The
surface micro- and nanotopography of medical implant devices, together with the
surface architecture, are important factors controlling the extent of bacterial
attachment. This, in turn, impacts upon
the possibility of contracting an implant-borne infection. The attachment
behaviour of pathogenic bacteria such as Staphylococcus
aureus and Pseudomonas aeruginosa
on titanium surfaces has been investigated with a view to determining the
relationship between bacterial attachment and the surface roughness and
architecture. Our earlier studies have shown that S. aureus is a successful coloniser of surfaces possessing micro-
to nanoscale surface topography parameters, whilst P. aeruginosa was shown to poorly colonise nanoscopically smooth
surfaces. In this study, we demonstrate that the two bacterial strains studied
exhibited different attachment affinity for the two titanium substrates
investigated, each of which was nanoscopically smooth, but possessing different
surface nano-architecture. Transmission electron microscopy and atomic force
microscopy were used to assess nano-morphology of the titanium surfaces. The chemical
composition, crystallinity and hydrophobicity of the surfaces were examined
using X-ray photoelectron spectroscopy, X-ray diffractometry and contact angle
goniometry. It was found that titanium surfaces with sub-nanometrically sharp
nano-protrusions and a higher surface-aspect-ratio facilitated the increased
attachment of P. aeruginosa cells by approximately
five times. It is suggested that this type of the molecularly smooth surfaces
is consistent with the permitted degree of stretching of the rod-shape cell
membrane, which allows anchoring of the P.
aeruginosa cells to the surface of nano-smooth titanium.