THESIS
2013
xviii, 92 pages : illustrations ; 30 cm
Abstract
The adhesion of bacteria to medical implants forming biofilms might lead to
healthcare-associated infections. Initial bacterial adhesion is mediated by material
surface properties. Therefore, control of bacterial adhesion to material surfaces is
important for reducing infection. Numerous researches have been devoted to the
chemical and physical modification of biomaterial surfaces to control initial bacterial
adhesion. However, the successful design of biomaterials for the treatment of infections
remains a challenge.
Surface topographic patterns of micro- or nano-scale have been effective to manipulate
behavior of different types of cells. Previously, the bacterial behavior on the
micro-pillar patterned surfaces has been studied in our group and confirmed that the
micro-pilla...[
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The adhesion of bacteria to medical implants forming biofilms might lead to
healthcare-associated infections. Initial bacterial adhesion is mediated by material
surface properties. Therefore, control of bacterial adhesion to material surfaces is
important for reducing infection. Numerous researches have been devoted to the
chemical and physical modification of biomaterial surfaces to control initial bacterial
adhesion. However, the successful design of biomaterials for the treatment of infections
remains a challenge.
Surface topographic patterns of micro- or nano-scale have been effective to manipulate
behavior of different types of cells. Previously, the bacterial behavior on the
micro-pillar patterned surfaces has been studied in our group and confirmed that the
micro-pillar pattern do have effects on the bacterial behavior. Now in this study we
further fabricated a honeycomb pattern which provided a reduced continuous surface
area compared with micro-pillar pattern. The honeycomb patterns on silicon substrate
with characteristic dimensions varied from 0.5 μm to 10 μm were fabricated. Two
typical bacteria with distinctive shapes (E.coli and S.aureus) were used as study models.
After culturing the samples with bacteria, the effects of honeycomb patterns on the
bacterial adhesion, growth, proliferation and viability were investigated.
Experimental results show that the honeycomb topography with specific feature size
around 1 μm can significantly reduce bacterial adhesion. Furthermore, the honeycomb
patterns can inhibit bacterial growth and change the direction of growth when the
bacterial is confined into a well. These influences may result from the physical
confinement effect on bacteria. By comparing Sample_UP vs. Sample_DOWN, the adherent bacterial is much less on Sample_DOWN, but the trends of bacterial
adhesion are the same and irrespective of the gravity of bacteria. In comparison with
bacterial responses to pillar patterns, we found that topographic patterns with
dimensions approaching to bacterial size can provide stronger physical confinement
effect than others. However, the viability of the bacteria does not obviously influenced
by the pillar and honeycomb topography within 24h.
This study is expected to contribute to better understanding of topographic effects on
bacterial behavior and healthcare-associated infections on biomaterials.
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