastic modulus, energy absorption, ion release and corrosion rate in simulated body fluid (SBF) and these properties are compared with the existing alloys and human bone. The fabricated porous samples were characterized, and the obtained results were analysed as a function of Mo concentration and the volume% of space holder content. Three phases were found in the microstructure: α, α2 and ß phase of titanium. Increase in Mo content from 3 to 15 wt% has increased the volume fraction of ß phase from 7.45% to 64.09% and Kirkendall pores also are observed to be increased with increase in Mo content. α and α2 phase was differentiated by the TEM and phase map of EBSD images. The plateau stress, elastic modulus and energy absorption are observed to be decreased, and the densification strain is observed to be increased with the addition of Mo and SH content. The released ion concentration and corrosion rate are far below the tolerance limits of Ti, Al and Mo elements, in the static immersion test conducted in SBF solution.

Antibacterial and cytocompatibility study of modified Ti6Al4V surfaces through thermal annealing.

Silver coating of different thicknesses ranging from 5 to 20 nm was deposited on the Ti6Al4V substrate using DC sputtering followed by thermal annealing at 750 °C for 15 min in an ambient environment. The surface topography and elemental composition of annealed samples were analyzed using different characterization techniques. The silver ions (Ag+) concentration released from the modified titanium surface was calculated through inductive coupled plasma mass spectroscopy (ICP-MS). The plate counting method was used to quantify the bacteria-killing potential of modified titanium surface against Escherichia coli (E. coli), Staphylococcus aureus (S. aureus), Fluoroquinolones-resistant Salmonella typhi (FRST) and Methicillin-resistant Staphylococcus aureus (MRSA) bacteria. The cell membrane integrity study of E. coli and S. aureus bacterium was done qualitatively using scanning electron microscopy and further confirmed with fluorescence microscopy. Due to thermal annealing, polygonal shaped oxide nanoparticles were formed on the titanium substrate. Moreover, the surface topography of modified titanium surface changes with the thickness of the silver film. In order to check the cytotoxic effect of modified titanium surface, mouse fibroblast cells (NIH3T3) were used for 3­(4,5­dimethylthiazol­2­yl)­2,5­diphenyltetrazolium bromide (MTT) assay. The limited (<35 ppb) Ag+ ion release was noticed for 15 nm silver film which has shown the good bactericidal property and significant growth of fibroblast cells. This study proposes a simple and efficient method to enhance the antibacterial property of Ti6Al4V surfaces to avoid implant-related infection.