Characterization of a Model Bioreactive Membrane for the Simultaneous Separation and Hydrolysis of Lipopolysaccharides

Abstract

The design of functionalized selective layers to develop novel membranes is essential to provide potential solutions that meet the continuously growing demand of providing safe water. Herein, we present the interfacial response of an enzymatic thin-film composite (E-TFC) membrane displaying dual functionality and fabricated as a proof-of-concept for both efficient lipopolysaccharide (LPS) separation and ester bond hydrolysis. The enzymatic membrane model was constructed by employing lipase b from Candida antarctica (CALB) covalently coupled via chemically activated bisepoxide groups onto the surface of the di-block copolymer polystyrene-b-poly(4-vinyl pyridine) (PS-b-P4VP) layer. Our results show a complete rejection of size-excluded LPS molecules when using the fabricated E-TFC membrane in a forward osmosis (FO) application. Moreover, the immobilized enzyme was able to retain 97% of its enzymatic activity when using 4-nitrophenyl acetate (pNPA) and up to 74% to liberate free fatty acids from LPS molecules within the feed side of the FO system. This work provides fundamental insights into new emerging functional biomaterials that find applications in hybrid catalytic filtration processes that also selectively remove LPS molecules from water sources.