Imparting antimicrobial and anti-adhesive properties to polysulfone membranes through modification with silver nanoparticles and polyelectrolyte multilayers

The antimicrobial and bacterial anti-adhesive properties of polysulfone (PSU) membranes modified with silver nanoparticles (AgNPs) and polyelectrolyte multilayers (PEMs) composed of poly(allylamine hydrochloride) and poly(acrylic acid) were investigated. The membranes’ antimicrobial properties were evaluated using a colony forming unit (CFU) enumeration method, while the anti-adhesive properties of the membranes were examined using a direct microscopy observation membrane filtration system. The AgNP mass loading required for the inhibition of bacterial growth on the AgNP/PEM-modified membranes was significantly lower than the AgNP loadings reported in other studies for membranes with the nanoparticles dispersed within the membrane matrix. The immobilization of AgNPs on the membrane surface maximized the opportunities for bacteria-nanoparticle contact, which allowed for effective bacteria inactivation. Furthermore, in comparison to unmodified PSU membranes, the bacterial deposition kinetics on all the modified membranes were reduced by ca. 50% and the bacterial removal efficiencies were significantly increased from close to 0% to as high as over 90%. Three-cycle filtration and rinsing experiments were also performed to evaluate the effectiveness of the surface modification over an extended time period of use