The effect of surface properties and application method on the retention of Pseudomonas aeruginosa on uncoated and titanium-coated stainless steel

Four commercially available stainless steel surfaces 316 2B, 304 2B, 304 coarse abraded and 304 fine polished with defined surface topographies (Ra 0.3–0.5 μm, Rz 2.5–3.8 μm) and comparable hydrophobicities (85.5±4.5°) were coated with 0.8 μm thick layers of titanium using magnetron sputtering. Coating the surfaces did not alter the surface Ra, Rz or surface hydrophobicity values. Substrata were immersed in a Pseudomonas aeruginosa cell suspension (retention assay), or were spray coated with the same suspension (spray assay). When cells were applied via retention assays, the pattern of surface topography affected the pattern of microbial retention on both uncoated and coated surfaces. After spraying application on 2B surfaces the same trends were noted. However, cells clusters were observed on coarse abraded and fine polished uncoated substrata. When substrata were coated with titanium, cells were more evenly spread across the surface and numbers were higher. This work illustrates that method of application and surface chemistry affects the overall distribution of cells, whereas surface topography influences the pattern of cell retention. This has implications in terms of material selection and cost for industries with an environment where corrosion of the stainless steel is likely to be minimal.