Application of silver nanodots for potential use in antimicrobial packaging applications

Abstract A simple method to fabricate well-defined silver nanodots of different sizes using self-assembled polystyrene-b-poly(ethylene oxide) (PS-b-PEO) block copolymer was developed. The most well-defined nanodot patterns were observed using optimal concentrations of silver precursor (0.4, 0.6, and 1.2%) with average sizes of 10, 18, and 28 nm by different molecular weights of PS-b-PEO. Silver nanodot patterns were not observed at higher Ag precursor concentrations. In addition, after repeated depositions, the antimicrobial activity (AA) towards bacteria increased compared to well-defined nanodot arrangements. The AA of the silver nanodots was significantly affected by the concentration used independent of the particle size of the silver nanodots. Potentially, silver nanodots can be used as antimicrobial packaging application to preserve the quality of food products due to the data generated here demonstrated that these materials significantly delayed the growth of Pseudomonas fluorescens and Staphylococcus aureus . Industrial relevance Food wastage is a significant cost to industry and society as a whole and impacts all stages of the food distribution cycle from transport and storage to shelf life and end-consumer use. Antimicrobial packaging could significantly decrease product decomposition and add value for producers by preserving product shelf life. Metal-based nanoparticles (NPs) (especially Ag) have previously been identified as potential antimicrobials but their performance is dependent on factors such as size and shape, concentration, morphology, composition and crystallinity. Their use in packaging has been limited partly by issues such as size control, powder handling, surface attachment and application to polymer films which can be challenging. We developed a novel method for generating antimicrobial surfaces based around the self-assembly of a polystyrene-b-polyethylene (PS-b-PEO) block copolymer that is a simple, effective and efficient method for generating highly uniform size and shape defined NPs (as nanodots) on a surface in a well-defined arrangement without the need of expensive lithographic techniques. The developed silver nanodot surfaces exhibited good antimicrobial activity against Gram-positive and Gram-negative bacteria and potentially can be used in antimicrobial packaging applications.