| Given the growing demand for personal health care and the increasing ageing population, regenerative medicine has attracted more and more attention during the last few decades. Unfortunately, the healing site infection which caused by bacteria can eventually render the medical implants to fail. Bacterial adhesion to the implant in vivo has proven to be an initial and important step for the subsequent bacterial proliferation and infection. Thus, the implant surface, i.e. the biomaterial surface, may play a vital role in inhibiting biomaterial-centered infection if the surface possesses an anti-adhesive activity against bacteria. Many synergistic material parameters can affect the bacterial adhesion, including surface topography, chemistry, charge, and wettability. In the present study, we focus on the surface topographical effects on bacterial behaviors.;Here, we have employed photolithography to fabricate micro/nanoscale silicon pillar arrays (SiPA) with different feature sizes. The micro/nanoscale titanium dioxide pillar array (TiO2PA) was prepared by depositing a titanium thin film on the SiPA followed by thermal oxidation. The uniqueness of these pattern designs lies in introducing various pattern feature sizes and avoiding variations in the surface chemistry, charge and wettability to some extent for achieving a better understanding of how bacteria respond to different kinds of surface features. So far, Escherichia coli (E.coli) and Staphylococcus aureus (S.aureus) have been employed in this study since they have been extensively involved in studies of the topographical effects on bacterial behaviors.;The SiPA was cultured with bacteria (E.coli or S.aureus) for a set period of time. After comprehensive characterization and systematic analysis, we found that micro-pillars can manipulate bacterial (E.coli, S.aureus) adhesion because of physical confinement effects. Significant reduction in bacterial ( E.coli, S.aureus) adhesion, growth and proliferation can be achieved when the feature size of the pillar is decreased down to sub-micrometer level. However, micro-pillars do not have obvious influence on the viability of the bacteria (E.coli, S.aureus) within 24 h. Comparing the behaviors of E.coli and S.aureus on the patterned surfaces, it is hard to find any obvious difference. This may partly result from the small size difference between the E.coli and S.aureus. The whole set of experiments was repeated by changing the sample to TiO2PA. We confirmed that the topographical effects on bacterial (E.coli, S.aureus) behaviors do exist and are independent of the chemistry of the patterned surfaces.;From a theoretical point of view, the topographical effects on bacterial (E.coli) adhesion observed in this study show a certain degree of agreement with the Extended DLVO theory, but the theory cannot fully explain the experimental results. Furthermore, the 2D surface roughness parameters, like the Ra value, cannot be used to precisely characterize the 3D surface topography. Thus, we suggest that studies on the relationship between 2D surface roughness parameters and bacterial behaviors should no longer be conducted. |
