Stable and efficient loading of silver nanoparticles in spherical polyelectrolyte brushes and the antibacterial effects.

A more efficient and convenient strategy was demonstrated to immobilize silver nanoparticles (NPs) with a crystalline structure into the spherical polyelectrolyte brushes (SPB) as an antibacterial material. The SPB used for surface coating (Ag immobilized PVK-PAA SPB) consists of a poly(N-vinylcarbazole) (PVK) core and poly(acrylic acid) (PAA) chain layers which are anchored onto the surface of PVK core at one end. Well-dispersed silver nanoparticles (diameter∼3.5 nm) then formed and were electrostatically confined in the brush layer. Ag content is controlled by a repeated loading process. Thin film coatings were then constructed by layer-by-layer depositions of positive charged poly(diallyldimethylammonium chloride) (PDDA) and SPB. The multilayer composites display excellent stability as well as antibacterial performance but not for simple PVK-PAA coated surface. The results show that almost complete bacteria growth including both dispersed bacterial cells and biofilms was inhibited over a period of 24 h. This approach opens a novel strategy for stable and efficient immobilization of Ag NPs in fabrication of antibacterial materials.