Femtosecond Laser Surface Micro- and Nanotexturing …
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at the three-phase boundary (solid, liquid, and fluid) and the horizontal solid surface.
CA is measured on the side of the liquid. We used the sessile drop method for
CA evaluation, when the distilled water droplet is deposited with a syringe onto the
sample surface. CA is measured from the drop shape surface using the image analysis
software.
Figure 9 presents the examples of droplets on surfaces of Zr and Ti–Zr alloys
mechanically polished or SLE processed before femtosecond laser treatment.
It is found that the surfaces with greater roughness exhibit greater hydrophobicity
(contact angles in the range of 123°–128°). For defect-free surfaces and quasiperiodic
structures, the contact angles are to be in the range of 56°–61° that indicates a greater
hydrophilicity of such surfaces. The increase in the surface roughness, surface energy,
and chemical composition (formation of surface oxides) increases the wettability of
metal surfaces.
Resazurin sodium salt assay has been used to access cell viability and proliferation
rate on days 1, 3, and 7 after cell seeding. Media was removed from each well and
washed with PBS twice. 1 ml of resazurin sodium salt solution was added to each
scaffold and incubated for 4 h. Three aliquots of 200 µl of resazurin sodium salt
solution were collected from each scaffold and read at a wavelength of 620 nm in
a colorimetric plate reader (Multiskan FC Microplate Photometer, Thermo Fisher
Scientific) to obtain baseline values of colorimetric absorbance. Cell viability was
calculated as a % of resazurin reduction compared to pure resazurin sodium salt
solution. We selected the most promising Zr samples and Ti–Zr alloy samples for the
biocompatibility (see Figs. 10 and 11). We can suppose that the biological response
of both metal and alloy samples is similar to the studied parameters of treatment.
Meanwhile, the obtained data are promising for the usage of laser-treated surfaces
for dental applications.
6 Conclusions
Periodic and ununiform rough structures have been obtained on the surfaces of metal
(Zr), alloy (Ti–Zr), and zirconia ceramics under a powerful femtosecond laser irradiation of fundamental (800 nm) and third harmonics (266 nm). The highest quality
processing of studied implant specimens has been achieved at higher radiation power
densities at higher scanning velocities. At an increase of the distance between the
specimen and the lens focus, the height of the grooves profile and the grating period
decrease. Laser texturing can change the wettability of the samples. The preliminary
experiments on cell viability confirm the effect of biofunctionalization of treated
surfaces.
Hence, among commercially available techniques used for the implant surface
modification, the femtosecond laser treatment is promising due to its flexibility,
simplicity, high reproducibility, and application for a wide range of materials such
as metals, metal alloys, and ceramics.
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at the three-phase boundary (solid, liquid, and fluid) and the horizontal solid surface.
CA is measured on the side of the liquid. We used the sessile drop method for
CA evaluation, when the distilled water droplet is deposited with a syringe onto the
sample surface. CA is measured from the drop shape surface using the image analysis
software.
Figure 9 presents the examples of droplets on surfaces of Zr and Ti–Zr alloys
mechanically polished or SLE processed before femtosecond laser treatment.
It is found that the surfaces with greater roughness exhibit greater hydrophobicity
(contact angles in the range of 123°–128°). For defect-free surfaces and quasiperiodic
structures, the contact angles are to be in the range of 56°–61° that indicates a greater
hydrophilicity of such surfaces. The increase in the surface roughness, surface energy,
and chemical composition (formation of surface oxides) increases the wettability of
metal surfaces.
Resazurin sodium salt assay has been used to access cell viability and proliferation
rate on days 1, 3, and 7 after cell seeding. Media was removed from each well and
washed with PBS twice. 1 ml of resazurin sodium salt solution was added to each
scaffold and incubated for 4 h. Three aliquots of 200 µl of resazurin sodium salt
solution were collected from each scaffold and read at a wavelength of 620 nm in
a colorimetric plate reader (Multiskan FC Microplate Photometer, Thermo Fisher
Scientific) to obtain baseline values of colorimetric absorbance. Cell viability was
calculated as a % of resazurin reduction compared to pure resazurin sodium salt
solution. We selected the most promising Zr samples and Ti–Zr alloy samples for the
biocompatibility (see Figs. 10 and 11). We can suppose that the biological response
of both metal and alloy samples is similar to the studied parameters of treatment.
Meanwhile, the obtained data are promising for the usage of laser-treated surfaces
for dental applications.
6 Conclusions
Periodic and ununiform rough structures have been obtained on the surfaces of metal
(Zr), alloy (Ti–Zr), and zirconia ceramics under a powerful femtosecond laser irradiation of fundamental (800 nm) and third harmonics (266 nm). The highest quality
processing of studied implant specimens has been achieved at higher radiation power
densities at higher scanning velocities. At an increase of the distance between the
specimen and the lens focus, the height of the grooves profile and the grating period
decrease. Laser texturing can change the wettability of the samples. The preliminary
experiments on cell viability confirm the effect of biofunctionalization of treated
surfaces.
Hence, among commercially available techniques used for the implant surface
modification, the femtosecond laser treatment is promising due to its flexibility,
simplicity, high reproducibility, and application for a wide range of materials such
as metals, metal alloys, and ceramics.