Drying Paint Delivers A Silver Bullet

About the simplest method one could imagine for endowing oil-based house paint with antibacterial properties-adding some reagents and watching the paint dry-has been developed by researchers at the City College of New York and Rice University (Nat. Mater., DOI: 10.1038/nmat2099). Unsaturated hydrocarbons in vegetable oil paints dry by an autooxidative, free-radical cross-linking reaction. CCNY's George John and coworkers conceived of chemistry that rides piggyback on free radicals. They add a silver salt to an alkyd paint, and as the painted surface dries, free radicals reduce the silver ions, forming antibacterial silver nanoparticles. In this green chemistry technique, "we are using a natural process to make nanoparticles in situ, without any additional solvents or energy," John notes. The coatings show antibacterial activity toward Escherichia coli and Staphylococcus aureus bacteria. Although antibacterial silver nanoparticle paints are commercially available, the new approach "uses natural materials and is quite simple," comments Michigan State University chemist Merlin L. Bruening.