Influence of sub-micron surface patterns on the deposition of model proteins during active filtration

In this study, the effects of sub-micron surface patterns on the fouling of a model protein solution (bovine serum albumin (BSA)), was investigated during active filtration and simple adsorption conditions. Surface patterns were created directly onto a commercial polyethersulfone ultrafiltration membrane using nanoimprint lithography, which resulted in a moderately reduced molecular mass cut-off (MWCO) but similar permeance as its non-imprinted counterpart as well as significantly improved resistance to BSA fouling. Staged filtration experiments, with backwash cleaning, revealed that the permeate flux of the imprinted membrane was considerably higher than that of the non-imprinted membrane, consistent with UV–vis measurements showing less protein deposition on the imprinted membranes. This improvement in anti-fouling characteristics for the imprinted membrane was universally observed for varying feed-solution chemistry including changes in both pH and ionic strength. From controlled protein-adsorption experiments under non-filtration conditions, it appears that the observed decrease in protein adsorption on the imprinted membranes is likely associated with altered hydrodynamics due to the presence of the sub-micron patterns.