Here is an excellent study from 2017 with an overview w/ references of the effectiveness of Silver Nanoparticles as a broad spectrum antimicrobial. It's a great introduction to the science that began in 1884.
"In 1884, German obstetrician Crede introduced 1% silver nitrate (AgNO3) as an eye solution for avoidance of gonococ-cal ophthalmia neonatorum.... Nano-silver has been used in the treatment of wounds, burns, in water disinfecting systems, dental materials, and as antibacterials, antivirals, and anti-cancerous agents... a comparative study of AgNPs, AgNO3, and silver chloride (AgCl) found that AgNPs have the highest antibacterial properties..."
