research in 2018 into the treatment of central nervous system infections caused by free-living amoebae such as "naegleria fowleri" and "acanthamoeba castellanii", tested the effectiveness of existing drugs as well as the effectiveness of the same drugs when they were conjugated with silver nanoparticles. in vitro tests demonstrated more potent amoebicidal effects for the drugs when conjugated with silver nanoparticles as compared to the same drugs when used alone. they also found that conjugating the drugs with silver nanoparticles enhanced their anti-acanthamoebic activity.