Biomedical Engineering Reference
In-Depth Information
These studies show that the nanostructuration of metal implants
may improve the adhesion and differentiation of osteoblastic
cells. However, further studies are necessary to corroborate these
preliminary results
in vivo
.
Independently studies have shown that by varying the surface
roughness of a biomaterial, bacteria adhesion decreases [25]. Simple
means for the reduction of bacteria on and subsequent infection of
titanium using nanometer sized Ti surface features was explored for
medical applications by Webster and coworkers [108].
This study found that compared to conventional (nano-smooth)
Ti, the nanorough Ti surfaces produced by electron beam evaporation
decreased the adherence of all of the aforementioned bacteria the
most. The conventional and nanorough Ti surfaces were found to
have crystalline TiO
2
while the nanotubular and nanotextured Ti
surfaces were found to be amorphous. The surface chemistries were
similar for the conventional and nanorough Ti while the anodized
Ti surfaces contained luorine. Therefore, the results of this study
in vitro
demonstrated that certain nanometer sized Ti topographies
may be useful for reducing bacteria adhesion while promoting bone
tissue formation and, thus, should be further studied for improving
the eficacy of Ti-based implants.
The unmodiied titanium (Ti) possessed micron rough surface
features as displayed under SEM (Fig. 12.4(a)). After electron beam
evaporation, the Ti substrates possessed a high degree of nanometer
surface features, thus, creating a more nanometer rough surface
topography (Fig. 12.4(b)). Completion of anodization for 1 min
in 0.5% hydroluoric acid (HF) at 20 V resulted in a Ti substrate
containing nanotextured surface features (Fig. 12.4(c)). Increasing
the anodization time (10 min) and concentration of HF (1.5%)
resulted in a Ti surface that contained nanotubular like structures
with an inner diameter from 60 to 70 nm, as estimated from the SEM
images (Fig. 12.4(d)).
Results from this study indicated that the prepared nanorough
Ti surfaces are the best surfaces for inhibiting bacterial adhesion.
Compared to conventional surfaces, nanostructured materials have
excellent biocompatibility properties due to enhanced protein
interaction (including adsorption and conformation) resulting in
improved cellular adhesion and tissue growth [64, 136, 146]. It has
been demonstrated that there is a linear relationship between nano-
roughness, surface energy, and protein adsorption. More speciically,
