Spacing-Dependent Antimicrobial Efficacy of Immobilized Silver Nanoparticles

Silver nanoparticles (Ag NPs) with a similar mean particle diameter (similar to 5.0 nm) but distinguished dispersion densities were in situ fabricated and immobilized on plasma-sprayed titanium oxide coatings by a silver plasma immersion ion implantation process (Ag Pill). Experiments and theoretical predictions demonstrated that the efficacy of these Ag NPs against bacteria relies on their electron storage capability, which is the interparticle distance associated in the dark, and it is inversely dose-dependent. A particle population with a relatively large spacing distance is superior in concentrating the electrons extruded by bacterial cells, activating oxidative reactions, and disrupting the bacterial cells. The finding opens up a new window leading to active design and control of the interactions between materials and biological systems.