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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