Deposition of biphasic calcium phosphate film on laser surface textured Ti–6Al–4V and its effect on different biological properties for orthopedic applications

The present study reports laser surface texturing (LST) of Ti–6Al–4V using a Nd-YAG laser with a particular set of parameters and three different overlapping factors (OF): 0%, 25% and 50%. Biphasic calcium phosphate (BCP) film was deposited on bare as well as textured Ti–6Al–4V specimens by using radio frequency (RF) sputtering. The simultaneous effect of texturing as well as BCP coating on different physical and biological properties was investigated. The study revealed that the surface wettability of bare Ti–6Al–4V enhanced after laser texturing (as contact angle reduced from 89° to 71°-77°). It was further improved upon BCP deposition to make the Ti–6Al–4V superhydrophilic (contact angle ≈ 17°-21°). It was also observed that the surface roughness of bare Ti–6Al–4V significantly increased from Ra ≈ 94 nm to Ra ≈ 0.98–1.84 μm for different micro-dimpled texture substrates. The dimensions of micro-dimpled texture did not change after BCP deposition; however, a non-uniform film is deposited with increase in surface roughness. Protein adsorption was found as a function of surface hydrophobicity, which increased from 5.3 to 7.11 μg/cm2 with the rise in hydrophobicity of modified surfaces. Compared to bare Ti–6Al–4V and BCP deposited bare-Ti-6Al–4V surfaces, the BCP deposited textured surfaces exhibit higher number of well spread MG63 osteoblast cells. For the same surface chemistry, increase in surface area (roughness) improves cellular behavior. With texturing of the substrate, the cell adhered percentage and average cell area improved significantly and BCP-(50% OF)–Ti–6Al–4V was found to have the maximum cell spreading and proliferation. Overall, these findings revealed that a micro-dimpled textured surface followed by BCP film deposition strategy improved the physio-chemical properties of surfaces such as surface roughness and wettability. This in turn enhanced the bioactivity, cell adhesion and proliferation of bone cells (MG63) on modified Ti–6Al–4V surfaces and based on the results we envisage that can be potentially used for orthopedic and dental applications.