452
S. Arthanari et al.
of 160°, 119°, and 140°, respectively. As the size of the E.coli (rod shape, ~ 0.5 μm
diameter and length ~ 2 μm) and S.aureus (spherical shape, ~ 0.5 μm diameter) was
varied, the bacterial adhesion behavior was also varied and the area occupied by the
E.coli and S.aureus are ~ 1 μm
2 /cell and 0.25 μm
2 /cell, respectively. Therefore, the
surfaces with features larger than the bacterial size (spikes) and similar to the bacterial
size (LIPSS and nano-pillars), thus affected bacterial contact and further adhesion.
The retention of the E.coli on the mirror polished and spikes surface was higher as
the surface dimension is larger than the cell size, however, S.aureus adhesion was
inhibited. Interestingly LIPSS and nano-pillars revealed 99.8% and 99.2% for the
E.coli and 84.7% and 79.9% for the S.aureus, respectively. The antibacterial activity
was attributed to both surface wettability and morphological change of the laser
textured specimens. A continuous-wave fiber laser-treated CP-Ti (grade 2), Ti64, and
CoCrMo alloys under the nitrogen atmosphere were tested for the S.aureus adhesion
[60]. The surface of the treated Ti samples was mainly consisted of TiN, and TiO 2 and
only CoO/Cr 2 O 3 were identified on CoCrMo alloy. Besides, the surface roughness
of all the alloys increased and Ti samples exhibited the spike surface morphology.
Furthermore, the laser-treated CP-Ti and Ti64 alloy had lower water contact angle
values, while the contact angle value was remained similar for the CoCrMo alloy
compared to the untreated specimens. The S.aureus cell is hydrophobic therefore has
more interactions with the more hydrophobic surfaces, hence the S.aureus adhesion
with the laser-treated CoCrMo alloy was higher than the CP-Ti and Ti64 alloy. In
addition to the wettability, the presence of nitride/oxide surface layer on Ti alloy
and micro/nano features were also attributed to the resulting antibacterial properties. The femtosecond laser ablation treatment of CP-Ti (grade 2) produced a
micro/nanoscale quasi-periodic self-organized structures with hydrophobic nature
(166 ± 4°) compared to the untreated surface (73 ± 3°) which exhibited colonization of S.aureus bacteria, while the P.aeruginosa was not able to attach [61]. The
antibacterial activities of laser textured implant materials were improved and the
combination of surface roughness and composition were responsible for the better
properties.
LIPSS was produced on to Ti64 alloy and the laser wavelength, speed, and pulse
numbers altered the LIPSS average periods, and surface peak to valley distance.
The contact angle values measured using polar and non-polar liquids revealed
a hydrophilic character for the polished sample and UV-LIPSS and hydrophobic
behavior were observed for the GR-LIPSS specimens. The grooves in the nanometer
range LIPSS surface were smaller compared to the bacterial size, therefore, inhibited
the bacteria adhesion. On the other hand, the vertical growth of the bacteria leads
to the formation of shelters on the polished surface and helps the bacteria allocation
and proliferation. This phenomenon was strongly hindered by the nanostructured
surface, thus bacterial adhesion was hindered and resulted in anti-bacterial surfaces
[62].
LIPSS surfaces with different periodicities were fabricated on pure Ti grade 2
using a femtosecond laser and the rippled surfaces had sub-micron size surface
roughness and also, the LIPSS surface was hydrophobic (134 ± 14°) compared to
the control sample (84 ± 3°) [63]. The cells on the LIPSS were oriented perpendicular
S. Arthanari et al.
of 160°, 119°, and 140°, respectively. As the size of the E.coli (rod shape, ~ 0.5 μm
diameter and length ~ 2 μm) and S.aureus (spherical shape, ~ 0.5 μm diameter) was
varied, the bacterial adhesion behavior was also varied and the area occupied by the
E.coli and S.aureus are ~ 1 μm
2 /cell and 0.25 μm
2 /cell, respectively. Therefore, the
surfaces with features larger than the bacterial size (spikes) and similar to the bacterial
size (LIPSS and nano-pillars), thus affected bacterial contact and further adhesion.
The retention of the E.coli on the mirror polished and spikes surface was higher as
the surface dimension is larger than the cell size, however, S.aureus adhesion was
inhibited. Interestingly LIPSS and nano-pillars revealed 99.8% and 99.2% for the
E.coli and 84.7% and 79.9% for the S.aureus, respectively. The antibacterial activity
was attributed to both surface wettability and morphological change of the laser
textured specimens. A continuous-wave fiber laser-treated CP-Ti (grade 2), Ti64, and
CoCrMo alloys under the nitrogen atmosphere were tested for the S.aureus adhesion
[60]. The surface of the treated Ti samples was mainly consisted of TiN, and TiO 2 and
only CoO/Cr 2 O 3 were identified on CoCrMo alloy. Besides, the surface roughness
of all the alloys increased and Ti samples exhibited the spike surface morphology.
Furthermore, the laser-treated CP-Ti and Ti64 alloy had lower water contact angle
values, while the contact angle value was remained similar for the CoCrMo alloy
compared to the untreated specimens. The S.aureus cell is hydrophobic therefore has
more interactions with the more hydrophobic surfaces, hence the S.aureus adhesion
with the laser-treated CoCrMo alloy was higher than the CP-Ti and Ti64 alloy. In
addition to the wettability, the presence of nitride/oxide surface layer on Ti alloy
and micro/nano features were also attributed to the resulting antibacterial properties. The femtosecond laser ablation treatment of CP-Ti (grade 2) produced a
micro/nanoscale quasi-periodic self-organized structures with hydrophobic nature
(166 ± 4°) compared to the untreated surface (73 ± 3°) which exhibited colonization of S.aureus bacteria, while the P.aeruginosa was not able to attach [61]. The
antibacterial activities of laser textured implant materials were improved and the
combination of surface roughness and composition were responsible for the better
properties.
LIPSS was produced on to Ti64 alloy and the laser wavelength, speed, and pulse
numbers altered the LIPSS average periods, and surface peak to valley distance.
The contact angle values measured using polar and non-polar liquids revealed
a hydrophilic character for the polished sample and UV-LIPSS and hydrophobic
behavior were observed for the GR-LIPSS specimens. The grooves in the nanometer
range LIPSS surface were smaller compared to the bacterial size, therefore, inhibited
the bacteria adhesion. On the other hand, the vertical growth of the bacteria leads
to the formation of shelters on the polished surface and helps the bacteria allocation
and proliferation. This phenomenon was strongly hindered by the nanostructured
surface, thus bacterial adhesion was hindered and resulted in anti-bacterial surfaces
[62].
LIPSS surfaces with different periodicities were fabricated on pure Ti grade 2
using a femtosecond laser and the rippled surfaces had sub-micron size surface
roughness and also, the LIPSS surface was hydrophobic (134 ± 14°) compared to
the control sample (84 ± 3°) [63]. The cells on the LIPSS were oriented perpendicular