Strategies to Prevent Bacterial Adhesion on Biomaterials - Biomimetics: Advancing Nanobiomaterials and Tissue Engineering - page 170

considered to be responsible for reducing the bacterial attachment on the
surface [51].
The bacterial adhesion depends on shear stresses [52]. In a study, it is
reported that shear stress of 0.5 pN mm −2 increases E. coli accumulation
and a lack of shear might cause bacterial detachment [53]. Bacterial adhe-
sion is also very sensitive to the antibiotics and, hence, the bacterial sus-
ceptibility and antibiotic concentration will infl uence the adhesion [54]. In
most of the studies, it is reported that the antibiotic treatment is less effec-
tive for adhered bacterial cells than nonadherent cells, because bacterial
cells alter their metabolism and formulate resistance towards unfavorable
conditions [55].

7.2.4.1.2 Surface Chemical Composition
The surface chemical composition plays a very important role in the bacte-
rial adhesion and proliferation process. Surface charge of the biomaterial
depends on the functional group. And this generated charge infl uences
hydrophobicity of materials. Therefore, chemical bonds affect the bacterial
adhesion on substrate surface. Surface modifi cation with different types
of materials, like ZnO and Ag, reduces the bacterial adhesion, and surface
modifi cation with bioactive material, like hydroxyapatite, enhances the
bacterial adhesion [56].

7.2.4.1.3 Surface Roughness
Bacteria prefer to adhere and proliferate on irregular biomaterial surfaces
rather than ultra smooth surface. More surface area on the roughened

surfaces may attract the cells for colonization. For example, polymeth-
ylmethaacrylate amplify bacterial adhesion when surface roughness is
slightly increased [57].

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7.2.4.1.4 Surface Confi guration
Bacterial infection is reported to be more prominent in porous implants
than in dense scaffold. Therefore it can be concluded that porous surface
promotes bacteria adhesion. Pores have higher surface area than the fl at
surface, and bacteria prefer to enlarge their contact with surface. Moreover,
bacteria move towards grooves and adhere to increase their contact area
with surface, but if pore sizes are much bigger than the cell size the bacte-
ria may drift toward fl at surface rather than irregular surface [58].

7.2.4.1.5 Bacterial Characteristics
Bacterial adhesion not only depends on substrate characteristics and
environmental conditions, but is greatly infl uenced by their own physi-
cochemical characteristics. Some important bacterial characteristics are
discussed below.
Bacterial hydrophobicity: It is well known that bacteria with hydropho-
bic surface characteristics prefer to adhere on hydrophobic material sur-
faces. Shear stress greatly infl uences the bacterial adhesion on surface [9].