title: Antimicrobial silver: an unprecedented anion effect.
abstract: Silver is an indispensable metal but its use has to be minimised for sustainable growth. Much of the silver lost during use is unrecoverable; an example being its use as an antimicrobial agent, a property known since ages. While developing methods to create an affordable drinking water purifier especially for the developing world, we discovered that 50 parts per billion (ppb) of Ag(+) released continuously from silver nanoparticles confined in nanoscale cages is enough to cause antimicrobial activity in conditions of normal water. Here we show that the antibacterial and antiviral activities of Ag(+) can be enhanced ~1,000 fold, selectively, in presence of carbonate ions whose concentration was maintained below the drinking water norms. The protective layers of the organisms were affected during the carbonate-assisted antimicrobial activity. It is estimated that ~1,300 tons of silver can be saved annually using this new way to enhance its antimicrobial activity.
authors.affiliation: DST Unit of Nanoscience (DST UNS) and Thematic Unit of Excellence (TUE), Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India.
authors.forename: J R
authors.initials: JR
authors.lastname: Swathy
authors.affiliation: InnoNano Research, Chennai 600020, India.
authors.forename: M Udhaya
authors.initials: MU
authors.lastname: Sankar
authors.affiliation: InnoNano Research, Chennai 600020, India.
authors.forename: Amrita
authors.initials: A
authors.lastname: Chaudhary
authors.affiliation: DST Unit of Nanoscience (DST UNS) and Thematic Unit of Excellence (TUE), Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India.
authors.forename: Sahaja
authors.initials: S
authors.lastname: Aigal
authors.affiliation: InnoNano Research, Chennai 600020, India.
authors.lastname: Anshup
authors.affiliation: DST Unit of Nanoscience (DST UNS) and Thematic Unit of Excellence (TUE), Department of Chemistry, Indian Institute of Technology Madras, Chennai 600036, India.
authors.forename: T
authors.initials: T
authors.lastname: Pradeep
mesh_terms: D000838:Anions / Q000737:chemistry; D000890:Anti-Infective Agents / Q000737:chemistry* / Q000494:pharmacology; D002254:Carbonates / Q000737:chemistry*; D004926:Escherichia coli / Q000187:drug effects; D006863:Hydrogen-Ion Concentration; D053768:Metal Nanoparticles / Q000737:chemistry; D008856:Microscopy, Fluorescence; D010539:Permeability / Q000187:drug effects; D012834:Silver / Q000737:chemistry* / Q000494:pharmacology; D013211:Staphylococcus aureus / Q000187:drug effects; D014780:Viruses / Q000187:drug effects
chemical_list: D000838:Anions; D000890:Anti-Infective Agents; D002254:Carbonates; D012834:Silver