Antifouling membranes employing a 2D planar nanobiocatalyst of crosslinked glucose oxidase aggregates wrapping extra-large graphene oxide

This paper presents highly effective antimicrobial surfaces employing a 2D structured nanobiocatalyst composed of graphene oxide (GO) and glucose oxidase (GOD). Enzyme molecules are immobilized onto extra-large GO pieces with a plane dimension of approximately 100 μm via an enzyme adsorption, precipitation, and crosslinking (EAPC) approach. This enables the effective wrapping of extra-large GO pieces by a matrix of crosslinked enzyme aggregates, which improves the enzyme loading. Consequently, the measured GOD activities of the EAPC sample via 50% (w/v) ammonium sulfate precipitation are 4,940 and 3,820 times higher than those of the control samples, i.e, the enzyme adsorption (EA) and enzyme adsorption/crosslinking (EAC) samples, respectively. The preservation of the planar GO geometry with an extra-large surface also allows the effective binding of EAPC onto a commercial membrane filter via a polydopamine coating, thus yielding a biocatalytic EAPC membrane. Compared to the commercial membrane with no bound EAPC, the in situ generation of H₂O₂ via the EAPC-catalyzed oxidation of glucose on the membrane surface demonstrated enhanced filterability against a mixed bacterial population of activated sludge obtained from a municipal sewage plant as well as two model bacteria: gram-negative Pseudomonas aeruginosa and gram-positive Staphylococcus aureus. The bacterial decontamination of the EAPC-bound membrane surface can also be activated on demand by simply adding glucose to the bulk solution. This newly proposed mechanism of antifouling surfaces employing a localized nanobiocatalytic conversion of nontoxic glucose to bactericidal H₂O₂ can provide insights for biofouling control via a highly effective and environment-friendly approach.