Trypsin-enabled construction of anti-fouling and self-cleaning polyethersulfone membrane

Constructing anti-fouling and self-cleaning membrane surfaces based on covalent attachment of trypsin on poly(methacrylic acid)-graft-polyethersulfone (PMAA-g-PES) membrane was reported. The carboxylic acid groups enriched on asymmetric PMAA-g-PES membrane surface were activated with 1-ethyl-(3-3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS) and employed as chemical anchors for the conjugation with amino groups of trypsin. Activity assays showed that such chemically immobilized trypsin was much more active and stable than that of the physically adsorbed counterpart. Trypsin covalently attached on membrane surface could substantially resist protein fouling in dynamic flow process. The considerable enhancement of protein solution permeation flux was observed as a consequence of rapid enzymatic degradation of protein deposited onto membrane surface. The permeation flux of the membrane could be recovered upon simple hydraulic flush after protein filtration, suggesting superior self-cleaning property. After multi-cycle BSA filtration over 15-day period, the active self-cleaning membrane maintained more than 95.0% of its initial flux.