Effect of silver concentration and chemical transformations on release and antibacterial efficacy in silver-containing textiles

Abstract

Silver-enabled fabrics may be transformed during use in ways that may affect their release characteristics and antibacterial efficacy. Here, we assess how chemical transformations of silver in fabrics treated with Ag nanoparticles or AgCl particles, or containing interwoven Ag0 fibers affect silver leaching and their antibacterial efficacy under different use and end-of-life scenarios. Fabrics were exposed to artificial sweat (use phase) or artificial landfill leachate (sodium chloride, sodium sulfide, or acetic acid; end of life phase). Chemical transformations induced by exposure to sodium chloride, sodium sulfide and acetic acid result in variations in Ag release and corresponding changes in bactericidal properties of the Ag-treated textiles. Exposure to solutions containing chloride ions (sodium chloride and artificial sweat) generally increased leaching compared to deionized water. Conversely, exposure to sodium sulfide and acetic acid solutions decreased Ag release. Exposure to artificial sweat did not affect antibacterial efficacy for fabrics with greater than ~10 μg Ag (g fabric)−1. Sulfide solution exposure decreased antibacterial performance for all but the 500 μg Ag (g fabric)−1. The lower efficacy was consistent with chemical transformation of elemental Ag to AgCl/Ag0 or Ag2S, respectively for chloride and sulfide exposure. AgCl-coated fabrics were more resilient to chemical attack than Ag0-enabled fabrics. These results indicate that fabrics with as low as ~10 μg Ag (g fabric)−1 can maintain high antibacterial efficacy under normal use phase conditions, but below this concentration efficacy significantly decreases. Taken together, the data permit a comparison of the benefits (antimicrobial efficacy) in the context of the impacts (silver release) and inform selection and design of materials and loadings that give the best overall lifecycle benefit.