Biofilm-inactivating activity of silver nanoparticles: A comparison with silver ions

The antimicrobial activity of silver nanoparticles (AgNPs) against Pseudomonas aeruginosa PA01 planktonic and biofilm bacteria was examined; their activity was compared with that of silver ions. The inactivation of biofilms by AgNPs was greatly influenced by stirring, which caused an increased AgNP biosorption. Although the activity of AgNPs against planktonic cells was ca. 10% that of silver ions, their activity against biofilm cells was comparable to the silver ions’ activity at the same concentration after 90 min under stirring (ca. 3.5 log inactivation). AgNPs inactivated biofilms in a biosorption-dependent manner, whereas this was not the case for silver ions.