Enhancing the anti-fouling and fouling removal properties of thin-film composite membranes through an intercalated functionalization method

Abstract

In this study, we propose an intercalated surface modification strategy that combines three important functionalities in thin-film composite (TFC) membranes: 1) resistance to the deposition of organic fouling, 2) anti-biofouling properties in static and cross-flow conditions, and 3) an improved self-cleaning property that reflects the membranes' ability to easily release attached bacteria cells. The membrane functionalization strategy consists of immobilizing a polydopamine (PDA) layer, followed by the intercalation of silver nanoparticles (AgNPs) and poly (sulfobetaine methacrylate) (PSBMA) zwitterionic brushes (PDA–Ag–PSBMA TFC). The presence of zwitterionic PSBMA brushes shields the membrane surface against the non-specific adsorption of fluorescent bovine serum albumin (BSA), demonstrating a superior anti-fouling property. Moreover, the PSBMA brushes impart the TFC membranes with an excellent ability to release attached cells under gentle agitation. AgNPs intercalated between PDA and PSBMA layers, on the other hand, enabled a prolonged anti-biofouling property by efficiently inactivating ∼90% of the attached Pseudomonas aeruginosa cells. Dynamic biofouling experiments under a cross-flow condition and confocal laser scanning microscopy (CLSM) imaging show reduced flux decline and inhibition of biofilm formation for PDA–Ag–PSBMA TFC membranes, respectively, confirming the effectiveness of our intercalated surface modification strategy for simultaneous control of organic fouling and biofouling.