Antimicrobial Thin-Film Composite Membranes with Chemically Decorated Ultrasmall Silver Nanoclusters

Developing bactericidal membranes is of interest to the membrane industry in seawater desalination and other water purification processes. The pivotal step for the fabrication of a high performance bactericidal membrane is the delicate design of bactericidal materials, which should feature high efficiency, long lifetime, and low cost. Ultrasmall silver nanoclusters (AgNCs, less than 2 nm, which could maximize the use of active Ag species) have recently emerged as a promising class of inorganic antimicrobial agents. Leveraging on the unique properties of AgNCs, here, we developed an efficient protocol to integrate AgNCs into polymeric membranes (e.g., forward osmosis (FO) membranes), leading to the formation of a high performance antimicrobial thin-film composite membrane. In particular, the AgNC-modified membranes can effectively inhibit the growth of Escherichia coli, without obvious activity decay over a test period of 1 month. In addition, the strong thiolate-metal interaction in thiolate-protected AgNCs offers a sustainable and controllable dissolution of silver ions, acting as active antimicrobial species. More interestingly, the AgNC-decorated membranes show improved FO performance as compared to the pristine membranes. The delicate design of AgNCs and the fabrication protocol developed in this study might provide a promising platform to fabricate antimicrobial membranes for various industrial applications.