Femtosecond laser-induced nanoporous layer for enhanced osteogenesis of titanium implants

https://doi.org/10.1016/j.msec.2021.112247Get rights and content

Highlights

  • Young's modulus and Vickers hardness of titanium surface were reduced by femtosecond laser machining

  • Simulations show that femtosecond laser can cause the formation of holes in the subsurface layer of titanium

  • A 40 nm porous layer was successfully prepared on the subsurface layer of titanium

  • The surface with low Young's modulus was more conducive to cell proliferation and osteogenic differentiation

Abstract

The osteogenic activity of medical metal can be improved by lowering its surface stiffness and elastic modulus. However, it is very difficult to directly reduce the elastic modulus of medical metal surfaces. In this paper, with selected parameters, the titanium surface was treated via femtosecond laser irradiation. Micro indentation revealed that the femtosecond laser ablation can effectively reduce the surface Young's modulus and Vickers hardness of titanium. Besides, In order to explain the mechanical properties of degradation of titanium surface, Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) was used to simulate the process of laser ablation process of titanium surface, and it was found that after the ablation of titanium surface, voids were produced in the subsurface layer. The simulation showed that the voids are formed by the cavitation of metastable liquid induced by high tensile stress and high temperature during femtosecond laser irradiation. Subsurface voids with a thickness of about 40 nm were observed under the oxide layer in the experiment. Cell experiments showed that the surface with low Young's modulus was more conducive to cell proliferation and osteogenic differentiation.

Keywords

Nanoporous layer
Implant
Femtosecond laser
Molecular dynamics simulation
Surface modification
Osteogenesis

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1

The two authors share the co-first authorship.

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