title: Biomagnification of cadmium selenide quantum dots in a simple experimental microbial food chain.
abstract: Previous studies have shown that engineered nanomaterials can be transferred from prey to predator, but the ecological impacts of this are mostly unknown. In particular, it is not known if these materials can be biomagnified-a process in which higher concentrations of materials accumulate in organisms higher up in the food chain. Here, we show that bare CdSe quantum dots that have accumulated in Pseudomonas aeruginosa bacteria can be transferred to and biomagnified in the Tetrahymena thermophila protozoa that prey on the bacteria. Cadmium concentrations in the protozoa predator were approximately five times higher than their bacterial prey. Quantum-dot-treated bacteria were differentially toxic to the protozoa, in that they inhibited their own digestion in the protozoan food vacuoles. Because the protozoa did not lyse, largely intact quantum dots remain available to higher trophic levels. The observed biomagnification from bacterial prey is significant because bacteria are at the base of environmental food webs. Our findings illustrate the potential for biomagnification as an ecological impact of nanomaterials.
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, California 93106-9625, USA.
authors.forename: R
authors.initials: R
authors.lastname: Werlin
authors.forename: J H
authors.initials: JH
authors.lastname: Priester
authors.forename: R E
authors.initials: RE
authors.lastname: Mielke
authors.forename: S
authors.initials: S
authors.lastname: Krämer
authors.forename: S
authors.initials: S
authors.lastname: Jackson
authors.forename: P K
authors.initials: PK
authors.lastname: Stoimenov
authors.forename: G D
authors.initials: GD
authors.lastname: Stucky
authors.forename: G N
authors.initials: GN
authors.lastname: Cherr
authors.forename: E
authors.initials: E
authors.lastname: Orias
authors.forename: P A
authors.initials: PA
authors.lastname: Holden
mesh_terms: D019187:Cadmium Compounds / Q000032:analysis*; D020387:Food Chain; D017348:Microscopy, Electron, Scanning Transmission; D049329:Nanostructures / Q000382:microbiology; D011550:Pseudomonas aeruginosa / Q000378:metabolism*; D045663:Quantum Dots; D018036:Selenium Compounds / Q000032:analysis*; D016808:Tetrahymena thermophila / Q000254:growth & development / Q000378:metabolism* / Q000382:microbiology; D014617:Vacuoles
chemical_list: D019187:Cadmium Compounds; D018036:Selenium Compounds; C058667:cadmium selenide