Biofunctionalized nanofibrous membranes as super separators of protein and enzyme from water

•A nanofibrous membrane is bio(protein) functionalized for water filtration.•The membrane is able to separate even trace amounts of biomolecules from water.•Despite the macroporosity of the membrane, the rejection efficiency is ∼90%.•The conformational change of the protein upon wetting maximizes the filterability.•Besides the optimum selectivity, the membranes are highly wettable thereby water permeable.

Here, we report development of a novel biofunctionalized nanofibrous membrane which, despite its macroporous structure, is able to separate even trace amounts (as low as 2 mg/L) of biomolecules such as protein and enzyme from water with an optimum efficiency of ∼90%. Such an extraordinary protein selectivity at this level of pollutant concentration for a nanofibrous membrane has never been reported. In the current study, poly(acrylonitrile-co-glycidyl methacrylate) (PANGMA) electrospun nanofibers are functionalized by a bovine serum albumin (BSA) protein. This membrane is extraordinarily successful in removal of BSA protein and Candida antarctica Lipase B (Cal-B) enzyme from a water based solution. Despite a negligible non-specific adsorption of both BSA and Cal-B to the PANGMA nanofibrous membrane (8%), the separation efficiency of the biofunctionalized membrane for BSA and Cal-B reaches to 88% and 81%, respectively. The optimum separation efficiency at a trace amount of protein models is due to the water-induced conformational change of the biofunctional agent. The conformational change not only exposes more functional groups available to catch the biomolecules but also leads to swelling of the nanofibers thereby a higher steric hindrance for the solutes. Besides the optimum selectivity, the biofunctionalized membranes are highly wettable thereby highly water permeable.

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