Abstract: Bacterial adhesion is a critical process in many fields, such as implant infections, microbiologically influenced corrosion and bioelectricity generation in microbial fuel cells. During bacterial adhesion, the contact area between the attached bacteria and the patterned surface plays an important role. In this study, different surface topographies and treatments were employed to simulate three circumstances with different contact areas. A nanostripe structure with a period of 576.9 nm and a height of 203.5 nm was fabricated on pure titanium by femtosecond laser ablation. Bacteria in liquid attached to the peaks of the nanostripe structure and were stretched on the two adjacent nanostripes. Compared with the polished surface, the contact area between bacteria and the nanostripe surface was reduced to 50 %, resulting in a reduction (about 50 %) in the coverage rate of attached bacteria. In addition, the nanostripe surface was a hydrophobic surface with a water contact angle (WCA) of 112.1°, and the surface potential of the nanostripe surface was higher than that of the polished surface. However, the surface potential and wettability of the nanostripe surface played a minor role in the bacterial adhesion due to the reduced contact area. Upon drying, the attached bacteria on the nanostripe surface sank into the valley region and the contact area was about 40 % larger than that on the polished surface. The lateral strength of bacterial adhesion on nanostripe surfaces was higher than that on polished surfaces, due to the larger contact area. Upon applying a lateral force of 10.0 nN, the percentage of bacteria remaining on the nanostripe surface (31.1 %) was higher than that on the polished surface (11.9 %). Hence, the bacterial adhesion on the nanopatterned surface was mainly determined by the contact area. The in-depth exploration of the relation between bacterial adhesion on the nanopatterned surface and the contact area enables the rational surface designs of biomaterials to regulate bacterial adhesion.

Key words: Bacterial adhesion, Contact area, Nanopatterned surface, Atomic force microscope