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.