title: Converting visible light into UVC: microbial inactivation by Pr(3+)-activated upconversion materials.
abstract: Herein we report the synthesis and properties of light-activated antimicrobial surfaces composed of lanthanide-doped upconversion luminescent nano- and microcrystalline Y(2)SiO(5). Unlike photocatalytic surfaces, which convert light energy into reactive chemical species, this work describes surfaces that inactivate microorganisms through purely optical mechanisms, wherein incident visible light is partially converted into germicidal UVC radiation. Upconversion phosphors utilizing a Pr(3+) activator ion were synthesized and their visible-to-ultraviolet conversion capabilities were confirmed via photoluminescence spectroscopy. Polycrystalline films were prepared on glass substrates, and the extent of surface microbial inactivation and biofilm inhibition under visible light excitation were investigated. Results show that, under normal visible fluorescent lamp exposure, a sufficient amount of UVC radiation was emitted to inhibit Pseudomonas aeruginosa biofilm formation and to inactivate Bacillus subtilis spores on the dry surfaces. This new application of upconversion luminescence shows for the first time its ability to deter microbial contamination and could potentially lead to new material strategies for disinfection of surfaces and water.
authors.affiliation: School of Civil and Environmental Engineering, Georgia Institute of Technology , 200 Bobby Dodd Way, Atlanta, Georgia 30332-0373, United States.
authors.forename: Ezra L
authors.initials: EL
authors.lastname: Cates
authors.forename: Min
authors.initials: M
authors.lastname: Cho
authors.forename: Jae-Hong
authors.initials: JH
authors.lastname: Kim
mesh_terms: D001412:Bacillus subtilis / Q000502:physiology / Q000528:radiation effects*; D018441:Biofilms / Q000528:radiation effects; D022082:Cellular Structures / Q000187:drug effects; D004203:Disinfection / Q000379:methods*; D008027:Light; D050296:Microbial Viability / Q000187:drug effects*; D055668:Photochemical Processes; D011550:Pseudomonas aeruginosa / Q000502:physiology / Q000528:radiation effects*; D013171:Spores, Bacterial / Q000187:drug effects; D014466:Ultraviolet Rays; D018508:Water Purification / Q000379:methods