With the advent of Nanotechnology, silver nanoparticles increasingly are being used in coatings, especially in medical device applications, to capitalize on their antimicrobial properties. The increased antimicrobial efficacy of nanoparticulate silver systems relative to their bulk counterparts may be attributed to an increased silver ion (Ag+) solubility, and hence availability, that arises due to large curvatures of the small nanometer-sized particles. However, a change of the material upon which the antimicrobial nanoparticulate silver is deposited (herein called "substrate") may affect the availability of Ag+ ions and the intended efficacy of the device. We utilize both theory and experiment to determine the effect of substrate on ion release from silver particles in electrochemical environments and find that substrate surface change, chemical reactivity or affinity of the surface for Ag+ ions, and hence antimicrobial efficacy. It is also observed that with time of exposure to DI water, Ag+ ion release increases to a maximum value at 5 minutes before decreasing to undetectable levels, which is attributed to coarsening of the nanoparticles, which subsequently reduces the solubility and availability of Ag+ ions. This coarsening phenomenon is also predicted by the theoretical considerations and has been confirmed experimentally by TEM.
Citation: Nano Letters
Pub Type: Journals
Nanoparticles, Antimicrobial, Silver Ion, Phase field, Electrochemistry, Surface charge