Laser Induced Micro/Nano …
451
attributed to the local effect during laser irradiation. The LIPSS on both the alloys
does not produce any cell cytotoxicity and pro-inflammatory effects, further, the
increase in cell proliferation was noticed in 15 days.
The micro-dot matrix induced by the femtosecond laser on pure Mg at air and
hydroxyapatite suspension revealed the different characteristic features on the treated
surface which altered the calcium phosphate deposition in physiological solution
[57]. The surface was more hydrophilic in nature when the laser power was high
and found to be favorable for the bone-like calcium phosphate deposition on the
surface. Furthermore, the Ca and P deposition during the laser processing was due
to the vaporization of water molecules in the processing regions, thus the concentration of ions was greatly increased and crystallized in the ablation area. During
laser irradiation, the electrons are ejected from the Ti surface produced the positive
charge, combined with the negatively charged PO 4
3− ions present in the solution
subsequently reacted with Ca
2+ ions to form Ca 3 (PO 4 ) 2 . Ti surface consisted of
micro-holes with the inner wall covered with the mastoid-like shape after the laser
processing in the HA solution which could expose more fresh Ti surface and allow
the Ca and P deposition with tight chemical bonding to the surface compared with
the surface which produced in the air atmosphere, therefore, enhanced the biological
response.
The nanosecond pulsed laser treatment on pure Ti with different defocus distance
produced a significant variation in the surface microtopography and the amount of
-OH group, which played a key role in accelerating the hydroxyapatite deposition
from the physiological solution for the bone healing process. The defocus distances
of 0- and 2-mm during laser processing produced pocket-like micro topographical
structures along the processing trace, however, the surface was relatively smooth
for the defocus distance of 4 mm. A pocket-like nano topographies accelerated the
microspherical hydroxyapatite composed of plate-like and needle-like crystals depositions (Ca/P ratio: 1.5) during 1-2 weeks of immersion. The shorter defocus distance
could be responsible for the higher -OH groups on the processed surface and accelerated the hydroxyapatite deposition and cell adhesion behavior [58]. The Ti64 alloy
produced by the SLM technique was subsequently subjected to the electrochemical
anodization to produce macro-micro-nanoscale hierarchical surfaces to enhance their
biocompatibility [59]. The anodized samples were composed of TNT arrays with an
average diameter of about 60 μm, however, SLM alloy had micro-scale features
and SLM-TNT had nanoscale features. This results in lower contact angle values,
higher protein adsorption, and more MSC cell adsorption. Cell proliferation on the
anodized samples was also higher, in particular, SLM-TNT had a higher proliferation
rate compared to PO-TNT alloy after 120 h of incubation. These results clearly show
that the surface topography plays a dominant role in improving the biocompatibility.
Laser-induced surface texturing with various micro/nano textures influences the
antibacterial properties of implant alloys due to the variations in the wettability, and
chemical composition. The femtosecond laser treatment on 316L SS was carried out
by Lutey et al. to produce nano spikes, LIPSS, and nano-pillars with varying the
pulse energy of 19.1, 1.01 and 1.46 μJ, respectively [5]. The surface with an average
areal surface roughness of 8.6 μm, 90 nm, and 60 nm had a static contact angle value
451
attributed to the local effect during laser irradiation. The LIPSS on both the alloys
does not produce any cell cytotoxicity and pro-inflammatory effects, further, the
increase in cell proliferation was noticed in 15 days.
The micro-dot matrix induced by the femtosecond laser on pure Mg at air and
hydroxyapatite suspension revealed the different characteristic features on the treated
surface which altered the calcium phosphate deposition in physiological solution
[57]. The surface was more hydrophilic in nature when the laser power was high
and found to be favorable for the bone-like calcium phosphate deposition on the
surface. Furthermore, the Ca and P deposition during the laser processing was due
to the vaporization of water molecules in the processing regions, thus the concentration of ions was greatly increased and crystallized in the ablation area. During
laser irradiation, the electrons are ejected from the Ti surface produced the positive
charge, combined with the negatively charged PO 4
3− ions present in the solution
subsequently reacted with Ca
2+ ions to form Ca 3 (PO 4 ) 2 . Ti surface consisted of
micro-holes with the inner wall covered with the mastoid-like shape after the laser
processing in the HA solution which could expose more fresh Ti surface and allow
the Ca and P deposition with tight chemical bonding to the surface compared with
the surface which produced in the air atmosphere, therefore, enhanced the biological
response.
The nanosecond pulsed laser treatment on pure Ti with different defocus distance
produced a significant variation in the surface microtopography and the amount of
-OH group, which played a key role in accelerating the hydroxyapatite deposition
from the physiological solution for the bone healing process. The defocus distances
of 0- and 2-mm during laser processing produced pocket-like micro topographical
structures along the processing trace, however, the surface was relatively smooth
for the defocus distance of 4 mm. A pocket-like nano topographies accelerated the
microspherical hydroxyapatite composed of plate-like and needle-like crystals depositions (Ca/P ratio: 1.5) during 1-2 weeks of immersion. The shorter defocus distance
could be responsible for the higher -OH groups on the processed surface and accelerated the hydroxyapatite deposition and cell adhesion behavior [58]. The Ti64 alloy
produced by the SLM technique was subsequently subjected to the electrochemical
anodization to produce macro-micro-nanoscale hierarchical surfaces to enhance their
biocompatibility [59]. The anodized samples were composed of TNT arrays with an
average diameter of about 60 μm, however, SLM alloy had micro-scale features
and SLM-TNT had nanoscale features. This results in lower contact angle values,
higher protein adsorption, and more MSC cell adsorption. Cell proliferation on the
anodized samples was also higher, in particular, SLM-TNT had a higher proliferation
rate compared to PO-TNT alloy after 120 h of incubation. These results clearly show
that the surface topography plays a dominant role in improving the biocompatibility.
Laser-induced surface texturing with various micro/nano textures influences the
antibacterial properties of implant alloys due to the variations in the wettability, and
chemical composition. The femtosecond laser treatment on 316L SS was carried out
by Lutey et al. to produce nano spikes, LIPSS, and nano-pillars with varying the
pulse energy of 19.1, 1.01 and 1.46 μJ, respectively [5]. The surface with an average
areal surface roughness of 8.6 μm, 90 nm, and 60 nm had a static contact angle value