Enhanced corrosion, tribocorrosion resistance and controllable osteogenic potential of stem cells on micro-rippled Ti6Al4V surfaces produced by pulsed laser remelting

Abstract

• Pulsed laser remelting was used to generate ripple-like features on Ti6Al4V surfaces. • Laser remelting improved wear, corrosion and tribocorrosion resistance of the surfaces. • Viability and differentiation of hAMSCs were dependent upon the ripple topographies. • Topographies of the rippled structures also influenced the orientation of the cells. Laser-based surface modification methods are employed to augment the surface properties of engineering components. In the presented work, pulsed laser remelting of Ti6Al4V surfaces using a long pulsed laser was used to generate ripple-like micro-features with different feature sizes. The resultant surfaces exhibited improved corrosion and tribocorrosion resistance. Anisotropic wetting characteristics of the laser remelted surfaces led to elongation of water droplets on the surfaces. The osteogenic potential of the surfaces as well as the orientations of human mesenchymal stem cells on the surfaces were dependent on the surface features. On surfaces having 20 μm ripples, differentiation of stem cells towards osteoblastic lineage was higher than that on acid etched surfaces, and the cells were prominently oriented across the ripples, parallel to the laser scanning track. On the other hand, surfaces having 100 μm ripples suppressed the cellular activities on them. While the resistance to corrosion and tribocorrosion of laser remelted surfaces can be attributed to the evolved microstructure and the formation of stable oxide layers, the physical characteristics like topography and wettability dictated cellular behavior on the surfaces. Taken together, the work demonstrates the use of pulsed laser remelting as a simple yet potentially effective route towards manufacturing Ti6Al4V orthopedic implants with improved biofunctionalities.