Laser Induced Micro/Nano …
449
had a significant increase in contact angle value (~ 115°) and it was attributed to
the directional nature of the surface. The cell attachment and proliferation were
strongly affected by the surface nature, and the cell adhesion was improved with
higher surface roughness. However, the proliferation rate was better for the lower
surface roughness samples. The higher cell proliferation rate was noticed for the
polished and sub-micron textured samples. These findings suggested that the surface
needs to be prepared by combining the micro-scale structures and sub-micro features
that are possible by the femtosecond lasers, this, in turn, facilitates the mechanical
anchoring of the bone, cell adhesion, and proliferation. In another study, the laser
patterning on Co-Cr alloy (51%Co, 20%Cr, 15%W, 10%Ni, and 3%Fe) was carried
out using a direct laser interference patterning (DLIP) with different periodicities
(≈ 3, 10, 20, and 32 μm) and depths (≈ 20 and 800 nm) which significantly altered
the surface wettability, platelet adhesion, and human umbilical vein endothelial cell
(HUVEC) adhesion and spreading performances [54]. The wettability of the laser
patterned surfaces decreased compared to the control samples, which was attributed
to the surface roughness and variation in the surface chemical composition. The crystalline Cr 2 O 3 and Co 3 O 4 phases were transformed to amorphous phases after hightemperature laser irradiation. Laser patterns with higher depth induced HUVEC’s
elongation, alignment, and migration due to the topographical patterns. Furthermore,
the platelet adhesion was reduced on the patterned surface was attributed to the oxide
layer formation which affected the surface thrombogenicity.
The femtosecond laser was used to produce the micro pits consisted of nanoripples and nano textures with nano-ripples on Ti64 alloy and the response of
mesenchymal stem cells (MSC, C3H10T1/2) on these surfaces was investigated
by Dumas et al. [55]. The micro pits with a diameter of about 30 μm and depth of
800 nm consisted of nano ripple 1) at the bottom of the pit and 2) around the tip of the
pit with a distance of about 5 μm between the pits (Texture A and B in Fig. 3a) which
revealed a difference in the cell spreading, and attachment behavior compared to the
surface containing only nano ripple texture (Texture C). Contact angle values of the
texture A and B were similar to the polished sample, however, texture C was more
hydrophilic nature. Furthermore, the cell sizes were smaller on the textured surfaces,
and the arrangement of the actin fiber was varied depending on the morphologies
compared to the polished sample. The dynamic cell spreading studies revealed that
the MSCs spread about 2 times faster on the textures A and B compared to the surface
with only nano-ripples. Interestingly, cell mobility was also about 40% higher for
the textures A and C than the texture B and smooth surface. The textured surfaces
had better osteogenesis compared to the polished surface which was attributed to
the alteration in cell shape, focal contacts, and the cytoskeletal organization initiated
during the minutes to hours after the cell adhesion. The laser textured surfaces inhibited the adipogenesis and enhanced the osteogenesis due to the loss of the cellular
shape compared to the polished samples.
The influences of surface micro/nano topographic surfaces of pure Ti on the cell
adhesion and differentiation behavior was investigated by Chen et al. [4]. Microgrid
patterns with the dimensions of 5 μm wide and 1 μm deep grooves separated by
6 μm ridges were developed on Ti (Fig. 3b) and the nano grid surface depth was
449
had a significant increase in contact angle value (~ 115°) and it was attributed to
the directional nature of the surface. The cell attachment and proliferation were
strongly affected by the surface nature, and the cell adhesion was improved with
higher surface roughness. However, the proliferation rate was better for the lower
surface roughness samples. The higher cell proliferation rate was noticed for the
polished and sub-micron textured samples. These findings suggested that the surface
needs to be prepared by combining the micro-scale structures and sub-micro features
that are possible by the femtosecond lasers, this, in turn, facilitates the mechanical
anchoring of the bone, cell adhesion, and proliferation. In another study, the laser
patterning on Co-Cr alloy (51%Co, 20%Cr, 15%W, 10%Ni, and 3%Fe) was carried
out using a direct laser interference patterning (DLIP) with different periodicities
(≈ 3, 10, 20, and 32 μm) and depths (≈ 20 and 800 nm) which significantly altered
the surface wettability, platelet adhesion, and human umbilical vein endothelial cell
(HUVEC) adhesion and spreading performances [54]. The wettability of the laser
patterned surfaces decreased compared to the control samples, which was attributed
to the surface roughness and variation in the surface chemical composition. The crystalline Cr 2 O 3 and Co 3 O 4 phases were transformed to amorphous phases after hightemperature laser irradiation. Laser patterns with higher depth induced HUVEC’s
elongation, alignment, and migration due to the topographical patterns. Furthermore,
the platelet adhesion was reduced on the patterned surface was attributed to the oxide
layer formation which affected the surface thrombogenicity.
The femtosecond laser was used to produce the micro pits consisted of nanoripples and nano textures with nano-ripples on Ti64 alloy and the response of
mesenchymal stem cells (MSC, C3H10T1/2) on these surfaces was investigated
by Dumas et al. [55]. The micro pits with a diameter of about 30 μm and depth of
800 nm consisted of nano ripple 1) at the bottom of the pit and 2) around the tip of the
pit with a distance of about 5 μm between the pits (Texture A and B in Fig. 3a) which
revealed a difference in the cell spreading, and attachment behavior compared to the
surface containing only nano ripple texture (Texture C). Contact angle values of the
texture A and B were similar to the polished sample, however, texture C was more
hydrophilic nature. Furthermore, the cell sizes were smaller on the textured surfaces,
and the arrangement of the actin fiber was varied depending on the morphologies
compared to the polished sample. The dynamic cell spreading studies revealed that
the MSCs spread about 2 times faster on the textures A and B compared to the surface
with only nano-ripples. Interestingly, cell mobility was also about 40% higher for
the textures A and C than the texture B and smooth surface. The textured surfaces
had better osteogenesis compared to the polished surface which was attributed to
the alteration in cell shape, focal contacts, and the cytoskeletal organization initiated
during the minutes to hours after the cell adhesion. The laser textured surfaces inhibited the adipogenesis and enhanced the osteogenesis due to the loss of the cellular
shape compared to the polished samples.
The influences of surface micro/nano topographic surfaces of pure Ti on the cell
adhesion and differentiation behavior was investigated by Chen et al. [4]. Microgrid
patterns with the dimensions of 5 μm wide and 1 μm deep grooves separated by
6 μm ridges were developed on Ti (Fig. 3b) and the nano grid surface depth was