Optimisation of grafted phosphorylcholine-based polymer on additively manufactured titanium substrate for hip arthroplasty

Despite the tremendous acceptance of additively manufactured (AM) Titanium alloys (Ti6Al4V) in the field of biomedical engineering, the high surface roughness due to partially-melted particles (fabricated in selective laser melting (SLM) process), limits their uses as hip implants. The objective of this study, therefore, is to modify the SLM fabricated Ti6Al4V implant interfaces with 2-Methacryloyloxyethyl phosphorylcholine (MPC) polymer, in the hope of enhancing surface properties and preventing the attachment of the cell simultaneously without affecting the mechanical properties significantly. Three different monomer concentrations were examined to determine the influence of monomer concentrations on polymerisation rate, chain length, and surface properties of the implants. Samples grafted with 0.6 M monomer concentration showed more uniform surface and less surface roughness in comparison with other samples and untreated Ti6Al4V surfaces. 0.6 M monomer concentration was found to be the best option for grafting PMPC to the hip implant interfaces because of its improved surface morphology, surface roughness, polymerisation rate, penetration depth and hardness results. Moreover, cell study on optimal surfaces revealed that PMPC grafted surfaces prevent the implant interfaces from uncontrollable cell attachment which is of utmost importance in smoothing the motion of the hip implant under cyclic loading. Overall, the PMPC grafting demonstrated the potentiality of its application on SLM Ti6Al4V substrate for improved hip arthroplasty performance.