Physicochemical Properties Modulate Anti-adhesion of Pseudomonas aeruginosa to Block Copolymer Films: Impact of Surface Skewness, Kurtosis, and Wettability

This study explores the bacterial anti-adhesion characteristics of poly(styrene-b-methyl methacrylate) (PS-b-PMMA) di-block copolymer films against the pathogen Pseudomonas aeruginosa, with the goal of identifying evaporative processing conditions and nanoscale topographic features that modulate bacterial adhesion independent of surface wettability. PS-b-PMMA films with varying PMMA chain lengths were prepared through evaporative drying under different relative humidity conditions (RH). The resulting films were characterized using atomic force microscopy (AFM), water contact angle (WCA) measurements, and fluorescence imaging to determine the relationship between physiochemical properties (surface roughness and wettability) and bacterial adhesion. WCA results showed that film hydrophilicity varied systematically with increasing PMMA block length, and bacterial attachment generally decreased with increasing hydrophilicity. The relative distribution of peaks and valleys described by skewness (Rsk), and the surface feature sharpness, quantified by kurtosis (Rku) were strongly associated with bacterial anti-adhesion. Specially, bacterial count and bacterial coverage area % decreased with increasing Rku and Rsk. By contrast, bacterial count and bacterial coverage area % showed weak correlation with average roughness (Ra), possibly due to the limited range of average roughness of this film series. These findings highlight strategies to control bacterial adhesion through evaporative film formation and nanoscale texturing, particularly where there are constraints on material and surface wettability characteristics.