Nanopatterning Reduces Bacteria Fouling in Ultrafiltration

This contribution describes a method to reduce bacteria fouling on ultrafiltration membranes by applying nanoscale line-and-groove patterns on the surface of membranes. Nanoimprint lithography was used to pattern the polysulfone membrane surfaces with a peak height of 66.2 nm and a period of 594.0 nm. Surface characterization using scanning electron microscopy and atomic force microscopy confirmed that patterning was successful over the entire stamped area of the membrane. Water permeance tests determined that the permeance decreased by 36% upon patterning. Static batch experiments that explored the attachment of Escherichia coli K12 cells to the membranes demonstrated that the patterned membranes had a 60% lower attachment of microbes than the nonpatterned membranes. Dynamic bacteria fouling experiments using E. coli cells showed that the patterned membranes had a higher flux recovery ratio (88%) compared to the nonpatterned membranes (70%). On the basis of these studies, we suggest that patterning membranes can reduce the initial attachments of microbial cells and that different pattern sizes and shapes should be investigated to gain a fundamental understanding of their influence on bacteria fouling.