Invited: Biofilm Formation on Stainless Steel Surfaces Coated with Photocurable Resins Fabricated by VAT Polymerization

Photocurable polymer coatings were fabricated on AISI 304 stainless steel substrates using VAT polymerization with UV irradiation (approximately 400 nm). Acrylate-based coating layers with thicknesses of several tens of micrometers were formed on stainless steel plates (30 × 30 mm for static tests and 10 × 20 mm for flow tests, thickness 0.5 mm). Two types of UV-curable acrylate resins were investigated: one derived from hydrophilic monomers and the other from hydrophobic polymer components, resulting in coatings with different surface properties. Biofilm formation on the coated surfaces was evaluated using two experimental approaches. In the static immersion test, samples were exposed to a culture medium containing Staphylococcus epidermidis and Escherichia coli. In addition, a flow-type biofilm formation test was conducted using a biofilm acceleration apparatus developed by Yamamoto Plating Co., in which environmental soil bacteria were introduced under flowing conditions using tap water and nutrient medium. After incubation, the biofilm biomass was stained with crystal violet, extracted, and quantified by absorbance measurements. The experimental results were analyzed to examine the influence of coating hydrophilicity on biofilm formation behavior on stainless steel surfaces. This study provides insight into the relationship between surface chemistry of photocurable coatings fabricated by VAT polymerization and microbial adhesion characteristics.