The effects of femtosecond laser-textured Ti-6Al-4V on wettability and cell response

• Wettability of Ti-6Al-4V was studied versus laser texturing, time and storage environment after laser treatment.
• The anisotropy of the cell spreading and the individual orientation of the cells on the biomaterial were investigated.
• Characteristic lengths of the multiscale textures were determined in function of the murine mesenchymal stem cells behavior

To study the biological activity effects of femtosecond laser-induced structures on cell behavior, TA6V samples were micro-textured with focused femtosecond laser pulses generating grooves of various dimensions on the micrometer scale (width: 25–75 μm; depth: 1–10 μm). LIPSS (Laser Induced Periodic Surface Structures) were also generated during the laser irradiation, providing a supplementary structure (sinusoidal form) of hundreds of nanometers at the bottom of the grooves oriented perpendicular (⊥ LIPPS) or parallel (// LIPPS) to the direction of these grooves. C3H10 T1/2 murine mesenchymal stem cells were cultivated on the textured biomaterials. To have a preliminary idea of the spreading of biological media on the substrate, prior to cell culture, contact angle measurement were performed. This showed that the post-irradiation hydrophilicity of the samples can decrease with time according to its storage environment. The multiscale structuration either induced a collaborative or a competitive influence of the LIPSS and grooves on the cells. It has been shown that cells individually and collectively were most sensitive to microscale grooves which were narrower than 25 μm and deeper than 5 μm with ⊥ LIPPS. In some cases, cells were individually sensitive to the LIPSS but the cell layer organization did not exhibit significant differences in comparison to a non-textured surface. These results showed that cells are more sensitive to the nanoscale structures (LIPSS), unless the microstructures's size is close to the cell size and deeper than 5 μm. There, the cells are sensitive to the microscale structures and go on spreading following these structures.

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