Rice University: Ions, Not Particles, Make Silver Toxic to Bacteria
In this press release from Rice University, clinical researchers discuss the results of their new study titled “Negligible Particle-Specific Antibacterial Activity of Silver Nanoparticles,” which was published in the July 5, 2012 issue of the journal Nano Letters. In their study, the researchers demonstrate conclusively that silver ions, and not metallic silver particles (i.e., nanosilver) are what make silver toxic to bacteria.
The researchers found that the metallic (i.e., nanoparticle) form of silver is largely inert, and cannot kill pathogens except to the extent in sheds silver ions in the presence of pathogens. According to the study abstract, “For nearly a decade, researchers have debated the mechanisms by which AgNPs exert toxicity to bacteria and other organisms. The most elusive question has been whether the AgNPs exert direct ‘particle-specific’ effects beyond the known antimicrobial activity of released silver ions (Ag+). Here, we infer that Ag+ is the definitive molecular toxicant. We rule out direct particle-specific biological effects by showing the lack of toxicity of AgNPs when synthesized and tested under strictly anaerobic conditions that preclude Ag(0) oxidation and Ag+ release.”
