Bacteria mostly prefer to live as biofilms on surfaces rather than in flowing environments. However, biofilms are mostly unwanted by humans and preventing possibilities besides biocides and antibiotics are urgently needed. One strategy is to prevent the bacteria directly from attaching to the substrate. This study aims to investigate the effect of nano- and microstructures on bacterial attachment and pursues two approaches whether such surfaces reduce bacterial attachment under flow conditions. The first approach involves ZnO nanorods to design surfaces with varying topographies in the nano- and micrometer range, while the second uses 3D printed microstructures to induce microflows that repel bacteria from the surface. The tailored substrates were integrated into a specially developed flow chamber and exposed to a flowing suspension of P. fluorescens under in-situ conditions. Additionally, the attached bacteria were subjected to higher shear forces by increased flow velocities. For evaluation, the attached bacteria were imaged using fluorescence microscopy and automated counted on a single-cell level. The cell counts were compared between different substrates and a control surface to assess the effectiveness of the surfaces in preventing bacterial attachment. Lower cell numbers indicated a surface that better prevented bacterial attachment. However, it was found that none of the investigated surfaces reduced the attachment of P. fluorescens. These findings and additionally made observations have the potential to alter the current perspective of the believed capability of nano and microstructures for preventing microbial attachment. Remarkably, it was found that although accompanying computational fluid dynamic simulations predicted uniform flows in the channels, anomalies in the flows occurred, resulting in uneven distribution of the bacteria. Furthermore, P. fluorescens revealed the ability to attach to any surface studied and rapidly establish irreversible attachment there. Thus, this study also suggests using those microorganism types that perform best in attachment for benchmarking surfaces that are intended to have a bacteria-repellent effect in the future. During the project, a method for a lipopolysaccharide encapsulated polystyrene (LPS-PS) microparticle system was developed as a further approach. The easy-to-use method was developed to mimic bacteria for attachment studies. A variety of analytical techniques were used to detect the LPS on the polystyrene microparticles. Among others, a procedure for labeling the particles for fluorescence microscopy is presented. The data from the analyses offers a reference for future applications of the LPS-PS microparticles, whose use goes far beyond bacterial attachment studies; they are attractive for vaccine research and serological tests.
