Enhancement of Antibacterial Performance of Silver Nanowire Transparent Film by Post-Heat Treatment

Silver nanomaterials (AgNMs) have been applied as antibacterial agents to combat bacterial infections that can cause disease and death. The antibacterial activity of AgNMs can be improved by increasing the specific surface area, so significant efforts have been devoted to developing various bottom-up synthesis methods to control the size and shape of the particles. Herein, we report on a facile heat-treatment method that can improve the antibacterial activity of transparent silver nanowire (AgNW) films in a size-controllable, top-down manner. AgNW films were fabricated via spin-coating and were then heated at different temperatures (230 and 280 degrees C) for 30 min. The morphology and the degree of oxidation of the as-fabricated AgNW film were remarkably sensitive to the heat-treatment temperature, while the transparency was insensitive. As the heat-treatment temperature increased, the AgNWs spontaneously broke into more discrete wires and droplets, and oxidation proceeded faster. The increase in the heat-treatment temperature further increased the antibacterial activity of the AgNW film, and the heat treatment at 280 degrees C improved the antibacterial activity from 31.7% to 94.7% for Staphylococcus aureus, and from 57.0% to 98.7% for Escherichia coli. Following commonly accepted antibacterial mechanisms of AgNMs, we present a correlation between the antibacterial activity and surface observations of the AgNW film.