Bacterial Adhesion and Interaction with Biomaterial Surfaces - Biointerfaces: Where Material Meets Biology - page 388

bacterial adhesion and controlling the bacterial adhesion to biomaterials.
However, microbial infection still remains a serious problem for long term
use of implanted medical devices. This is partially because bacterial ad-
hesion is a very complicated process that is affected by many factors such
as material surfaces and environments. The other reason is that the
bacterial surface compositions/structures and their functional roles in bac-
terial adhesion and biofilm formation are still not clear. For example, future
studies may need to address the functions of PIA, AaP, Bhp or Embp in
S. epidermidis adhesion and biofilm formation, as well as their responses to
antibiotics. 26
Understanding the molecular interaction at the material-bacteria inter-
face is fundamental to controlling bacterial adhesion to biomaterial sur-
faces. The major point in bacterial adhesion appears to be the role of
proteins adsorbed on surfaces. The conformational structure and biological
function of proteins adsorbed are affected by material surface properties
(e.g., surface chemistry, nanotopography) and they in turn influence bac-
terial adhesion. Future research in this field will need to better address the
correlation of nanoscale surface properties and protein conformation, and
correlate to the biological response bacterial adhesion. Certainly, this will
rely on a better analysis and understanding of the influence of nanoscale
surface properties on quantity and conformational structure of proteins
adsorbed, and will require a development of new techniques or an
improvement of the existing techniques to obtain this information.
One representative example in this field is the increased use of novel,
high-resolution AFM techniques for imaging surfaces and mapping the
interactions of material and bacteria. Furthermore, combinations of AFM
with other characterization methods such as confocal microscopy and
Raman spectroscopy 168,193,194 greatly expanded the amount and types of data
one can obtain simultaneously, and greatly help to know the molecular
mechanisms of bacterial responses to adhering surfaces.

d n 3 r 4 n g | 3

.

A Appendix: Methods

A.1 Typical Parameters for AFM Imaging of Microphase
Separation Structure in Polyurethane Biomaterial
Surfaces in Solution
Probe:Si 3 N 4 , spring constant ¼ 0.06 to 0.58 N m 1 , probe curvature
radius o 10 nm
Mode: tapping
Scan size: 500 nm 500 nm or 1 mm 1 mm
Resolution: 512 512 or 256 256
Scan rate: 0.5 to 1 Hz
Moderate tapping force: r sp B 0.75 (set point amplitude/free amplitude

of oscillation)
Data type: height, phase, amplitude